Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding str...Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding strength in titanium/stainless steel laminated composites were investigated.Results indicate that the hardened layer reduces the interfacial bonding strength from over 261 MPa to less than 204 MPa.During the cold roll-bonding process,the hardened layer fractures,leading to the formation of multi-scale cracks that are difficult for the stainless steel to fill.This not only hinders the development of an interlocking interface but also leads to the presence of numerous microcracks and hardened blocks along the nearly straight interface,consequently weakening the interfacial bonding strength.In metals with high work hardening rates,the conventional approach of enhancing interface interlocking and improving interfacial bonding strength by using a surface-hardened layer becomes less effective.展开更多
Continuous casting of high-titanium steels face significant challenges due to steel-flux reactions,which will cause rapid compositional deviations and impair operational stability.A kinetic model to predict real-time ...Continuous casting of high-titanium steels face significant challenges due to steel-flux reactions,which will cause rapid compositional deviations and impair operational stability.A kinetic model to predict real-time mold flux composition evolution by integrating multicomponent mixed-transport-control theory with thermodynamics computing platform was developed in the current study.The model employed a cyclic time-step algorithm to compute thermodynamic equilibrium in reaction layer,mass transfer flux between reaction and bulk layers,and composition updates in reaction and bulk layers.The accuracy of the model was validated by plant trial data.The effect of casting parameters and initial compositions on the evolution of mold flux composition were investigated.The TiO_(2)accumulation and SiO_(2)consumption in mold flux under varying casting parameters was predicted.It was found that higher casting speeds accelerated compositional equilibrium,while the increase of mold flux consumption rates reduced TiO_(2)accumulation.The increase of pool depth resulted in slower consumption and accumulation rates of components like SiO_(2)and TiO_(2),prolonging the time to reach equilibrium.Additionally,the CaO-Al_(2)O_(3)-based flux suppressed the Ti-SiO_(2)reaction for the high-titanium steel continuous casting.However,the CaO-Al_(2)O_(3)-based flux should limited contents of Na_(2)O,MnO,and FeO to prevent additional TiO_(2)accumulation due to Ti-Na_(2)O,Ti-MnO,and Ti-FeO reactions.The model provided a reliable tool for understanding and optimizing the continuous casting process of high-titanium steels.展开更多
Titanium(Ti)/steel clad plates,combining corrosion resistance of titanium with high strength of steel,are critical for applications in petroleum,aerospace,and pressure vessels.This paper comprehensively reviews four m...Titanium(Ti)/steel clad plates,combining corrosion resistance of titanium with high strength of steel,are critical for applications in petroleum,aerospace,and pressure vessels.This paper comprehensively reviews four manufacturing methods:explosive bonding,roll bonding,explosive-roll bonding,and diffusion bonding detailing their advantages,limitations,and mechanisms.Explosive bonding forms a wavy interface with high strength but faces challenges in process control.Roll bonding ensures dimensional precision but suffers from weakened interfaces due to brittle intermetallic compounds(IMCs).Explosive-roll bonding balances efficiency and quality,yet risks IMCs regrowth during reheating.Diffusion bonding minimizes deformation but requires prolonged processing.Analysis of elemental diffusion and compound formation reveals that coexisting TiC and Fe‒Ti IMCs degrade interfacial strength,while interlayers effectively suppress brittle phases.Experimental results highlight that rolling temperatures and interlayer selection critically influence shear strength and tensile properties.The corrugated-flat rolling(CFR)technique enhances mechanical interlocking and diffusion,achieving superior interface bonding strength.Future research should prioritize optimizing process parameters to control IMCs,developing eco-friendly methods,and revealing dynamic interface evolution to research highperformance and large-scale titanium/steel clad plates.展开更多
Titanium exhibits outstanding properties,particularly,high specific strength and resistance to both high and low temperatures,earning it a reputation as the metal of the future.However,because of the highly reactive n...Titanium exhibits outstanding properties,particularly,high specific strength and resistance to both high and low temperatures,earning it a reputation as the metal of the future.However,because of the highly reactive nature of titanium,metallic titanium production involves extensive procedures and high costs.Considering its advantages and limitations,the European Union has classified titanium metal as a critical raw material(CRM)of low category.The Kroll process is predominantly used to produce titanium;however,molten salt electrolysis(MSE)is currently being explored for producing metallic titanium at a low cost.Since 2000,electrolytic titanium production has undergone a wave of technological advancements.However,because of the intermediate and disproportionation reactions in the electrolytic titanium production process,the process efficiency and titanium purity according to industrial standards could not be achieved.Consequently,metallic titanium production has gradually diversified into employing technologies such as thermal reduction,MSE,and titanium alloy preparation.This study provides a comprehensive review of research advances in titanium metal preparation technologies over the past two decades,highlighting the challenges faced by the existing methods and proposing potential solutions.It offers useful insights into the development of low-cost titanium preparation technologies.展开更多
Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely us...Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely used in fields such as injection molding,die casting,and stamping dies.Adding reinforcing particles into steel is an effective means to improve its performance.Nb/18Ni300 composites were fabricated by LPBF using two kinds of Nb powders with different particle sizes,and their microstructures and properties were studied.The results show that the unmelted Nb particles are uniformly distributed in the 18Ni300 matrix and the grains are refined,which is particularly pronounced with fine Nb particles.In addition,element diffusion occurs between the particles and the matrix.The main phases of the base alloy are α-Fe and a small amount of γ-Fe.With the addition of Nb,part of the α-Fe is transformed into γ-Fe,and unmelted Nb phases appear.The addition of Nb also enhances the hardness and wear resistance of the composites but slightly reduces their tensile properties.After aging treatment,the molten pools and grain boundaries become blurred,grains are further refined,and the interfaces around the particles are thinned.The aging treatment also promotes the formation of reverted austenite.The hardness,ultimate tensile strength,and volumetric wear rate of the base alloy reach 51.9 HRC,1704 MPa,and 17.8×10^(-6) mm^(3)/(N·m),respectively.In contrast,the sample added with fine Nb particles has the highest hardness(56.1 HRC),ultimate tensile strength(1892 MPa)and yield strength(1842 MPa),and the volume wear rate of the sample added with coarse Nb particles is reduced by 90%to 1.7×10^(-6) mm^(3)/(N·m).展开更多
Ti-5Al-5Mo-5Cr-2Zr-xNb with different Nb(abbreviated as Ti-5552-xNb,x=3,6,9,12,wt.%)contents were stretched at 923 K to study their superplastic behavior and mechanical properties below recrystallization temperature.T...Ti-5Al-5Mo-5Cr-2Zr-xNb with different Nb(abbreviated as Ti-5552-xNb,x=3,6,9,12,wt.%)contents were stretched at 923 K to study their superplastic behavior and mechanical properties below recrystallization temperature.The microstructure of as-cast Ti-5552-xNb alloy is consisted of a singleβphase,and theβgrain size increases slightly with the increase of Nb content.The thermal effect in the process of high temperature drawing leads to the precipitation ofαphase.The addition of Nb in Ti-5552 titanium alloys reduces theα/βphase transformation temperature,which causes a decrease in the volume fraction ofαphase.Reducing theαphase content reduces incompatibility,but too low a proportion ofαphase will lead to premature fracture,so tensile strength and plasticity firstly increase and then decrease.The results show that Ti-5552-9Nb titanium alloy shows the best tensile strength(307.2 MPa)and superplasticity(106%).The superplastic mechanism of Ti-5552-9Nb alloy is mainly caused by relative sliding ofβgrain boundaries and dislocation movement.展开更多
During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this...During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this paper,the electrochemical dissolution behavior of Ti-6.5Al-2Zr-1Mo-1V(TA15)titanium alloy at without particle impact,low(15°)and high(90°)angle particle impact was investigated,and the influence of Al_(2)O_(3)particles on ECM was systematically expounded.It was found that under the condition of no particle erosion,the surface of electrochemically processed titanium alloy had serious pitting corrosion due to the influence of the passivation film,and the surface roughness(Sa)of the local area reached 10.088μm.Under the condition of a high-impact angle(90°),due to the existence of strain hardening and particle embedding,only the edge of the surface is dissolved,while the central area is almost insoluble,with the surface roughness(S_(a))reaching 16.086μm.On the contrary,under the condition of a low-impact angle(15°),the machining efficiency and surface quality of the material were significantly improved due to the ploughing effect and galvanic corrosion,and the surface roughness(S_(a))reached 2.823μm.Based on these findings,the electrochemical dissolution model of TA15 titanium alloy under different particle erosion conditions was established.展开更多
This study utilizes wet/dry cyclic corrosion testing combined with corrosion big data technology to investigate the mechanism by which chloride ions(Cl^(-))influence the corrosion behavior of 650 MPa high-strength low...This study utilizes wet/dry cyclic corrosion testing combined with corrosion big data technology to investigate the mechanism by which chloride ions(Cl^(-))influence the corrosion behavior of 650 MPa high-strength low-alloy(HSLA)steel in industrially polluted environments.The corrosion process of 650 MPa HSLA steel occurred in two distinct stages:an initial corrosion stage and a stable corrosion stage.During the initial phase,the weight loss rate increased rapidly owing to the instability of the rust layer.Notably,this study demonstrated that 650 MPa HSLA steel exhibited superior corrosion resistance in Cl-containing environments.The formation of a corrosion-product film eventually reduced the weight-loss rate.However,the intrusion of Cl^(-)at increasing concentrations gradually destabilized theα/γ^(*)phases of the rust layer,leading to a looser structure and lower polarization resistance(R_(p)).The application of corrosion big data technology in this study facilitated the validation and analysis of the experimental results,offering new insights into the corrosion mechanisms of HSLA steel in chloride-rich environments.展开更多
The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerge...The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerged entry nozzles,form floaters in the molds,and produce various surface defects on the cast slabs.This review summarizes the effects of nonmetallic inclusions on traditional CaO-SiO_(2)-based(CS)mold fluxes and novel CaO-Al_(2)O_(3)-based(CA)low-or non-reactive fluxes containing TiO_(2),BaO,and B_(2)O_(3)additives to avoid undesirable steel,slag,and inclusion reactions,with the aim of providing a new perspective for research and practice related to balancing the lubrication and heat transfer of mold fluxes to promote smooth operation and reduce surface defects on cast slabs.For traditional CS mold flux,although the addition of solvents such as Na_(2)O,Li_(2)O,and B_(2)O_(3)can enhance flowability,steel-slag reactions persist,limiting the effectiveness of CS mold fluxes in high-Ti steel casting.Low-or non-reactive CA mold fluxes with reduced SiO_(2)content are a research focus,where adding other components can significantly change flux characteristics.Replacing CaO with BaO can lower the melting point and inhibit crystallization,allowing the flux to maintain good flowability at low temperatures.Replacing SiO_(2)with TiO_(2)can stabilize the viscosity and enhance heat transfer.To reduce the environmental impact,fluorides are replaced with components such as TiO_(2),B_(2)O_(3),BaO,Li_(2)O,and Na_(2)O for F-frce mold fluxes with similar lubrication,crystallization,and heat-transfer effects.When TiO_(2)replaces CaF_(2),it stabilizes the viscosity and enhances the heat conductivity,forming CaTiO_(3)and CaSiTiO_(5)phases instead of cuspidine to control crystallization.B_(2)O_(3)lowers the melting point and suppresses crystallization,forming phases such as Ca_(3)B_(2)O_(6)and Ca_(11)Si_(4)B_(2)O_(22).BaO introduces non-bridging oxygen to reduce viscosity and ensure flux flowability at low temperatures.However,further studies are required to determine the optimal mold flux compositions corresponding to the steel grades and the interactions between the various components of the mold flux.In the future,the practical application of new mold fluxes for high-Ti steel will become the focus of further verification to achieve a balance between lubrication and heat transfer,which is expected to minimize the occurrence of casting problems and slab defects.展开更多
The hot-roll bonding was carried out in vacuum between titanium alloy and stainless steel using niobium interlayer. The interfacial structure and mechanical properties were analyzed. The results show that the plastici...The hot-roll bonding was carried out in vacuum between titanium alloy and stainless steel using niobium interlayer. The interfacial structure and mechanical properties were analyzed. The results show that the plasticity of bonded joint is improved significantly. When the bonding temperature is 800 °C or 900 °C, there is not intermetallic layer at the interface between stainless steel and niobium. When the bonding temperature is 1000 °C or 1050 °C, Fe-Nb intermetallic layer forms at the interface. When the bonding temperature is 1050 °C, cracking occurs between stainless steel and intermetallic layer. The maximum strength of -417.5 MPa is obtained at the bonding temperature of 900 °C, the reduction of 25% and the rolling speed of 38 mm/s, and the tensile specimen fractures in the niobium interlayer with plastic fracture characteristics. When the hot-roll bonded transition joints were TIG welded with titanium alloy and stainless steel respectively, the tensile strength of the transition joints after TIG welding is -410.3 MPa, and the specimen fractures in the niobium interlayer.展开更多
Two types of titanium/steel composite plates with the same thickness were manufactured by parallel explosive welding and double vertical explosive welding and rolling, respectively. The comparative analysis of microst...Two types of titanium/steel composite plates with the same thickness were manufactured by parallel explosive welding and double vertical explosive welding and rolling, respectively. The comparative analysis of microstructure showed that the interface of double vertical explosive welding plate （B plate） tended to be straight while the interface of parallel explosive welding plate （A plate） was wavy bonding. Defects near the interface of B plate were extruded, and the thickness of the diffusion layer of B plate was thicker under the effects of preheating temperature and press-working. Comparative tests of mechanical properties indicated that the tensile shear strength of B plate was lower while its micro-hardness was higher. Specimens of these two types of plates were neither separated nor cracked after bending up to 180° in the three-point bending test. From the microstructural observation of tensile fracture characteristics, A plate had strong toughness fracture while B plate had mainly ductile fracture with cleavage fracture as the supplement. Macroscopically, the tensile strength of the latter was 7.9% less than that of the former. However, both satisfied the Chinese standard of tensile strength.展开更多
The effect of intermetallic compounds on the heat resistance of transition joint was investigated. The experiment of post-weld heat treatment for the hot roll bonded titanium alloy-stainless steel joint using nickels ...The effect of intermetallic compounds on the heat resistance of transition joint was investigated. The experiment of post-weld heat treatment for the hot roll bonded titanium alloy-stainless steel joint using nickels interlayer was carried out, and the interface microstructure evolution due to heat treatment was presented. There was not found significant interdiffusion at stainless steel/nickel interface, when the specimens were heat treated in the temperature range of 600-800 °C for 10 and 30 min, while micro-cracks occurred at the stainless steel/nickel interface heat treated at 700 °C for 30 min. The thickness of intermetallic layers at nickel/titanium alloy interface increased at 600 °C, and micro-cracks occurred at 700 and 800 °C. The micro-cracks occurred between intermetallic layers or between intermetallic layer and nickel interlayer as well. The tensile strength of the transition joint decreased with the increase of heat treatment temperature or holding time.展开更多
Ti-Zr-Cu-Ni amorphous filler with good performance is suitable for joining TC and TB titanium alloy, but its melting temperature is higher than 882.5°C, the α→β phase transition temperature of TA2, which makes...Ti-Zr-Cu-Ni amorphous filler with good performance is suitable for joining TC and TB titanium alloy, but its melting temperature is higher than 882.5°C, the α→β phase transition temperature of TA2, which makes the ductility of TA2 fall and the microstructure of the joint coarse. In this paper, Ti-Zr-Cu-Ni amorphous filler was redesigned and optimized by using orthogonal experiment to obtain three easy-to-use Zr-Ti-Ni-Cu amorphous fillers with low melting points and good plasticity. The fast cooling equipment was used to fabricate the brazing filler foils to implement the braze welding of TA2 and Q235 with high frequency inductance. The results indicate that all the brazing foils are amorphous structure with lower melting temperature, for example, Zr52Ti22Ni18Cu8 filler’s is 538°C. The technical parameters in brazing welding are: welding temperature T = 800°C;heating electric current I =25 A;heating time t = 15 s and holding time t = 15 s, in the case of these conditions, the jointing head shear strength of TA2/Zr52Ti24Ni13Cu11/Q235 is 139 MPa. Fracture is mainly located in the brazing seam. The white brittle intermetallic TiFe, TiFe2 and enhancement TiC spread in the center zone of brazing seam.展开更多
Electron beam welding experiments of titanium alloy to stainless steel were carried out with different filler metals, such as Ni, V, and Cu. Microstructures of the joints were examined by optical microscopy, scanning ...Electron beam welding experiments of titanium alloy to stainless steel were carried out with different filler metals, such as Ni, V, and Cu. Microstructures of the joints were examined by optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Mechanical properties of the joints were evaluated according to tensile strength and microhardness. As a result, influences of filler metals on microstructures and mechanical properties of electron beam welded titanium-stainless steel joints were discussed. The results showed that all the filler metals were helpful to restrain the Ti-Fe intermetallics. The welds with different filler metals were all characterized by solid solution and interfacial intermetallics. For each type of the filler metal, the type of solid solution and interfacial intermetallics depended on the metallurgical reactions between the filler metals and base metals. The interfacial intermetallics were Fe2Ti＋Ni3Ti＋NiTi2, TiFe, and Cu2Ti＋CuTi＋CuTi2 in the joints welded with Ni, V, and Cu filler metals, respectively. The tensile strengths of the joints were dependent on the hardness of the interfacial intermetallics. The joint welded with Ag filler metal had the highest tensile strength, which is about 310 MPa.展开更多
Titanium alloy (Ti-Al-V alloy) substrate was brazed with stainless steel (STS304) using filler metal.At an optimized brazing condition,various filler metals were used.Microstructures were observed at each condition.Fi...Titanium alloy (Ti-Al-V alloy) substrate was brazed with stainless steel (STS304) using filler metal.At an optimized brazing condition,various filler metals were used.Microstructures were observed at each condition.Filler metals were titanium based 40Ti-20Zr-20Cu-20Ni,silver based Ag 5Pd,and nickel based Ni-7Cr-3.1B-4.5Si-3Fe-0.06C (BNi2) and Ni-14Cr-10P-0.06C (BNi7).To select a good filler metal for brazing process,wetting test was performed at 880-1050 °C.It was not brazed using silver based filler metals,but at the conditions using titanium and nickel based filler metals had brazed zone between titanium alloy and stainless steel.However,titanium alloy was eroded during brazing using titanium based filler metals.Nickel based filler metal has a good brazed zone between titanium alloy and stainless steel among the filler metals.展开更多
The delayed fracture behaviors of CrMo-type high strength steels containing different amount of titanium(0to 0.10%)were studied.The steels were quenched at 880℃ and tempered from 400℃ to 650℃,and a wide range of te...The delayed fracture behaviors of CrMo-type high strength steels containing different amount of titanium(0to 0.10%)were studied.The steels were quenched at 880℃ and tempered from 400℃ to 650℃,and a wide range of tensile strength was obtained.The sustained load tensile test was carried out by using notched tensile specimens in Walpole solution.The experimental results showed that with higher strength,the Ti-microalloyed steels show higher resistance to delayed fracture compared with non-microalloyed steel due to titanium beneficial role and microstructure changes.The undissolved TiC is uniformly distributed as strong hydrogen traps,retarding or preventing the diffusion and accumulation of hydrogen to lower-interaction energy sites,such as prior austenite and martensite lath boundaries in stress concentration area.Meanwhile,the grain refining effect of titanium is also an important factor to improve the delayed fracture resistance of Ti-microalloyed steels.The characteristics of delayed fracture remain nearly the same with titanium addition.展开更多
In the present study, impulse pressuring diffu- sion bonding technology （IPDB） was utilized between commercially pure titanium and 304 stainless steel （SS） using pure nickel （Ni） as interlayer metal. The interfa...In the present study, impulse pressuring diffu- sion bonding technology （IPDB） was utilized between commercially pure titanium and 304 stainless steel （SS） using pure nickel （Ni） as interlayer metal. The interfacial microstructures of the bonded joints were investigated by scanning electron microscopy （SEM） and energy dispersive spectroscope （EDS） analyses. It is found that with the aid of the Ni interlayer, the interdiffusion and reaction between Ti and SS can be effectively restricted and robust joints can be obtained. Intermetallic compounds （IMCs） including Ti2Ni, TiNi, and TiNi3 are detected at the Ti/Ni interface; however, only Ni-Fe solid solution is found at the Ni/SS interface. The maximum tensile strength of 358 MPa is obtained by IPDB for 90 s and the fracture takes place along the Ti2Ni and TiNi phase upon tensile loading. The existence of cleavage pattern on the fracture surface indi- cates the brittle nature of the joints.展开更多
Hot roll bonding was carried out between commercially pure titanium TA2 and high-strength low-alloy steel Q390 using pure Nb or Mo interlayer at 950 ~C with a total reduction ratio of 86.7%. Interfacial microstructure...Hot roll bonding was carried out between commercially pure titanium TA2 and high-strength low-alloy steel Q390 using pure Nb or Mo interlayer at 950 ~C with a total reduction ratio of 86.7%. Interfacial microstructure and bonding properties of titanium clad steel plates were investigated by electron microscopy and mechanical tests. The results showed β-Ti, TiC and Fe2Ti reaction phases were generated at Ti/steel interface for the clad plates with no interlayer. Inserting Nb or Mo interlayer can effectively suppress the formation of brittle phases, while the weak bonding joint transferred to Nb/steel or Mo/steel interface. And some micro-voids were found at the interface of Nb/steel and Mo/steel. The improved shear strength of clad plates with Nb interlayer might be attributed to the elimination of brittle phases at bonding interface. The small size and little quantities of the micro-voids at Nb/steel interface had a relatively weak effect on shear strength. However, the large number and big size of micro-voids were responsible for the degradation of shear strength for the clad plates with Mo interlayer.展开更多
Electron beam welding experiments of titanium alloys with different vanadium content to stainless steel,as well as alpha titanium to stainless steel using vanadium sheets as filler metal and transition portion were ca...Electron beam welding experiments of titanium alloys with different vanadium content to stainless steel,as well as alpha titanium to stainless steel using vanadium sheets as filler metal and transition portion were carried out.Microstructures of the joints were examined by scanning electron microscope.The properties were evaluated by microhardness and tensile strength.It was shown that electron beam welding is not feasible due to the brittle Ti-Fe intermetallics with high hardness.Increase of vanadium content in base metal can restrain but can't avoid the formation of cracks.When vanadium content was too large,the joint was embrittled by FeTi compound with supersaturated V and also cracked after welding.Crack free joint was achieved by using vanadium transition portion which can prevent the contact of Ti and Fe elements.However,the formation of brittle σ intermetallics reduced the tensile strength of the joint,only up to 134MPa.展开更多
Interface morphology has important influence on the bond quality of titanium clad steel plates. The mechanical properties of titanium clad steel plates with wavy and straight interfaces were investigated by tensile-sh...Interface morphology has important influence on the bond quality of titanium clad steel plates. The mechanical properties of titanium clad steel plates with wavy and straight interfaces were investigated by tensile-shear tests and bending tests. The interface morphology of the plates was examined by optical microscopy （OM） and scanning electron microscopy （SEM）. The experimental results show that the shear strength of a wavy interface is higher than that of a straight interface. A wavy interface is the guarantee for obtaining high shear strength to provide a greater shear resistance. During the maerobending process, cracks appear in the swirl of the wave tip and ferrotitanium intermetallies. For in-situ observing the bending process by SEM, the wave tip of a wavy interface and the massive ferrotitartium intermetallies of a straight interface are places where cracks initiate and propagate. The results are the same as those observed in the macrobending process. Became of high hardness, the wave tip and the massive ferrotitanium intermetallies are hard in terms of compatible deformation.展开更多
基金supported by the National Key R&D Program of China (No. 2018YFA0707300)the National Natural Science Foundation of China (No. 52374376)the Introduction Plan for High end Foreign Experts, China (No. G2023105001L)。
文摘Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding strength in titanium/stainless steel laminated composites were investigated.Results indicate that the hardened layer reduces the interfacial bonding strength from over 261 MPa to less than 204 MPa.During the cold roll-bonding process,the hardened layer fractures,leading to the formation of multi-scale cracks that are difficult for the stainless steel to fill.This not only hinders the development of an interlocking interface but also leads to the presence of numerous microcracks and hardened blocks along the nearly straight interface,consequently weakening the interfacial bonding strength.In metals with high work hardening rates,the conventional approach of enhancing interface interlocking and improving interfacial bonding strength by using a surface-hardened layer becomes less effective.
基金support from the National Key R&D Program(Grant No.2023YFB3709900)the National Natural Science Foundation of China(Grant No.U22A20171)+1 种基金China Baowu Low Carbon Metallurgy Innovation Foundation(Grant No.BWLCF202315)the High Steel Center(HSC)at North China University of Technology and University of Science and Technology Beijing,China.
文摘Continuous casting of high-titanium steels face significant challenges due to steel-flux reactions,which will cause rapid compositional deviations and impair operational stability.A kinetic model to predict real-time mold flux composition evolution by integrating multicomponent mixed-transport-control theory with thermodynamics computing platform was developed in the current study.The model employed a cyclic time-step algorithm to compute thermodynamic equilibrium in reaction layer,mass transfer flux between reaction and bulk layers,and composition updates in reaction and bulk layers.The accuracy of the model was validated by plant trial data.The effect of casting parameters and initial compositions on the evolution of mold flux composition were investigated.The TiO_(2)accumulation and SiO_(2)consumption in mold flux under varying casting parameters was predicted.It was found that higher casting speeds accelerated compositional equilibrium,while the increase of mold flux consumption rates reduced TiO_(2)accumulation.The increase of pool depth resulted in slower consumption and accumulation rates of components like SiO_(2)and TiO_(2),prolonging the time to reach equilibrium.Additionally,the CaO-Al_(2)O_(3)-based flux suppressed the Ti-SiO_(2)reaction for the high-titanium steel continuous casting.However,the CaO-Al_(2)O_(3)-based flux should limited contents of Na_(2)O,MnO,and FeO to prevent additional TiO_(2)accumulation due to Ti-Na_(2)O,Ti-MnO,and Ti-FeO reactions.The model provided a reliable tool for understanding and optimizing the continuous casting process of high-titanium steels.
基金financial supports from the Foundation Strengthening Project(2022-JCJQ-ZD-177-11)the National Natural Science Foundation of China(No.51421001).
文摘Titanium(Ti)/steel clad plates,combining corrosion resistance of titanium with high strength of steel,are critical for applications in petroleum,aerospace,and pressure vessels.This paper comprehensively reviews four manufacturing methods:explosive bonding,roll bonding,explosive-roll bonding,and diffusion bonding detailing their advantages,limitations,and mechanisms.Explosive bonding forms a wavy interface with high strength but faces challenges in process control.Roll bonding ensures dimensional precision but suffers from weakened interfaces due to brittle intermetallic compounds(IMCs).Explosive-roll bonding balances efficiency and quality,yet risks IMCs regrowth during reheating.Diffusion bonding minimizes deformation but requires prolonged processing.Analysis of elemental diffusion and compound formation reveals that coexisting TiC and Fe‒Ti IMCs degrade interfacial strength,while interlayers effectively suppress brittle phases.Experimental results highlight that rolling temperatures and interlayer selection critically influence shear strength and tensile properties.The corrugated-flat rolling(CFR)technique enhances mechanical interlocking and diffusion,achieving superior interface bonding strength.Future research should prioritize optimizing process parameters to control IMCs,developing eco-friendly methods,and revealing dynamic interface evolution to research highperformance and large-scale titanium/steel clad plates.
基金financial support from the Yunnan Province Key Industries Science and Technology Special Project for Colleges and UniversitiesChina(No.FWCY-QYCT2024006)+6 种基金National Natural Science Foundation of China(Nos.52104351 and 52364051)Science and Technology Major Project of Yunnan Province,China(No.202202AG050007)the Yunnan Fundamental Research ProjectsChina(No.202401AT070314)the Key Technology Research and Development Program of Shandong Province,China(No.2023CXGC010903)Central Guidance Local Scientific and Technological Development Funds,China(No.202407AB110022)Yunnan Province Xingdian Talent Support Plan Project,China。
文摘Titanium exhibits outstanding properties,particularly,high specific strength and resistance to both high and low temperatures,earning it a reputation as the metal of the future.However,because of the highly reactive nature of titanium,metallic titanium production involves extensive procedures and high costs.Considering its advantages and limitations,the European Union has classified titanium metal as a critical raw material(CRM)of low category.The Kroll process is predominantly used to produce titanium;however,molten salt electrolysis(MSE)is currently being explored for producing metallic titanium at a low cost.Since 2000,electrolytic titanium production has undergone a wave of technological advancements.However,because of the intermediate and disproportionation reactions in the electrolytic titanium production process,the process efficiency and titanium purity according to industrial standards could not be achieved.Consequently,metallic titanium production has gradually diversified into employing technologies such as thermal reduction,MSE,and titanium alloy preparation.This study provides a comprehensive review of research advances in titanium metal preparation technologies over the past two decades,highlighting the challenges faced by the existing methods and proposing potential solutions.It offers useful insights into the development of low-cost titanium preparation technologies.
基金Key-Area Research and Development Program of Guangdong Province(2023B0909020004)Project of Innovation Research Team in Zhongshan(CXTD2023006)+1 种基金Natural Science Foundation of Guangdong Province(2023A1515011573)Zhongshan Social Welfare Science and Technology Research Project(2024B2022)。
文摘Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely used in fields such as injection molding,die casting,and stamping dies.Adding reinforcing particles into steel is an effective means to improve its performance.Nb/18Ni300 composites were fabricated by LPBF using two kinds of Nb powders with different particle sizes,and their microstructures and properties were studied.The results show that the unmelted Nb particles are uniformly distributed in the 18Ni300 matrix and the grains are refined,which is particularly pronounced with fine Nb particles.In addition,element diffusion occurs between the particles and the matrix.The main phases of the base alloy are α-Fe and a small amount of γ-Fe.With the addition of Nb,part of the α-Fe is transformed into γ-Fe,and unmelted Nb phases appear.The addition of Nb also enhances the hardness and wear resistance of the composites but slightly reduces their tensile properties.After aging treatment,the molten pools and grain boundaries become blurred,grains are further refined,and the interfaces around the particles are thinned.The aging treatment also promotes the formation of reverted austenite.The hardness,ultimate tensile strength,and volumetric wear rate of the base alloy reach 51.9 HRC,1704 MPa,and 17.8×10^(-6) mm^(3)/(N·m),respectively.In contrast,the sample added with fine Nb particles has the highest hardness(56.1 HRC),ultimate tensile strength(1892 MPa)and yield strength(1842 MPa),and the volume wear rate of the sample added with coarse Nb particles is reduced by 90%to 1.7×10^(-6) mm^(3)/(N·m).
基金the financial support by the Major Science and Technology Achievement Transformation Project in Heilongjiang Province(ZC2023SH0075)the National Natural Science Foundation of China(52425401,U2441255,52474377,and 52371015)+1 种基金the Young Elite Scientists Sponsorship Program by·CAST(2021QNRC001)the Henan Provincial Key Research and Development&Promotion Special Program(251111231400)。
文摘Ti-5Al-5Mo-5Cr-2Zr-xNb with different Nb(abbreviated as Ti-5552-xNb,x=3,6,9,12,wt.%)contents were stretched at 923 K to study their superplastic behavior and mechanical properties below recrystallization temperature.The microstructure of as-cast Ti-5552-xNb alloy is consisted of a singleβphase,and theβgrain size increases slightly with the increase of Nb content.The thermal effect in the process of high temperature drawing leads to the precipitation ofαphase.The addition of Nb in Ti-5552 titanium alloys reduces theα/βphase transformation temperature,which causes a decrease in the volume fraction ofαphase.Reducing theαphase content reduces incompatibility,but too low a proportion ofαphase will lead to premature fracture,so tensile strength and plasticity firstly increase and then decrease.The results show that Ti-5552-9Nb titanium alloy shows the best tensile strength(307.2 MPa)and superplasticity(106%).The superplastic mechanism of Ti-5552-9Nb alloy is mainly caused by relative sliding ofβgrain boundaries and dislocation movement.
基金supported by the National Natural Science Foundation of China(No.52175414)the Natural Science Foundation of Jiangsu Province of China(No.BK20220134)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.NE2023002)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(No.KYCX24_0559)。
文摘During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this paper,the electrochemical dissolution behavior of Ti-6.5Al-2Zr-1Mo-1V(TA15)titanium alloy at without particle impact,low(15°)and high(90°)angle particle impact was investigated,and the influence of Al_(2)O_(3)particles on ECM was systematically expounded.It was found that under the condition of no particle erosion,the surface of electrochemically processed titanium alloy had serious pitting corrosion due to the influence of the passivation film,and the surface roughness(Sa)of the local area reached 10.088μm.Under the condition of a high-impact angle(90°),due to the existence of strain hardening and particle embedding,only the edge of the surface is dissolved,while the central area is almost insoluble,with the surface roughness(S_(a))reaching 16.086μm.On the contrary,under the condition of a low-impact angle(15°),the machining efficiency and surface quality of the material were significantly improved due to the ploughing effect and galvanic corrosion,and the surface roughness(S_(a))reached 2.823μm.Based on these findings,the electrochemical dissolution model of TA15 titanium alloy under different particle erosion conditions was established.
基金financially supported by the National Natural Science Foundation of China(Nos.52104319 and 52374323)。
文摘This study utilizes wet/dry cyclic corrosion testing combined with corrosion big data technology to investigate the mechanism by which chloride ions(Cl^(-))influence the corrosion behavior of 650 MPa high-strength low-alloy(HSLA)steel in industrially polluted environments.The corrosion process of 650 MPa HSLA steel occurred in two distinct stages:an initial corrosion stage and a stable corrosion stage.During the initial phase,the weight loss rate increased rapidly owing to the instability of the rust layer.Notably,this study demonstrated that 650 MPa HSLA steel exhibited superior corrosion resistance in Cl-containing environments.The formation of a corrosion-product film eventually reduced the weight-loss rate.However,the intrusion of Cl^(-)at increasing concentrations gradually destabilized theα/γ^(*)phases of the rust layer,leading to a looser structure and lower polarization resistance(R_(p)).The application of corrosion big data technology in this study facilitated the validation and analysis of the experimental results,offering new insights into the corrosion mechanisms of HSLA steel in chloride-rich environments.
基金financially supported by the National Natural Science Foundation of China(Nos.52204345 and 52474361)the Scientific Research Innovation Projects of Graduate Student of Jiangsu province,China(No.KYCX24_4184)。
文摘The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerged entry nozzles,form floaters in the molds,and produce various surface defects on the cast slabs.This review summarizes the effects of nonmetallic inclusions on traditional CaO-SiO_(2)-based(CS)mold fluxes and novel CaO-Al_(2)O_(3)-based(CA)low-or non-reactive fluxes containing TiO_(2),BaO,and B_(2)O_(3)additives to avoid undesirable steel,slag,and inclusion reactions,with the aim of providing a new perspective for research and practice related to balancing the lubrication and heat transfer of mold fluxes to promote smooth operation and reduce surface defects on cast slabs.For traditional CS mold flux,although the addition of solvents such as Na_(2)O,Li_(2)O,and B_(2)O_(3)can enhance flowability,steel-slag reactions persist,limiting the effectiveness of CS mold fluxes in high-Ti steel casting.Low-or non-reactive CA mold fluxes with reduced SiO_(2)content are a research focus,where adding other components can significantly change flux characteristics.Replacing CaO with BaO can lower the melting point and inhibit crystallization,allowing the flux to maintain good flowability at low temperatures.Replacing SiO_(2)with TiO_(2)can stabilize the viscosity and enhance heat transfer.To reduce the environmental impact,fluorides are replaced with components such as TiO_(2),B_(2)O_(3),BaO,Li_(2)O,and Na_(2)O for F-frce mold fluxes with similar lubrication,crystallization,and heat-transfer effects.When TiO_(2)replaces CaF_(2),it stabilizes the viscosity and enhances the heat conductivity,forming CaTiO_(3)and CaSiTiO_(5)phases instead of cuspidine to control crystallization.B_(2)O_(3)lowers the melting point and suppresses crystallization,forming phases such as Ca_(3)B_(2)O_(6)and Ca_(11)Si_(4)B_(2)O_(22).BaO introduces non-bridging oxygen to reduce viscosity and ensure flux flowability at low temperatures.However,further studies are required to determine the optimal mold flux compositions corresponding to the steel grades and the interactions between the various components of the mold flux.In the future,the practical application of new mold fluxes for high-Ti steel will become the focus of further verification to achieve a balance between lubrication and heat transfer,which is expected to minimize the occurrence of casting problems and slab defects.
基金Project(AWPT-M07)supported by State Key Laboratory of Advanced Welding and Joining,ChinaProject(20120041120015)supported by Specialized Research Fund for the Doctoral Program of Higher Education,China
文摘The hot-roll bonding was carried out in vacuum between titanium alloy and stainless steel using niobium interlayer. The interfacial structure and mechanical properties were analyzed. The results show that the plasticity of bonded joint is improved significantly. When the bonding temperature is 800 °C or 900 °C, there is not intermetallic layer at the interface between stainless steel and niobium. When the bonding temperature is 1000 °C or 1050 °C, Fe-Nb intermetallic layer forms at the interface. When the bonding temperature is 1050 °C, cracking occurs between stainless steel and intermetallic layer. The maximum strength of -417.5 MPa is obtained at the bonding temperature of 900 °C, the reduction of 25% and the rolling speed of 38 mm/s, and the tensile specimen fractures in the niobium interlayer with plastic fracture characteristics. When the hot-roll bonded transition joints were TIG welded with titanium alloy and stainless steel respectively, the tensile strength of the transition joints after TIG welding is -410.3 MPa, and the specimen fractures in the niobium interlayer.
基金This project was sponsored by the National Natural Science Foundation of China （No. 51541112） and Special Fund Achievement Transformation Projects in Jiangsu of China （No. BA2012030）.
文摘Two types of titanium/steel composite plates with the same thickness were manufactured by parallel explosive welding and double vertical explosive welding and rolling, respectively. The comparative analysis of microstructure showed that the interface of double vertical explosive welding plate （B plate） tended to be straight while the interface of parallel explosive welding plate （A plate） was wavy bonding. Defects near the interface of B plate were extruded, and the thickness of the diffusion layer of B plate was thicker under the effects of preheating temperature and press-working. Comparative tests of mechanical properties indicated that the tensile shear strength of B plate was lower while its micro-hardness was higher. Specimens of these two types of plates were neither separated nor cracked after bending up to 180° in the three-point bending test. From the microstructural observation of tensile fracture characteristics, A plate had strong toughness fracture while B plate had mainly ductile fracture with cleavage fracture as the supplement. Macroscopically, the tensile strength of the latter was 7.9% less than that of the former. However, both satisfied the Chinese standard of tensile strength.
基金Project(AWPT-M07)supported by the State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology
文摘The effect of intermetallic compounds on the heat resistance of transition joint was investigated. The experiment of post-weld heat treatment for the hot roll bonded titanium alloy-stainless steel joint using nickels interlayer was carried out, and the interface microstructure evolution due to heat treatment was presented. There was not found significant interdiffusion at stainless steel/nickel interface, when the specimens were heat treated in the temperature range of 600-800 °C for 10 and 30 min, while micro-cracks occurred at the stainless steel/nickel interface heat treated at 700 °C for 30 min. The thickness of intermetallic layers at nickel/titanium alloy interface increased at 600 °C, and micro-cracks occurred at 700 and 800 °C. The micro-cracks occurred between intermetallic layers or between intermetallic layer and nickel interlayer as well. The tensile strength of the transition joint decreased with the increase of heat treatment temperature or holding time.
文摘Ti-Zr-Cu-Ni amorphous filler with good performance is suitable for joining TC and TB titanium alloy, but its melting temperature is higher than 882.5°C, the α→β phase transition temperature of TA2, which makes the ductility of TA2 fall and the microstructure of the joint coarse. In this paper, Ti-Zr-Cu-Ni amorphous filler was redesigned and optimized by using orthogonal experiment to obtain three easy-to-use Zr-Ti-Ni-Cu amorphous fillers with low melting points and good plasticity. The fast cooling equipment was used to fabricate the brazing filler foils to implement the braze welding of TA2 and Q235 with high frequency inductance. The results indicate that all the brazing foils are amorphous structure with lower melting temperature, for example, Zr52Ti22Ni18Cu8 filler’s is 538°C. The technical parameters in brazing welding are: welding temperature T = 800°C;heating electric current I =25 A;heating time t = 15 s and holding time t = 15 s, in the case of these conditions, the jointing head shear strength of TA2/Zr52Ti24Ni13Cu11/Q235 is 139 MPa. Fracture is mainly located in the brazing seam. The white brittle intermetallic TiFe, TiFe2 and enhancement TiC spread in the center zone of brazing seam.
基金Project(2011DFR50760)supported by International Science&Technology Cooperation Program of China
文摘Electron beam welding experiments of titanium alloy to stainless steel were carried out with different filler metals, such as Ni, V, and Cu. Microstructures of the joints were examined by optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Mechanical properties of the joints were evaluated according to tensile strength and microhardness. As a result, influences of filler metals on microstructures and mechanical properties of electron beam welded titanium-stainless steel joints were discussed. The results showed that all the filler metals were helpful to restrain the Ti-Fe intermetallics. The welds with different filler metals were all characterized by solid solution and interfacial intermetallics. For each type of the filler metal, the type of solid solution and interfacial intermetallics depended on the metallurgical reactions between the filler metals and base metals. The interfacial intermetallics were Fe2Ti＋Ni3Ti＋NiTi2, TiFe, and Cu2Ti＋CuTi＋CuTi2 in the joints welded with Ni, V, and Cu filler metals, respectively. The tensile strengths of the joints were dependent on the hardness of the interfacial intermetallics. The joint welded with Ag filler metal had the highest tensile strength, which is about 310 MPa.
文摘Titanium alloy (Ti-Al-V alloy) substrate was brazed with stainless steel (STS304) using filler metal.At an optimized brazing condition,various filler metals were used.Microstructures were observed at each condition.Filler metals were titanium based 40Ti-20Zr-20Cu-20Ni,silver based Ag 5Pd,and nickel based Ni-7Cr-3.1B-4.5Si-3Fe-0.06C (BNi2) and Ni-14Cr-10P-0.06C (BNi7).To select a good filler metal for brazing process,wetting test was performed at 880-1050 °C.It was not brazed using silver based filler metals,but at the conditions using titanium and nickel based filler metals had brazed zone between titanium alloy and stainless steel.However,titanium alloy was eroded during brazing using titanium based filler metals.Nickel based filler metal has a good brazed zone between titanium alloy and stainless steel among the filler metals.
基金Item Sponsored by National Key Fundamental Research and Development Project of China(G1998061503)National Science and Technology Development Project of China(2002BA314B08)
文摘The delayed fracture behaviors of CrMo-type high strength steels containing different amount of titanium(0to 0.10%)were studied.The steels were quenched at 880℃ and tempered from 400℃ to 650℃,and a wide range of tensile strength was obtained.The sustained load tensile test was carried out by using notched tensile specimens in Walpole solution.The experimental results showed that with higher strength,the Ti-microalloyed steels show higher resistance to delayed fracture compared with non-microalloyed steel due to titanium beneficial role and microstructure changes.The undissolved TiC is uniformly distributed as strong hydrogen traps,retarding or preventing the diffusion and accumulation of hydrogen to lower-interaction energy sites,such as prior austenite and martensite lath boundaries in stress concentration area.Meanwhile,the grain refining effect of titanium is also an important factor to improve the delayed fracture resistance of Ti-microalloyed steels.The characteristics of delayed fracture remain nearly the same with titanium addition.
基金financially supported by the National Natural Science Foundation of China(No.50675234)
文摘In the present study, impulse pressuring diffu- sion bonding technology （IPDB） was utilized between commercially pure titanium and 304 stainless steel （SS） using pure nickel （Ni） as interlayer metal. The interfacial microstructures of the bonded joints were investigated by scanning electron microscopy （SEM） and energy dispersive spectroscope （EDS） analyses. It is found that with the aid of the Ni interlayer, the interdiffusion and reaction between Ti and SS can be effectively restricted and robust joints can be obtained. Intermetallic compounds （IMCs） including Ti2Ni, TiNi, and TiNi3 are detected at the Ti/Ni interface; however, only Ni-Fe solid solution is found at the Ni/SS interface. The maximum tensile strength of 358 MPa is obtained by IPDB for 90 s and the fracture takes place along the Ti2Ni and TiNi phase upon tensile loading. The existence of cleavage pattern on the fracture surface indi- cates the brittle nature of the joints.
文摘Hot roll bonding was carried out between commercially pure titanium TA2 and high-strength low-alloy steel Q390 using pure Nb or Mo interlayer at 950 ~C with a total reduction ratio of 86.7%. Interfacial microstructure and bonding properties of titanium clad steel plates were investigated by electron microscopy and mechanical tests. The results showed β-Ti, TiC and Fe2Ti reaction phases were generated at Ti/steel interface for the clad plates with no interlayer. Inserting Nb or Mo interlayer can effectively suppress the formation of brittle phases, while the weak bonding joint transferred to Nb/steel or Mo/steel interface. And some micro-voids were found at the interface of Nb/steel and Mo/steel. The improved shear strength of clad plates with Nb interlayer might be attributed to the elimination of brittle phases at bonding interface. The small size and little quantities of the micro-voids at Nb/steel interface had a relatively weak effect on shear strength. However, the large number and big size of micro-voids were responsible for the degradation of shear strength for the clad plates with Mo interlayer.
文摘Electron beam welding experiments of titanium alloys with different vanadium content to stainless steel,as well as alpha titanium to stainless steel using vanadium sheets as filler metal and transition portion were carried out.Microstructures of the joints were examined by scanning electron microscope.The properties were evaluated by microhardness and tensile strength.It was shown that electron beam welding is not feasible due to the brittle Ti-Fe intermetallics with high hardness.Increase of vanadium content in base metal can restrain but can't avoid the formation of cracks.When vanadium content was too large,the joint was embrittled by FeTi compound with supersaturated V and also cracked after welding.Crack free joint was achieved by using vanadium transition portion which can prevent the contact of Ti and Fe elements.However,the formation of brittle σ intermetallics reduced the tensile strength of the joint,only up to 134MPa.
文摘Interface morphology has important influence on the bond quality of titanium clad steel plates. The mechanical properties of titanium clad steel plates with wavy and straight interfaces were investigated by tensile-shear tests and bending tests. The interface morphology of the plates was examined by optical microscopy （OM） and scanning electron microscopy （SEM）. The experimental results show that the shear strength of a wavy interface is higher than that of a straight interface. A wavy interface is the guarantee for obtaining high shear strength to provide a greater shear resistance. During the maerobending process, cracks appear in the swirl of the wave tip and ferrotitanium intermetallies. For in-situ observing the bending process by SEM, the wave tip of a wavy interface and the massive ferrotitartium intermetallies of a straight interface are places where cracks initiate and propagate. The results are the same as those observed in the macrobending process. Became of high hardness, the wave tip and the massive ferrotitanium intermetallies are hard in terms of compatible deformation.
