A robot flexible processing system of shipbuilding profile steel was developed. The system consists of computer integrated control and robot. An off line programming robot was used for marking and cutting of shipbuil...A robot flexible processing system of shipbuilding profile steel was developed. The system consists of computer integrated control and robot. An off line programming robot was used for marking and cutting of shipbuilding profile steel. In the system the deformation and position error of profile steel can be detected by precise sensors, and figure position coordinate error resulted from profile steel deformation can be compensated by modifying traveling track of robotic arm online. The practical operation results show that the system performance can meet the needs of profile steel processing.展开更多
Hot deformation behavior of as-cast Mn18Cr18 N austenitic stainless steel was studied in the temperature range of 950-1200 ℃ and strain rate range of 0.001-1 s^（-1） using isothermal hot compression tests. The true ...Hot deformation behavior of as-cast Mn18Cr18 N austenitic stainless steel was studied in the temperature range of 950-1200 ℃ and strain rate range of 0.001-1 s^（-1） using isothermal hot compression tests. The true stress-strain curves of the steel were characterized by hardening and subsequent softening and varied with temperatures and strain rates. The hot deformation activation energy of the steel was calculated to be 657.4 k J/mol, which was higher than that of the corresponding wrought steel due to its as-cast coarse columnar grains and heterogeneous structure. Hot processing maps were developed at different plastic strains, which exhibited two domains with peak power dissipation efficiencies at 1150 ℃/0.001 s^（-1） and 1200 ℃/1 s^（-1）, respectively. The corresponding microstructures were analyzed by optical microscopy（OM）, scanning electron microscopy（SEM）, and electron backscatter diffraction（EBSD）. It has been confirmed that dynamic recrystallization（DRX） controlled by dislocation slipping and climbing mechanism occurs in the temperature and strain rate range of 1050-1200 ℃ and 0.001-0.01 s^（-1）; And DRX controlled by twinning mechanism occurs in the temperature and strain rate range of 1100-1200 ℃, 0.1-1 s^（-1）. These two DRX domains can serve as the hot working windows of the as-cast steel at lower strain rates and at higher strain rates, respectively. The processing maps at different strains also exhibit that the instability region decreases with increasing strain. The corresponding microstructures and the less tensile ductility in the instability region imply that the flow instability is attributed to flow localization accelerated by a few layers of very fine recrystallized grains along the original grain boundaries.展开更多
Friction stir processing （FSP） was investigated as a method of repairing cracks in 12 mm thick 304L stainless steel plate. Healing feasibility was demonstrated by processing a tapered crack using a PCBN/W- Re tool w...Friction stir processing （FSP） was investigated as a method of repairing cracks in 12 mm thick 304L stainless steel plate. Healing feasibility was demonstrated by processing a tapered crack using a PCBN/W- Re tool with a 25 mm diameter shoulder and a pin length of 6.4 mm. The experiment showed that it was possible to heal a crack that begins narrow and then progressively grows up to a width of 2 mm. Bead on plate experiments were used to find the best parameters for creating a consolidated stir zone with the least amount of hardness difference compared to the base metal. Grain refinement in some specimens resulted in much higher stir zone hardness, compared to base metal, A plot of grain size versus microhardness showed a very strong inverse correlation between grain size and hardness, as expected from the Hall- Perch relationship. Corrosion testing was carried out in order to evaluate the effect of FSP on potential sensitization of the stir zone. After 1000 h of intermittent immersion in 3.5% saline solution at room temperature it was found that no corrosion products formed on the base material controls or on any of the friction stir processed specimens.展开更多
Hot deformation behavior of a new type of M3∶ 2 high speed steel with niobium addition made by spray forming was investigated based on compression tests in the temperature range of 950-1 150 ℃ and strain rate of 0. ...Hot deformation behavior of a new type of M3∶ 2 high speed steel with niobium addition made by spray forming was investigated based on compression tests in the temperature range of 950-1 150 ℃ and strain rate of 0. 001-10 s^（-1）. A comprehensive constitutive equation was obtained,which could be used to predict the flow stress at different strains. Processing map was developed on the basis of the flow stress data using the principles of dynamic material model. The results showed that the flow curves were in fair agreement with the dynamic recrystallization model. The flow stresses,which were calculated by the comprehensive constitutive equation,agreed well with the test data at low strain rates（ ≤1 s^（-1））. The material constant（ α）,stress exponent（ n） and the hot deformation activation energy（ Q_（HW）） of the new steel were 0. 006 15 MPa^（-1）,4. 81 and 546 kJ·mol^（-1）,respectively. Analysis of the processing map with an observation of microstructures revealed that hot working processes of the steel could be carried out safely in the domain（ T = 1 050-1 150 ℃,ε = 0. 01- 0. 1 s^（-1））with about 33% peak efficiency of power dissipation（ η）. Cracks was expected in two domains at either lower temperatures（ 〈 1 000 ℃） or low strain rates（ 0. 001 s^（-1）） with different cracking mechanisms. Flow localization occurred when the strain rates exceeded 1 s^（-1） at all testing temperatures.展开更多
In this paper, we use femtosecond laser pulse to scribe 304 stainless steel foil, detect the Fourier transform infrared spectrum of the sample before and after processing, confirm the "cold processing" and &...In this paper, we use femtosecond laser pulse to scribe 304 stainless steel foil, detect the Fourier transform infrared spectrum of the sample before and after processing, confirm the "cold processing" and "thermal processing" and their mutual conversion, and determine the "cold processing" parameter window. The ablation threshold and incubation coefficient of 304 stainless steel foil are calculated, and the effects of scanning speed and effective pulse number on the ablation threshold are analyzed. The ANSYS software is used to simulate the radial and axial temperature distributions of the surface on 304 stainless steel foil sample and the heat-affected zone with a femtosecond laser fluence of 10 J/cm2 and an effective number of pulses of 1 200 are obtained. In the aspect of spectral detection, the Fourier transform infrared spectra of the sample before and after processing are measured and two processing mechanisms of "cold processing" and "hot processing" are confirmed, which proves that we can achieve the conversion between "cold processing" and "hot processing" by changing the laser fluence and determine the "cold processing" laser fluence range.展开更多
The steel belt roasting process has the advantages of low cost,small footprint,and high thermal efficiency,making it widely used in the smelting of ferroalloys such as ferrochrome,ferromanganese,and ferroniobium.Howev...The steel belt roasting process has the advantages of low cost,small footprint,and high thermal efficiency,making it widely used in the smelting of ferroalloys such as ferrochrome,ferromanganese,and ferroniobium.However,its application in preparing iron ore oxidized pellets has not been sufficiently explored.The optimal thermal process conditions for magnesium-containing oxidized pellet preparation by steel belt roasting machine were investigated based on the roasting properties of high-magnesium iron concentrate and typical iron concentrate.The results indicate that,for the blending scheme of 70 wt.%high-magnesium iron concentrate and 30 wt.%typical iron concentrate,the appropriate preheating temperature for pellets is 950–975℃and the suitable roasting temperature is 1250–1275℃,during which the compressive strength of pellets can exceed 2500 N pellet−1.During the steel belt roasting process,SO_(2)is primarily released in the preheating zone,and the maximum exhaust gas temperature in the roasting zone can reach 637℃.High-temperature sulfur-containing exhaust gas causes oxidation corrosion,sulfide corrosion,and deformation of the steel belt.To enhance the steel belt longevity,it is recommended to appropriately reduce the wind velocity in the preheating zone and roasting zone,while also decreasing the ratio of pellet bed height to hearth layer height.By adopting the system of“low wind velocity,thin pellet bed,fast steel belt speed,”the exhaust gas temperature can be reduced to 463℃.The prepared pellet maintains a compressive strength of 2607 N pellet^(-1)and exhibits excellent metallurgical properties.展开更多
During this research, experimental rolled homogeneous armour steel was cast, annealed and laser cut to form an appliqué plate. This Martensitic–Bainitic microstructure steel grade was used to test a novel means ...During this research, experimental rolled homogeneous armour steel was cast, annealed and laser cut to form an appliqué plate. This Martensitic–Bainitic microstructure steel grade was used to test a novel means of engineering lightweight armour. It was determined that a laser cutting speed of 1200 mm/min produced optimum hole formations with limited distortion. The array of holes acts as a double-edged solution, in that they provide weight saving of 45%, providing a protective advantage and increasing the surface area. Data collected were used to generate laser cut-edge hole projections in order to identify the optimum cutting speed, edge condition, cost and deformation performance. These parameters resulted in the generation of a surface, with less stress raising features. This can result in a distribution of stress across the wider surface. Provided that appropriate process parameters are used to generate laser cut edges, then the hardness properties of the surface can be controlled. This is due to compressive residual stresses produced in the near edge region as a result of metallurgical transformations. This way the traverse cutting speed parameter can be adjusted to alter critical surface characteristics and microstructural properties in close proximity to the cut-edge. A relationship was identified between the width of the laser HAZ and the hardness of the cut edge. It is the thickness of the HAZ that is affected by the laser process parameters which can be manipulated with adjusting the traverse cutting speed.展开更多
The half-inverted "T" type invisible cover beam is a new type of cover beam with simple and beautiful appearance, but complicated structure. In this paper, the steel bar of the semi-inverted T-shaped invisib...The half-inverted "T" type invisible cover beam is a new type of cover beam with simple and beautiful appearance, but complicated structure. In this paper, the steel bar of the semi-inverted T-shaped invisible cover beam is taken as the research object, and the whole process from data output to optimal design and then to standard processing is studied. By using BIM technology and intelligent steel bending machine, solutions are proposed for the production of complex steel bars.展开更多
In order to promote the intelligent transformation and upgrading of the steel industry, intelligent technology features based on the current situation and challenges of the steel industry are discussed in this paper. ...In order to promote the intelligent transformation and upgrading of the steel industry, intelligent technology features based on the current situation and challenges of the steel industry are discussed in this paper. Based on both domestic and global research, functional analysis, reasonable positioning, and process optimization of each aspect of steel making are expounded. The current state of molten steel quality and implementation under narrow window control is analyzed. A method for maintaining stability in the narrow window control technology of steel quality is proposed, controlled by factors including composition, temperature, time, cleanliness, and consumption(raw material). Important guidance is provided for the future development of a green and intelligent steel manufacturing process.展开更多
Against the realistic background of excess production capacity, product structure imbalance, and high material and energy consumption in steel enterprises, the implementation of operation optimization for the steel ma...Against the realistic background of excess production capacity, product structure imbalance, and high material and energy consumption in steel enterprises, the implementation of operation optimization for the steel manufacturing process is essential to reduce the production cost, increase the production or energy efficiency, and improve production management. In this study, the operation optimization problem of the steel manufacturing process, which needed to go through a complex production organization from customers' orders to workshop production, was analyzed. The existing research on the operation optimization techniques, including process simulation, production planning, production scheduling, interface scheduling, and scheduling of auxiliary equipment, was reviewed. The literature review reveals that, although considerable research has been conducted to optimize the operation of steel production, these techniques are usually independent and unsystematic.Therefore, the future work related to operation optimization of the steel manufacturing process based on the integration of multi technologies and the intersection of multi disciplines were summarized.展开更多
From the viewpoint of systems energy conservation, the influences of material flow on its energy consumption in a steel manufacturing process is an important subject. The quantitative analysis of the relationship betw...From the viewpoint of systems energy conservation, the influences of material flow on its energy consumption in a steel manufacturing process is an important subject. The quantitative analysis of the relationship between material flow and the energy intensity is useful to save energy in steel industry. Based on the concept of standard material flow diagram, all possible situations of ferric material flow in steel manufacturing process are analyzed. The expressions of the influence of material flow deviated from standard material flow diagram on energy consumption are put forward.展开更多
Theoretical minimum and actual specific energy consumptions （SEC） of typical manufacturing process （SMP） were studied. Firstly, a process division of a typical SMP in question was conducted with the theory of SEC ...Theoretical minimum and actual specific energy consumptions （SEC） of typical manufacturing process （SMP） were studied. Firstly, a process division of a typical SMP in question was conducted with the theory of SEC analysis. Secondly, an exergy analysis model of a subsystem consisting of several parallel processes and a SEC analysis model of SMP were developed. And finally, based on the analysis models, the SEC of SMP was analyzed by means of the statistical significance. The results show that the SEC of typical SMP comprises the theoretical minimum SEC and the additional SEC derived from the irreversibility~ and the SMP has a theoretical minimum SEC of 6.74 GJ/t and an additional SEC of 19.32 GJ/t, which account for 25.88% and 74.12% of the actual SEC, respectively.展开更多
The standard material flow diagram in steel manufacturing process was proposed to analyze the influences of various material flows on environmental load of 1tof final product.Two influence factors and reducing measure...The standard material flow diagram in steel manufacturing process was proposed to analyze the influences of various material flows on environmental load of 1tof final product.Two influence factors and reducing measures of environmental load were pointed out.The environmental load was appraised for a typical technological process in a Chinese steel plant.展开更多
Texture inhomogeneity usually takes place in ferritic stainless steels due to the lack of phase transformation and recrystallization during hot strip rolling,which can deteriorate the formability of final sheets.In or...Texture inhomogeneity usually takes place in ferritic stainless steels due to the lack of phase transformation and recrystallization during hot strip rolling,which can deteriorate the formability of final sheets.In order to work out the way of weakening texture inhomogeneity,conventional hot rolling and warm rolling processes have been carried out with an ultra purified ferritic stainless steel.The results showed that the evolution of through-thickness texture is closely dependent on rolling process,especially for the texture in the center layer.For both conventional and warm rolling processes,shear texture components were formed in the surface layers after hot rolling and annealing;sharp α-fiber and weakγ-fiber with the major component at{111}〈110〉 were developed in both cold rolled sheet surfaces,leading to the formation of inhomogeneousγ-fiber dominated by{111}〈112〉after recrystallization annealing.In the center layer of conventional rolled and annealed bands,strongα-fiber and weakγ-fiber textures were formed;the cold rolled textures were comprised of sharpα-fiber and weakγ-fiber with the major component at{111}〈110〉,and inhomogeneousγ-fiber dominated by{111}〈112〉 was formed after recrystallization annealing.By contrast,in the centre layer of warm rolled bands,the texture was comprised of weakα-fiber and sharpγ-fiber,andγ-fiber became the only component after annealing.The cold rolled texture displayed a sharpγ-fiber with the major component at{111}〈112〉and the intensity ofγ-fiber close to that ofα-fiber,resulting in the formation of a nearly homogeneousγ-fiber recrystallization texture in the center layer of the final sheet.展开更多
The striations on the surface of 3Cr2W8V die steel were processed by laser. The microstructure, hardness, wear resistance and thermal fatigue behavior of the specimens processed by laser were measured. The appearance ...The striations on the surface of 3Cr2W8V die steel were processed by laser. The microstructure, hardness, wear resistance and thermal fatigue behavior of the specimens processed by laser were measured. The appearance and mechanism of thermal fatigue crack propagation in the zone processed by laser were observed and discussed. The results show that the wear resistance and thermal fatigue resistance of materials processed by laser are all better than those of the unprocessed material. The processed zone by laser plays a role in baffling wearing process and crack propagation. The pile-nail effect of processed zone is the main factor for improving the wear resistance and thermal fatigue resistance of material.展开更多
A production planning system is designed for the whole steelmaking process, which includes desulfurization, vanadium extraction, steelmaking and continuous casting processes of Panzhihua Iron and Steel Corporation. Th...A production planning system is designed for the whole steelmaking process, which includes desulfurization, vanadium extraction, steelmaking and continuous casting processes of Panzhihua Iron and Steel Corporation. The system is composed of modeling module, data interface module, data analysis module, static planning module, re-planning module, plan evaluation module, plan simulation module and human-computer interaction module. The system is connected with the L3 system of steel plant by using the data interface module, which can receive the real time scheduling information to make the static plan and re-plan under production disturbances. The simulation and plan evaluation function of the system can assist decision-maker to check and modify the production plan. The simulation experiments with real process data show that the system can make a feasible, executable, and effective production plan, and deal with primary random disturbances during production process timely.展开更多
A siliconizing process to manufacture 6.5% Si steel sheet has been developed. Electric components, such as transformers and reactors are made easily from 6.5% Si steel sheet. However, improved workability is desirable...A siliconizing process to manufacture 6.5% Si steel sheet has been developed. Electric components, such as transformers and reactors are made easily from 6.5% Si steel sheet. However, improved workability is desirable to increase the applications. Therefore the improvement of workability of 6.5% Si steel sheet was investigated, and the results were obtained as follows: (a) workability of 6.5% Si steel sheet is deteriorated by grain boundary oxidization, (b) grain boundary oxidization can be restrained by the addition of C. Workability and magnetic properties of 6.5% Si steel sheet with C addition are discussed. Furthermore, it was found that the workability of high Si steel sheet was improved remarkably by varying the Si content gradient along the thickness without deterioration of high frequency magnetic properties. This newly developed magnetic gradient high Si steel sheet is also discussed.展开更多
The stretch formability of a low carbon steel processed by friction stir processing （FSP） was studied under biaxial loading condition applied by a miniaturized Erichsen test. One-pass FSP decreased the ferritic grai...The stretch formability of a low carbon steel processed by friction stir processing （FSP） was studied under biaxial loading condition applied by a miniaturized Erichsen test. One-pass FSP decreased the ferritic grain size in the processed zone from 25 μm to about 3 μm, which also caused a remarkable increase in strength values without considerable decrease in formability under uniaxial loading. A coarse-grained （CG） sample before FSP reflected a moderate formability with an Erichsen index （EI） of 2.73 mm. FSP slightly decreased the stretch formability of the sample to 2.66 ram. However, FSP increased the required punch load （FEI） due to the increased strength by grain refinement. FSP reduced considerably the roughness of the free surface of the biaxial stretched samples with reduced orange peel effect. The average roughness value （Ra） decreased from 2.90 in the CG sample down to about 0.65 μm in fine-grained （FG） sample after FSP. It can be concluded that the FG microstructure in low carbon steels sheets or plates used generally in shipbuilding provides a good balance between strength and formability.展开更多
A new kind of corrosion resistant steelfor cargo oiltanks（COT）was developed.The influences of finalrolling temperature,cooling rate,and finalcooling temperature on microstructure were investigated.The proper rolling...A new kind of corrosion resistant steelfor cargo oiltanks（COT）was developed.The influences of finalrolling temperature,cooling rate,and finalcooling temperature on microstructure were investigated.The proper rolling process parameters were obtained through multi-pass thermalsimulation test.The finalrolling temperature is about 820 ℃,the finalcooling temperature is about 600 ℃,and the cooling rate should be controlled between 10 ℃/s and 20 ℃/s.Based on the above analysis of the results,three groups of rolling samples by thermo mechanicalcontrolprocess are prepared.The tensile strength,yield strength,and toughness of the corrosion resistant steelare measured,which meet the requirements of DH36 steel,it can instruct the actualrolling production.The corrosion behaviour is also researched by weight loss and electrochemicalimpedance spectroscopic method,and it is found that the steelhas good corrosion resistance performance,the best one is No.3 steel,the corrosion rate of which is about 1/4 of the accepted criterion.展开更多
In the present work,a nanograin layer of about 150 μm thick was formed on the surface of an interstitial-free（IF） steel via friction stir processing.Then,the fatigue and corrosion behaviors of IF steel with nanogra...In the present work,a nanograin layer of about 150 μm thick was formed on the surface of an interstitial-free（IF） steel via friction stir processing.Then,the fatigue and corrosion behaviors of IF steel with nanograin layer were compared with that of coarse-structure counterpart.More than threefold increase in the hardness was observed due to the formation of nanograin layer.The size of nanograms in the stir zone was within 30-150 nm.This resulted in 50%increase in the fatigue strength of nanostructured specimen.Furthermore,the fracture surfaces were characterized using field emission scanning electron microscopy and scanning electron microscopy.As for the fatigue behavior of nanograin IF steel,the fracture surface was characterized by the formation of nanospacing striations and nanodimples.Besides,the nanograin structure pronounced the passivity and exhibited higher corrosion resistance.展开更多
文摘A robot flexible processing system of shipbuilding profile steel was developed. The system consists of computer integrated control and robot. An off line programming robot was used for marking and cutting of shipbuilding profile steel. In the system the deformation and position error of profile steel can be detected by precise sensors, and figure position coordinate error resulted from profile steel deformation can be compensated by modifying traveling track of robotic arm online. The practical operation results show that the system performance can meet the needs of profile steel processing.
基金Funded by the National Natural Science Foundation of China(No.51575372)
文摘Hot deformation behavior of as-cast Mn18Cr18 N austenitic stainless steel was studied in the temperature range of 950-1200 ℃ and strain rate range of 0.001-1 s^（-1） using isothermal hot compression tests. The true stress-strain curves of the steel were characterized by hardening and subsequent softening and varied with temperatures and strain rates. The hot deformation activation energy of the steel was calculated to be 657.4 k J/mol, which was higher than that of the corresponding wrought steel due to its as-cast coarse columnar grains and heterogeneous structure. Hot processing maps were developed at different plastic strains, which exhibited two domains with peak power dissipation efficiencies at 1150 ℃/0.001 s^（-1） and 1200 ℃/1 s^（-1）, respectively. The corresponding microstructures were analyzed by optical microscopy（OM）, scanning electron microscopy（SEM）, and electron backscatter diffraction（EBSD）. It has been confirmed that dynamic recrystallization（DRX） controlled by dislocation slipping and climbing mechanism occurs in the temperature and strain rate range of 1050-1200 ℃ and 0.001-0.01 s^（-1）; And DRX controlled by twinning mechanism occurs in the temperature and strain rate range of 1100-1200 ℃, 0.1-1 s^（-1）. These two DRX domains can serve as the hot working windows of the as-cast steel at lower strain rates and at higher strain rates, respectively. The processing maps at different strains also exhibit that the instability region decreases with increasing strain. The corresponding microstructures and the less tensile ductility in the instability region imply that the flow instability is attributed to flow localization accelerated by a few layers of very fine recrystallized grains along the original grain boundaries.
基金financial support of the project by National Science Foundation award CMII-1405508
文摘Friction stir processing （FSP） was investigated as a method of repairing cracks in 12 mm thick 304L stainless steel plate. Healing feasibility was demonstrated by processing a tapered crack using a PCBN/W- Re tool with a 25 mm diameter shoulder and a pin length of 6.4 mm. The experiment showed that it was possible to heal a crack that begins narrow and then progressively grows up to a width of 2 mm. Bead on plate experiments were used to find the best parameters for creating a consolidated stir zone with the least amount of hardness difference compared to the base metal. Grain refinement in some specimens resulted in much higher stir zone hardness, compared to base metal, A plot of grain size versus microhardness showed a very strong inverse correlation between grain size and hardness, as expected from the Hall- Perch relationship. Corrosion testing was carried out in order to evaluate the effect of FSP on potential sensitization of the stir zone. After 1000 h of intermittent immersion in 3.5% saline solution at room temperature it was found that no corrosion products formed on the base material controls or on any of the friction stir processed specimens.
基金Item Sponsored by National Basic Research Program of China(2011CB606303)Constructed Project for Key Laboratory of Beijing of China
文摘Hot deformation behavior of a new type of M3∶ 2 high speed steel with niobium addition made by spray forming was investigated based on compression tests in the temperature range of 950-1 150 ℃ and strain rate of 0. 001-10 s^（-1）. A comprehensive constitutive equation was obtained,which could be used to predict the flow stress at different strains. Processing map was developed on the basis of the flow stress data using the principles of dynamic material model. The results showed that the flow curves were in fair agreement with the dynamic recrystallization model. The flow stresses,which were calculated by the comprehensive constitutive equation,agreed well with the test data at low strain rates（ ≤1 s^（-1））. The material constant（ α）,stress exponent（ n） and the hot deformation activation energy（ Q_（HW）） of the new steel were 0. 006 15 MPa^（-1）,4. 81 and 546 kJ·mol^（-1）,respectively. Analysis of the processing map with an observation of microstructures revealed that hot working processes of the steel could be carried out safely in the domain（ T = 1 050-1 150 ℃,ε = 0. 01- 0. 1 s^（-1））with about 33% peak efficiency of power dissipation（ η）. Cracks was expected in two domains at either lower temperatures（ 〈 1 000 ℃） or low strain rates（ 0. 001 s^（-1）） with different cracking mechanisms. Flow localization occurred when the strain rates exceeded 1 s^（-1） at all testing temperatures.
基金supported by the National Natural Science Foundation of China (No.11574159)the Open Fund of the State Key Laboratory of High Field Laser Physics,China (Shanghai Institute of Optics and Fine Mechanics)the Special Research Foundation of the Central University of Nankai University (No.63191108)。
文摘In this paper, we use femtosecond laser pulse to scribe 304 stainless steel foil, detect the Fourier transform infrared spectrum of the sample before and after processing, confirm the "cold processing" and "thermal processing" and their mutual conversion, and determine the "cold processing" parameter window. The ablation threshold and incubation coefficient of 304 stainless steel foil are calculated, and the effects of scanning speed and effective pulse number on the ablation threshold are analyzed. The ANSYS software is used to simulate the radial and axial temperature distributions of the surface on 304 stainless steel foil sample and the heat-affected zone with a femtosecond laser fluence of 10 J/cm2 and an effective number of pulses of 1 200 are obtained. In the aspect of spectral detection, the Fourier transform infrared spectra of the sample before and after processing are measured and two processing mechanisms of "cold processing" and "hot processing" are confirmed, which proves that we can achieve the conversion between "cold processing" and "hot processing" by changing the laser fluence and determine the "cold processing" laser fluence range.
基金The research was financially supported by the National Key Research and Development Program of China(No.2023YFC3707002)Hunan Provincial Innovation Foundation for Postgraduate(No.QL20220069)Postgraduate Innovative Project of Central South University(No.1053320214756).
文摘The steel belt roasting process has the advantages of low cost,small footprint,and high thermal efficiency,making it widely used in the smelting of ferroalloys such as ferrochrome,ferromanganese,and ferroniobium.However,its application in preparing iron ore oxidized pellets has not been sufficiently explored.The optimal thermal process conditions for magnesium-containing oxidized pellet preparation by steel belt roasting machine were investigated based on the roasting properties of high-magnesium iron concentrate and typical iron concentrate.The results indicate that,for the blending scheme of 70 wt.%high-magnesium iron concentrate and 30 wt.%typical iron concentrate,the appropriate preheating temperature for pellets is 950–975℃and the suitable roasting temperature is 1250–1275℃,during which the compressive strength of pellets can exceed 2500 N pellet−1.During the steel belt roasting process,SO_(2)is primarily released in the preheating zone,and the maximum exhaust gas temperature in the roasting zone can reach 637℃.High-temperature sulfur-containing exhaust gas causes oxidation corrosion,sulfide corrosion,and deformation of the steel belt.To enhance the steel belt longevity,it is recommended to appropriately reduce the wind velocity in the preheating zone and roasting zone,while also decreasing the ratio of pellet bed height to hearth layer height.By adopting the system of“low wind velocity,thin pellet bed,fast steel belt speed,”the exhaust gas temperature can be reduced to 463℃.The prepared pellet maintains a compressive strength of 2607 N pellet^(-1)and exhibits excellent metallurgical properties.
基金the support of Swansea University during the pursuit of this research
文摘During this research, experimental rolled homogeneous armour steel was cast, annealed and laser cut to form an appliqué plate. This Martensitic–Bainitic microstructure steel grade was used to test a novel means of engineering lightweight armour. It was determined that a laser cutting speed of 1200 mm/min produced optimum hole formations with limited distortion. The array of holes acts as a double-edged solution, in that they provide weight saving of 45%, providing a protective advantage and increasing the surface area. Data collected were used to generate laser cut-edge hole projections in order to identify the optimum cutting speed, edge condition, cost and deformation performance. These parameters resulted in the generation of a surface, with less stress raising features. This can result in a distribution of stress across the wider surface. Provided that appropriate process parameters are used to generate laser cut edges, then the hardness properties of the surface can be controlled. This is due to compressive residual stresses produced in the near edge region as a result of metallurgical transformations. This way the traverse cutting speed parameter can be adjusted to alter critical surface characteristics and microstructural properties in close proximity to the cut-edge. A relationship was identified between the width of the laser HAZ and the hardness of the cut edge. It is the thickness of the HAZ that is affected by the laser process parameters which can be manipulated with adjusting the traverse cutting speed.
文摘The half-inverted "T" type invisible cover beam is a new type of cover beam with simple and beautiful appearance, but complicated structure. In this paper, the steel bar of the semi-inverted T-shaped invisible cover beam is taken as the research object, and the whole process from data output to optimal design and then to standard processing is studied. By using BIM technology and intelligent steel bending machine, solutions are proposed for the production of complex steel bars.
基金financially supported by the National Key R&D Program of China (No.2017YFB0304000)the National Natural Science Foundation of China (Nos.52074093, 51874102, 51704080, and 51674092)。
文摘In order to promote the intelligent transformation and upgrading of the steel industry, intelligent technology features based on the current situation and challenges of the steel industry are discussed in this paper. Based on both domestic and global research, functional analysis, reasonable positioning, and process optimization of each aspect of steel making are expounded. The current state of molten steel quality and implementation under narrow window control is analyzed. A method for maintaining stability in the narrow window control technology of steel quality is proposed, controlled by factors including composition, temperature, time, cleanliness, and consumption(raw material). Important guidance is provided for the future development of a green and intelligent steel manufacturing process.
基金financially supported by the National Natural Science Foundation of China (No.51734004)the National Key Research and Development Program of China (No.2017YFB0304005)the National Natural Science Foundation of China (No.51474044)。
文摘Against the realistic background of excess production capacity, product structure imbalance, and high material and energy consumption in steel enterprises, the implementation of operation optimization for the steel manufacturing process is essential to reduce the production cost, increase the production or energy efficiency, and improve production management. In this study, the operation optimization problem of the steel manufacturing process, which needed to go through a complex production organization from customers' orders to workshop production, was analyzed. The existing research on the operation optimization techniques, including process simulation, production planning, production scheduling, interface scheduling, and scheduling of auxiliary equipment, was reviewed. The literature review reveals that, although considerable research has been conducted to optimize the operation of steel production, these techniques are usually independent and unsystematic.Therefore, the future work related to operation optimization of the steel manufacturing process based on the integration of multi technologies and the intersection of multi disciplines were summarized.
基金Item Sponsored by National Basic Research Programof China (200002600)
文摘From the viewpoint of systems energy conservation, the influences of material flow on its energy consumption in a steel manufacturing process is an important subject. The quantitative analysis of the relationship between material flow and the energy intensity is useful to save energy in steel industry. Based on the concept of standard material flow diagram, all possible situations of ferric material flow in steel manufacturing process are analyzed. The expressions of the influence of material flow deviated from standard material flow diagram on energy consumption are put forward.
基金Item Sponsored by Fundamental Research Funds for the Central Universities of China(N090602007)National Key Technology Research and Development Program in 11th Five-Year Plan Project of China(2006BAE03A09)
文摘Theoretical minimum and actual specific energy consumptions （SEC） of typical manufacturing process （SMP） were studied. Firstly, a process division of a typical SMP in question was conducted with the theory of SEC analysis. Secondly, an exergy analysis model of a subsystem consisting of several parallel processes and a SEC analysis model of SMP were developed. And finally, based on the analysis models, the SEC of SMP was analyzed by means of the statistical significance. The results show that the SEC of typical SMP comprises the theoretical minimum SEC and the additional SEC derived from the irreversibility~ and the SMP has a theoretical minimum SEC of 6.74 GJ/t and an additional SEC of 19.32 GJ/t, which account for 25.88% and 74.12% of the actual SEC, respectively.
基金Sponsored by National Natural Science Foundation of China(50334020)
文摘The standard material flow diagram in steel manufacturing process was proposed to analyze the influences of various material flows on environmental load of 1tof final product.Two influence factors and reducing measures of environmental load were pointed out.The environmental load was appraised for a typical technological process in a Chinese steel plant.
基金Sponsored by National Natural Science Foundation of China(51271050,51004035)National Science and Technology PillarProgram During 12th Five-Year Plan of China(2012BAE04B02)Fundamental Research Funds for Central Universities ofChina(N100507002)
文摘Texture inhomogeneity usually takes place in ferritic stainless steels due to the lack of phase transformation and recrystallization during hot strip rolling,which can deteriorate the formability of final sheets.In order to work out the way of weakening texture inhomogeneity,conventional hot rolling and warm rolling processes have been carried out with an ultra purified ferritic stainless steel.The results showed that the evolution of through-thickness texture is closely dependent on rolling process,especially for the texture in the center layer.For both conventional and warm rolling processes,shear texture components were formed in the surface layers after hot rolling and annealing;sharp α-fiber and weakγ-fiber with the major component at{111}〈110〉 were developed in both cold rolled sheet surfaces,leading to the formation of inhomogeneousγ-fiber dominated by{111}〈112〉after recrystallization annealing.In the center layer of conventional rolled and annealed bands,strongα-fiber and weakγ-fiber textures were formed;the cold rolled textures were comprised of sharpα-fiber and weakγ-fiber with the major component at{111}〈110〉,and inhomogeneousγ-fiber dominated by{111}〈112〉 was formed after recrystallization annealing.By contrast,in the centre layer of warm rolled bands,the texture was comprised of weakα-fiber and sharpγ-fiber,andγ-fiber became the only component after annealing.The cold rolled texture displayed a sharpγ-fiber with the major component at{111}〈112〉and the intensity ofγ-fiber close to that ofα-fiber,resulting in the formation of a nearly homogeneousγ-fiber recrystallization texture in the center layer of the final sheet.
基金Item Sponsored by National Natural Science Foundation of China (50635030)
文摘The striations on the surface of 3Cr2W8V die steel were processed by laser. The microstructure, hardness, wear resistance and thermal fatigue behavior of the specimens processed by laser were measured. The appearance and mechanism of thermal fatigue crack propagation in the zone processed by laser were observed and discussed. The results show that the wear resistance and thermal fatigue resistance of materials processed by laser are all better than those of the unprocessed material. The processed zone by laser plays a role in baffling wearing process and crack propagation. The pile-nail effect of processed zone is the main factor for improving the wear resistance and thermal fatigue resistance of material.
基金Item Sponsored by High Technology Research and Development Program of China(2007AA04Z161)National Natural Science Foundation of China(50574110,50174061)Key Projects of Chongqing Science and Technology Research Projects(CSTC2011AB3053)
文摘A production planning system is designed for the whole steelmaking process, which includes desulfurization, vanadium extraction, steelmaking and continuous casting processes of Panzhihua Iron and Steel Corporation. The system is composed of modeling module, data interface module, data analysis module, static planning module, re-planning module, plan evaluation module, plan simulation module and human-computer interaction module. The system is connected with the L3 system of steel plant by using the data interface module, which can receive the real time scheduling information to make the static plan and re-plan under production disturbances. The simulation and plan evaluation function of the system can assist decision-maker to check and modify the production plan. The simulation experiments with real process data show that the system can make a feasible, executable, and effective production plan, and deal with primary random disturbances during production process timely.
文摘A siliconizing process to manufacture 6.5% Si steel sheet has been developed. Electric components, such as transformers and reactors are made easily from 6.5% Si steel sheet. However, improved workability is desirable to increase the applications. Therefore the improvement of workability of 6.5% Si steel sheet was investigated, and the results were obtained as follows: (a) workability of 6.5% Si steel sheet is deteriorated by grain boundary oxidization, (b) grain boundary oxidization can be restrained by the addition of C. Workability and magnetic properties of 6.5% Si steel sheet with C addition are discussed. Furthermore, it was found that the workability of high Si steel sheet was improved remarkably by varying the Si content gradient along the thickness without deterioration of high frequency magnetic properties. This newly developed magnetic gradient high Si steel sheet is also discussed.
基金supported by “The World Academy of Sciences,Italy(TWAS)” under the Visiting Researchers Program of TWASUNESCO Associateship Scheme(Ref.3240260896)
文摘The stretch formability of a low carbon steel processed by friction stir processing （FSP） was studied under biaxial loading condition applied by a miniaturized Erichsen test. One-pass FSP decreased the ferritic grain size in the processed zone from 25 μm to about 3 μm, which also caused a remarkable increase in strength values without considerable decrease in formability under uniaxial loading. A coarse-grained （CG） sample before FSP reflected a moderate formability with an Erichsen index （EI） of 2.73 mm. FSP slightly decreased the stretch formability of the sample to 2.66 ram. However, FSP increased the required punch load （FEI） due to the increased strength by grain refinement. FSP reduced considerably the roughness of the free surface of the biaxial stretched samples with reduced orange peel effect. The average roughness value （Ra） decreased from 2.90 in the CG sample down to about 0.65 μm in fine-grained （FG） sample after FSP. It can be concluded that the FG microstructure in low carbon steels sheets or plates used generally in shipbuilding provides a good balance between strength and formability.
基金Funded by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China during the“12th Five-Year Plan”(No.2011BAE25B03)
文摘A new kind of corrosion resistant steelfor cargo oiltanks（COT）was developed.The influences of finalrolling temperature,cooling rate,and finalcooling temperature on microstructure were investigated.The proper rolling process parameters were obtained through multi-pass thermalsimulation test.The finalrolling temperature is about 820 ℃,the finalcooling temperature is about 600 ℃,and the cooling rate should be controlled between 10 ℃/s and 20 ℃/s.Based on the above analysis of the results,three groups of rolling samples by thermo mechanicalcontrolprocess are prepared.The tensile strength,yield strength,and toughness of the corrosion resistant steelare measured,which meet the requirements of DH36 steel,it can instruct the actualrolling production.The corrosion behaviour is also researched by weight loss and electrochemicalimpedance spectroscopic method,and it is found that the steelhas good corrosion resistance performance,the best one is No.3 steel,the corrosion rate of which is about 1/4 of the accepted criterion.
文摘In the present work,a nanograin layer of about 150 μm thick was formed on the surface of an interstitial-free（IF） steel via friction stir processing.Then,the fatigue and corrosion behaviors of IF steel with nanograin layer were compared with that of coarse-structure counterpart.More than threefold increase in the hardness was observed due to the formation of nanograin layer.The size of nanograms in the stir zone was within 30-150 nm.This resulted in 50%increase in the fatigue strength of nanostructured specimen.Furthermore,the fracture surfaces were characterized using field emission scanning electron microscopy and scanning electron microscopy.As for the fatigue behavior of nanograin IF steel,the fracture surface was characterized by the formation of nanospacing striations and nanodimples.Besides,the nanograin structure pronounced the passivity and exhibited higher corrosion resistance.
