For a long time,the deep penetration of laser beam welding(LBW)of ultra-thick titanium alloys used for super large-sized equipment has always been a significant challenge in engineering fields due to the dispersion of...For a long time,the deep penetration of laser beam welding(LBW)of ultra-thick titanium alloys used for super large-sized equipment has always been a significant challenge in engineering fields due to the dispersion of most laser beam energy in air.In this study,we designed the good matching of laser beam and welding parameters at a high power of 30 kW and a low ambient pressure of 0.3 Pa,and the deep weld penetration(95 mm)of Ti-6Al-4V alloy ultra-thick plates was first time achieved via vacuum LBW(VLBW).It was much larger than ever reported in titanium alloy VLBW joints.During VLBW,the plasma plume was gradually inhibited with the decrease in ambient pressures and basically disappeared below 101 Pa.The lower ambient pressure improved the stability of the molten pool,and enhanced the energy absorption inside the keyhole,thereby largely increasing the weld penetration.After VLBW,the contents of the impurity gas elements(N,H,and O)in the joint hardly changed.A relatively uniform welding temperature and cooling rate throughout the thickness resulted in a relatively homogeneous microstructure in the joint,leading to uniform hardness,strength,and toughness throughout the thickness.The secondaryα(α_(s))andαmartensite precipitated in the heat-affected zone and fusion zone,respectively.They increased theα_(s)/βand α/βinterfaces,resulting in their higher microhardness values than those in the base material(BM).In this case,the VLBW joint reached 987 MPa in strength,achieving equal strength welding to the BM.Furthermore,the impact energy(28 J)and fracture toughness(82.4 MPa m^(1/2))of the joint both could reach over 90%of the BM,achieving excellent strength-toughness matching.This study provides a new way for the high-property deep penetration welding of ultra-thick titanium alloys for large-sized components.展开更多
It is rather difficult for titanium alloy ultra-thick plates to achieve superior weld formation and excellent mechanical properties along the weld penetration direction due to the large fluctuations of the molten pool...It is rather difficult for titanium alloy ultra-thick plates to achieve superior weld formation and excellent mechanical properties along the weld penetration direction due to the large fluctuations of the molten pool,largely limiting their engineering application.In this study,106-mm-thick Ti-6Al-4V ELI alloy plates were successfully butt welded via electron beam welding(EBW).The defect-free EBW joint with full penetration was obtained.The precipitated secondary α(α_(s))in heat affected zone(HAZ),αlamellae in fusion line(FL)and α′martensite in fusion zone(FZ)increased the α_(s)/β,α/β and α′/β interfaces,respectively,resulting in the higher microhardness and impact energy values(57 J in the HAZ,62 J in the FL and 51.9 J in the FZ)than those in the base material(BM).The impact energy of the joint in this study was higher than that for Ti-6Al-4V ELI alloy joints as reported,which was mainly attributed to the formation of the relatively thickerαphase and finer interlamellar spacing in this study,enhancing the resistance to crack propagation.Furthermore,the average fracture toughness(90.2 MPa m^(1/2))of the FZ was higher than that of the BM(74.2 MPa m^(1/2)).This study provides references for the welding application of titanium alloy ultra-thick plates in the manufacture of large-sized components.展开更多
Strong metal/non-polar plastic dissimilar joints are highly demanded for the lightweight design in many fields,which,however,are rather challenging to achieve directly via welding.In this study,we designed a laser pro...Strong metal/non-polar plastic dissimilar joints are highly demanded for the lightweight design in many fields,which,however,are rather challenging to achieve directly via welding.In this study,we designed a laser processing pretreatment on the Al alloy to create a deep porous Al surface structure,which was successfully joined to the polypropylene(PP) via friction spot welding.A maximum joint strength of29 MPa was achieved,the same as that of the base PP(i.e.the joint efficiency reached 100%),much larger than ever reported.The joining mechanism of the Al alloy and the PP was mainly attributed to the large mechanical interlocking effect between the laser processed Al porous structure and the re-solidified PP and the formation of chemical bond at the interface.The deep porous Al surface structure modified by laser processing largely changed the Al-PP reaction feature.The evidence of the C-O-Al chemical bond was first time found at the non-polar plastic/Al joint interface,which was the reaction result between the oxide on the Al alloy surface and thermal oxidization products of the PP during welding.This study provides a new way for enhancing metal-plastic joints via surface laser treatment techniques.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2023YFC2810700)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2021193)+2 种基金the Liaoning Province Excellent Youth Foundation(No.2024JH3/10200021)the Liaoning Revitalization Talents Program(No.XLYC2403094)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.PTYQ2024YZ0009).
文摘For a long time,the deep penetration of laser beam welding(LBW)of ultra-thick titanium alloys used for super large-sized equipment has always been a significant challenge in engineering fields due to the dispersion of most laser beam energy in air.In this study,we designed the good matching of laser beam and welding parameters at a high power of 30 kW and a low ambient pressure of 0.3 Pa,and the deep weld penetration(95 mm)of Ti-6Al-4V alloy ultra-thick plates was first time achieved via vacuum LBW(VLBW).It was much larger than ever reported in titanium alloy VLBW joints.During VLBW,the plasma plume was gradually inhibited with the decrease in ambient pressures and basically disappeared below 101 Pa.The lower ambient pressure improved the stability of the molten pool,and enhanced the energy absorption inside the keyhole,thereby largely increasing the weld penetration.After VLBW,the contents of the impurity gas elements(N,H,and O)in the joint hardly changed.A relatively uniform welding temperature and cooling rate throughout the thickness resulted in a relatively homogeneous microstructure in the joint,leading to uniform hardness,strength,and toughness throughout the thickness.The secondaryα(α_(s))andαmartensite precipitated in the heat-affected zone and fusion zone,respectively.They increased theα_(s)/βand α/βinterfaces,resulting in their higher microhardness values than those in the base material(BM).In this case,the VLBW joint reached 987 MPa in strength,achieving equal strength welding to the BM.Furthermore,the impact energy(28 J)and fracture toughness(82.4 MPa m^(1/2))of the joint both could reach over 90%of the BM,achieving excellent strength-toughness matching.This study provides a new way for the high-property deep penetration welding of ultra-thick titanium alloys for large-sized components.
基金supported by the National Key Research and Development Program of China(No.2023YFC2810700)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2021193)+2 种基金the Liaoning Province Excellent Youth Foundation(No.2024JH3/10200021)the Liaoning Revitalization Talents Program(No.XLYC2403094)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.PTYQ2024YZ0009).
文摘It is rather difficult for titanium alloy ultra-thick plates to achieve superior weld formation and excellent mechanical properties along the weld penetration direction due to the large fluctuations of the molten pool,largely limiting their engineering application.In this study,106-mm-thick Ti-6Al-4V ELI alloy plates were successfully butt welded via electron beam welding(EBW).The defect-free EBW joint with full penetration was obtained.The precipitated secondary α(α_(s))in heat affected zone(HAZ),αlamellae in fusion line(FL)and α′martensite in fusion zone(FZ)increased the α_(s)/β,α/β and α′/β interfaces,respectively,resulting in the higher microhardness and impact energy values(57 J in the HAZ,62 J in the FL and 51.9 J in the FZ)than those in the base material(BM).The impact energy of the joint in this study was higher than that for Ti-6Al-4V ELI alloy joints as reported,which was mainly attributed to the formation of the relatively thickerαphase and finer interlamellar spacing in this study,enhancing the resistance to crack propagation.Furthermore,the average fracture toughness(90.2 MPa m^(1/2))of the FZ was higher than that of the BM(74.2 MPa m^(1/2)).This study provides references for the welding application of titanium alloy ultra-thick plates in the manufacture of large-sized components.
基金supported by the National Natural Science Foundation of China (Nos. 51975553 and 51931009)IMR SYNL-T.S. Kê Research Fellowship。
文摘Strong metal/non-polar plastic dissimilar joints are highly demanded for the lightweight design in many fields,which,however,are rather challenging to achieve directly via welding.In this study,we designed a laser processing pretreatment on the Al alloy to create a deep porous Al surface structure,which was successfully joined to the polypropylene(PP) via friction spot welding.A maximum joint strength of29 MPa was achieved,the same as that of the base PP(i.e.the joint efficiency reached 100%),much larger than ever reported.The joining mechanism of the Al alloy and the PP was mainly attributed to the large mechanical interlocking effect between the laser processed Al porous structure and the re-solidified PP and the formation of chemical bond at the interface.The deep porous Al surface structure modified by laser processing largely changed the Al-PP reaction feature.The evidence of the C-O-Al chemical bond was first time found at the non-polar plastic/Al joint interface,which was the reaction result between the oxide on the Al alloy surface and thermal oxidization products of the PP during welding.This study provides a new way for enhancing metal-plastic joints via surface laser treatment techniques.
