随着大型挖掘机中厚板焊接需求的增长,提升中厚板焊接效率愈发关键。以30 mm厚Q355D低合金钢为对象,采用Ø1.2 mm ER50-6焊丝进行多层多道混合气体保护焊,对比分析了两种不同热输入焊接工艺参数(WP-01和WP-02)对焊接接头组织及力学...随着大型挖掘机中厚板焊接需求的增长,提升中厚板焊接效率愈发关键。以30 mm厚Q355D低合金钢为对象,采用Ø1.2 mm ER50-6焊丝进行多层多道混合气体保护焊,对比分析了两种不同热输入焊接工艺参数(WP-01和WP-02)对焊接接头组织及力学性能的影响。结果表明,两种参数下焊缝成形良好,但组织和性能存在差异。WP-01低热输入条件下,焊缝区组织主要为细小的铁素体和贝氏体,过热区出现少量马氏体,晶粒细小;WP-02高热输入条件下,焊缝区贝氏体含量增加,过热区形成粗大铁素体、珠光体和魏氏组织,晶粒粗化。WP-01和WP-2焊接接头均具有较好的抗拉性能,屈服强度和抗拉强度均满足要求。WP-01试样因晶粒细小,冲击韧性显著高于WP-02。然而,WP-01试样在弯曲试验中焊缝根部出现裂纹,不符合合格标准;WP-02试样则无裂纹出现,满足要求。平均抗拉强度为532.5 MPa,WP-02为530 MPa,屈服强度最低值均为360 MPa,焊接接头抗拉性能满足要求。WP-01焊接接头硬度高于WP-02,主要原因是WP-02热输入更高,冷却速度更慢,淬硬倾向降低。综合考虑各项性能指标,大电流焊接工艺WP-02采用高焊接热输入,在保证焊接接头力学性能的同时,显著提高了焊接效率,更适用于Q355D中厚板焊接工艺。展开更多
Magnesium-rare earth(Mg-RE)alloys are pivotal for lightweight applications in aerospace and advanced engineering due to their high specific strength.However,manufacturing large-scale complex components via monolithic ...Magnesium-rare earth(Mg-RE)alloys are pivotal for lightweight applications in aerospace and advanced engineering due to their high specific strength.However,manufacturing large-scale complex components via monolithic casting is challenging owing to defects such as RE oxides and shrinkage porosity,making fusion welding essential for both defect repair and structural joining.This review comprehensively examines recent advances in fusion welding of Mg-RE alloys,with emphasis on the interplay between their unique physicochemical properties and welding metallurgy.Various fusion welding methods suitable for Mg-RE alloys are compared and analyzed.Detailed characterization of joint regions reveals how thermal gradients and cooling rates govern phase evolution,grain morphology,and defect formation.Moreover,welding parameters and heat treatment strategies are systematically discussed for the microstructural configuration,especially for the inherent conflicts between grain coarsening in fusion zone and eutectic dissolution in heat-affected zone.Future research directions are also outlined.By correlating Mg-RE alloy properties with fusion welding processes,this review provides practical insights for designing reliable welded structures in critical applications.展开更多
This study investigates the microstructure and co-precipitation behavior of multicomponent(Ni(Al,Mn)and Cu)nanoparticles in the weld heat-affected zones of high-strength low-carbon steel.Through thermal simulations,th...This study investigates the microstructure and co-precipitation behavior of multicomponent(Ni(Al,Mn)and Cu)nanoparticles in the weld heat-affected zones of high-strength low-carbon steel.Through thermal simulations,the intercritical,fine-grained,and coarsegrained heat-affected zones were systematically characterized to elucidate the interplay between the microstructure,precipitation,and mechanical properties.At a heat input of 30 kJ·cm^(−1),Ni(Al,Mn)nanoparticles dissolve in the intercritical heat-affected zone,followed by dense reprecipitation coupled with significant coarsening of Cu particles during cooling,thereby retaining high strength but reducing impact toughness to(142±10)J(compared to(205±8)J of the base metal).The fine-grained heat-affected zone,under the same heat input,exhibits a refined ferritic-bainite matrix with a few fine Ni(Al,Mn)and slightly coarsened Cu particles,thus enhancing plastic deformation capacity and resulting in superior impact toughness of(196±7)J.Despite complete dissolution of original precipitates at peak temperatures in the coarse-grained heat-affected zone,re-precipitated nanoparticles provide effective strengthening effect,compensating for grain coarsening and dislocation recovery and resulting in an impressive impact toughness of(186±6)J.The toughening mechanism is primarily attributed to the synergistic actions of the matrix,precipitates,and deformation twins.These findings provide mechanistic and quantitative insights for developing processing-microstructure-property relationships in different welding heat-affected zones,and this framework can be further utilized to optimize welding parameters for tailored applications.展开更多
The corrosion resistance of base metal,laser-arc hybrid welded AZ31B magnesium alloys with and without addition of carbon nanotubes(CNTs)was compared.The corrosion behaviors and the underlying improvement mechanism of...The corrosion resistance of base metal,laser-arc hybrid welded AZ31B magnesium alloys with and without addition of carbon nanotubes(CNTs)was compared.The corrosion behaviors and the underlying improvement mechanism of CNTs were systematically investigated.The introduction of CNTs effectively refined the grains,weakened the texture and enhanced the microstructure homogeneity of the weld,which contributed to the enhancement of corrosion resistance.Specifically,the corrosion rates of hydrogen evolution and weight loss of weld decreased by>30%after the addition of CNTs,and the corrosion products were denser due to the formation of Al_(2)O_(3)passive film.The corrosion current density and polarization resistance of weld with addition of CNTs were 1.220μA/cm^(2)and 7155·cm^(2),respectively,in contrast to 2.480μA/cm^(2)and approximately 269.5·cm^(2)for the weld without CNTs.Besides,the content of precipitates in the weld increased from 0.60%to 1.76%after the addition of CNTs,which can release Al^(3+)ions,promoting the formation of a dense Al_(2)O_(3)film that serves to protect the metal matrix from further degradation.展开更多
基金supported by the National Natural Science Foundation of China(No.52405394)the Natural Science Foundation of Shanghai(No.24ZR1436500)+2 种基金the Natural Science Foundation of Chongqing(No.CSTB2024NSCQMSX0677)the Science Innovation Foundation of Shanghai Academy of Spaceflight Technology(No.SAST2024-039)the Startup Fund for Young Faculty at SJTU(No.24X010502880).
文摘Magnesium-rare earth(Mg-RE)alloys are pivotal for lightweight applications in aerospace and advanced engineering due to their high specific strength.However,manufacturing large-scale complex components via monolithic casting is challenging owing to defects such as RE oxides and shrinkage porosity,making fusion welding essential for both defect repair and structural joining.This review comprehensively examines recent advances in fusion welding of Mg-RE alloys,with emphasis on the interplay between their unique physicochemical properties and welding metallurgy.Various fusion welding methods suitable for Mg-RE alloys are compared and analyzed.Detailed characterization of joint regions reveals how thermal gradients and cooling rates govern phase evolution,grain morphology,and defect formation.Moreover,welding parameters and heat treatment strategies are systematically discussed for the microstructural configuration,especially for the inherent conflicts between grain coarsening in fusion zone and eutectic dissolution in heat-affected zone.Future research directions are also outlined.By correlating Mg-RE alloy properties with fusion welding processes,this review provides practical insights for designing reliable welded structures in critical applications.
基金supported by the National Natural Science Foundation of China(No.U2330110)Youth Science Foundation Project(Category A)of Liaoning Province,China(No.2025JH6/101100006).
文摘This study investigates the microstructure and co-precipitation behavior of multicomponent(Ni(Al,Mn)and Cu)nanoparticles in the weld heat-affected zones of high-strength low-carbon steel.Through thermal simulations,the intercritical,fine-grained,and coarsegrained heat-affected zones were systematically characterized to elucidate the interplay between the microstructure,precipitation,and mechanical properties.At a heat input of 30 kJ·cm^(−1),Ni(Al,Mn)nanoparticles dissolve in the intercritical heat-affected zone,followed by dense reprecipitation coupled with significant coarsening of Cu particles during cooling,thereby retaining high strength but reducing impact toughness to(142±10)J(compared to(205±8)J of the base metal).The fine-grained heat-affected zone,under the same heat input,exhibits a refined ferritic-bainite matrix with a few fine Ni(Al,Mn)and slightly coarsened Cu particles,thus enhancing plastic deformation capacity and resulting in superior impact toughness of(196±7)J.Despite complete dissolution of original precipitates at peak temperatures in the coarse-grained heat-affected zone,re-precipitated nanoparticles provide effective strengthening effect,compensating for grain coarsening and dislocation recovery and resulting in an impressive impact toughness of(186±6)J.The toughening mechanism is primarily attributed to the synergistic actions of the matrix,precipitates,and deformation twins.These findings provide mechanistic and quantitative insights for developing processing-microstructure-property relationships in different welding heat-affected zones,and this framework can be further utilized to optimize welding parameters for tailored applications.
基金supported by the National Natural Science Foundation of China(grant nos.52275364 and 52025052)。
文摘The corrosion resistance of base metal,laser-arc hybrid welded AZ31B magnesium alloys with and without addition of carbon nanotubes(CNTs)was compared.The corrosion behaviors and the underlying improvement mechanism of CNTs were systematically investigated.The introduction of CNTs effectively refined the grains,weakened the texture and enhanced the microstructure homogeneity of the weld,which contributed to the enhancement of corrosion resistance.Specifically,the corrosion rates of hydrogen evolution and weight loss of weld decreased by>30%after the addition of CNTs,and the corrosion products were denser due to the formation of Al_(2)O_(3)passive film.The corrosion current density and polarization resistance of weld with addition of CNTs were 1.220μA/cm^(2)and 7155·cm^(2),respectively,in contrast to 2.480μA/cm^(2)and approximately 269.5·cm^(2)for the weld without CNTs.Besides,the content of precipitates in the weld increased from 0.60%to 1.76%after the addition of CNTs,which can release Al^(3+)ions,promoting the formation of a dense Al_(2)O_(3)film that serves to protect the metal matrix from further degradation.
