高强韧轨道交通用钢药芯焊丝的力学性能及组织分析

Analysis of mechanical properties and microstructure of fluxcored wire for railway transportation equipment steel

针对轨道交通装备用屈服强度为450 MPa级低合金高强钢研制了一种焊接工艺性能优良、具有高强韧性、良好抗疲劳性能的药芯焊丝,并对研制的药芯焊丝熔敷金属拉伸、低温冲击韧性和疲劳强度等力学性能及组织进行了分析.结果表明,研制的药芯焊丝成分设计合理,焊缝组织以针状铁素体和粒状贝氏体为主,晶粒细小,有效提高了焊缝的强韧性,使焊缝具有优良的低温韧性和疲劳性能.药芯焊丝熔敷金属的抗拉强度达到620 MPa,-40℃低温韧性夏比冲击吸收功为96 J,指定寿命为2×10~6次循环下的疲劳极限为354 MPa,分别是设计目标值的1.1倍、1.6倍和2.2倍,能够满足轨道交通装备用屈服强度为450 MPa级低合金高强钢的焊接需求.

Aiming at 450 MPa level low-alloy high-strength steel for railway transportation equipment,a flux-cored wire with excellent welding performance,high strength toughness and good fatigue resistance was developed.The tensile property,low-temperature impact toughness,fatigue strength and microstructure of fluxcored wire deposited metal were analyzed.The results indicate that the composition of flux-cored wire is designed reasonaby.The microstructures are mainly acicular ferrite and granular bainite.The grain size is fine.Therefore the strength toughness is effectively improved and the excellent low-temperature toughness and fatigue strength are obtained.The tensile strength,low-temperature impact toughness at-40℃and fatigue strength of flux-cored wire deposited metal achieve 620 MPa,96 J and 354 MPa,which are 1.1,1.6and 2.2 times of the target value of design respectively.The developed flux-cored wire can meet the welding requirement of 450 MPa level low-alloy high-strength steel for railway transportation equipment.