高强韧轨道交通用钢药芯焊丝的力学性能及组织分析

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2×106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.

Analysis of mechanical properties and microstructure of flux-cored wire for railway transportation equipment steel

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 flux-cored 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 1.1,1.6 and 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.