高铁用进口EA4T钢车轴的组织和力学性能

研究了高铁用进口EA4T钢车轴的显微组织和力学性能,分析了组织和力学性能的均匀性。结果表明:车轴中存在CaS、Al2O3及少量硅酸盐等非金属夹杂物,沿表面至心部夹杂物的数量增多;车轴不同位置的显微组织均为回火马氏体、贝氏体和少量先共析铁素体,自表面向心部先共析铁素体的尺寸增大、数量增多,组织不均匀;车轴的拉伸性能和硬度均满足标准要求,但心部因先共析铁素体含量较多,抗拉强度明显较低;车轴纵向存在带状组织,因此其横向冲击韧性较差;车轴试样的拉伸断口存在较多小而深的韧窝,说明其塑性良好,断裂方式为韧性断裂,而冲击断口存在明显的河流花样和韧窝,断裂方式为脆韧混合断裂。

Microstructure and Mechanical Properties of Imported EA4T Steel Axle for High-Speed Railway

Microstructure and mechanical properties of imported EA4 Tsteel axle for high-speed railway were investigated,and uniformity of the microstructure and mechanical properties was analyzed.The results show that non-metallic inclusions,including CaS,Al2 O3 and a small amount of silicate,were found in the axle,and the number of inclusions increased from the surface to the core.The microstructures at different positions in the axle all consisted of tempered martensite,bainite and a small amount of proeutectoid ferrite;the size and number of the proeutectoid ferrite increased from the surface to the core.The microstructure was uneven.The tensile properties and hardness of the axle met the standard requirements.The tensile strength at the core was obviously lower due to higher content of the proeutectoid ferrite.Banded structure was observed in the longitudinal direction of the axle,and therefore the transverse impact toughness was relatively low.The tensile fracture of the axle sample showed relatively small and deep dimples,indicating good plasticity;the tensile fracture mode was ductile fracture.The impact fracture had obvious river patterns and dimples,and the fracture mode was brittle-ductile mixed fracture.