U71Mn、U75V和U78CrV钢轨在线热处理后性能改善比较

Comparison of property improvement of U71Mn,U75V and U78CrV rail steels by online heat treatment

采用强度、硬度测试和金相显微镜及扫描电镜观察,对热轧态和在线热处理态的U71Mn、U75V和U78Cr V钢轨的力学性能和显微组织进行分析。结果表明,钢轨的显微组织均为珠光体+少量铁素体,热轧态的珠光体片层间距较大,在线热处理后珠光体片层间距变小,性能得到改善。从强度和硬度指标分析,在线热处理对U75V钢轨的性能改善效果最佳,从强塑积指标分析,在线热处理对U78Cr V钢轨的性能改善效果最佳。U78Cr V钢轨在线热处理钢轨的珠光体片层间距最小,且具有较好的综合性能。

Microstructure and mechanical properties of U71 Mn,U75V and U78 Cr Vrail steels as-hot-rolled and in online heat treatment state were analyzed by means of strength test,hardness test and observation of metallographic microscope and scanning electron microscopy.The results show that microstructure of the rail steels are all composed of pearlite with a small amount of ferrite,the pearlite interlamellar spacing as-hot-rolled is larger than that of after online heat treatment,the microstructure is refined and the mechanical properties are improved.From the index of strength and hardness,the U75 V rail steel after on-line heat treatment has preferable improving effect,and from the index of product of strength and elongation,the U78 Cr V rail steel has the best improving effect.Pearlite interlamellar spacing of the U78 Cr Vrail steel after online heat treatment is the smallest among the tested rail steels,and its combination of strength and ductility is preferable.