高碳钢中珠光体片层与先共析铁素体对断裂韧性的影响

Effect of interlamellar pearlite spacing and pro-eutectoidferrite on fracture toughness of high-carbon steel

以珠光体钢为研究对象,在不同盐浴温度下等温获得不同特征的珠光体组织。进行了力学性能测试与准静态断裂韧性(J0.2BL)测试,在扫描电子显微镜(SEM)下观察了微观组织与裂纹扩展路径。研究结果表明,珠光体片层间距与铁素体量对断裂韧性具有显著影响,裂纹扩展阻力由珠光体片层间距以及先共析铁素体含量共同决定,根据不同组织对裂纹扩展阻力的贡献值珠光体钢裂纹扩展总阻力可用表达式δ(SUM)=k'δ(P)+kδ(F)来进行描述,随着等温温度的增加,珠光体片层间距与先共析铁素体量增加,珠光体钢裂纹扩展总阻力呈先上升后下降的趋势,与J0.2BL实验结果具有一致的趋势。

Pearlite microstructure in a high carbon steel after different heat treatments was obtained. The tensile properties and quasi-static fracture toughness（ J0. 2BL） of the steel were tested,and microstructure and crack propagation path were observed by using scanning electron microscope（ SEM）. The results indicate that interlamellar spacing and the pro-eutectoid ferrite have obvious effect on fracture toughness of the steel. The crack propagation resistance is controlled by the interlamellar pearlite spacing and pro-eutectoidferrite. The crack propagation resistance can be described by equation： δ（ SUM） = k＇δ（ P） ＋ kδ（ F）. With the increasing of isothermal temperatures,the interlamellar pearlite spacing and the content of pro-eutectoid ferrite increase,and the crack propagation resistance of the pearlitic steel increases firstly,and then decreases. The result has a good consistance with that of the experimental results of the quasi-static fracture toughness（ J0. 2BL） measurement.