汽车用BH340钢烘烤硬化性能的教学实验研究

Study on teaching experiments by baking hardening performance of BH340 steel for automobiles

在材料分析的实践教学环节中引入新型汽车用低碳钢板力学性能实验,实验研究BH340钢的烘烤硬化性能,结合实际生产中车身覆盖件大变形成形的特点,进行17%的预变形量及后续170℃、30min的烘烤处理,利用扫描电镜摄取了断口形貌并进行了硬度测试分析。结果表明,BH340钢经较大预变形并烘烤后显示出较强的应变时效效应,塑性与韧性明显下降,屈服强度及表面硬度均有所提高,而且在多次伸长类变形中存在破裂危险点转移的倾向。

Mechanical properties tests of novel low-carbon steel for automobiles are brought into practical teaching on material analysis.Based on characteristics of large deformation in automobile panel forming,the study on baking hardening performance of BH340 steel is performed.About 17% pre-deformation and subsequent the baking treatment at 170 ℃ in 30 min are carried out.The scanning electron microscope is utilized to observe fracture of the samples,and in the meantime,the hardness testing is carried out.The resulfs show that BH340 steel displays relatively strong strain aging effect after relatively large deformation and subsequent baking treatment,and in the meanwhile,plasticity and toughness decrease while yield stress and hardness increase.What＇s more,there exits the trend of crack point transfer in the repeatedly tensile-type of deformation.