采用拉伸试验机、光学显微镜、扫描电镜及能谱仪等分析了摩托车车架用钢伸长率不合格的原因, 并在此基础上给出了相应的改进工艺措施。结果表明: 摩托车车架用钢伸长率不合格的主要原因为拉伸断口区域分层严重、拉伸断口上存在大量非金属氧化物及硅钙酸盐夹杂物以及分层和夹杂物二者共存; 通过优化炼钢工艺, 可有效消除铸坯中心偏析和降低夹杂物等级, 增大轧制压缩比可减少或防止拉伸时出现的断口分层; 采取高温加热(1 180~1 250 ℃)、高温开轧(大于1 100 ℃)、高温终轧(870~850 ℃)和低温卷取(610~640 ℃)可改善摩托车车架用钢的组织和力学性能, 使其伸长率符合相关要求。

The reasons for elongation disqualification for the steel used for motorcycle frame were studied by means of tensile testing and optical microscopy, scanning electron microscopy and energy diffraction. The results show that the main reasons for elongation disqualification for the steel used for motorcycle frame were serious layering in tensile fracture, a large number of nonmetal oxide and silicon calcium acid salt inclusions existing in tensile fracture, as well as the layering and inclusions coexistence. The slab center segregation could be effectively eliminated and the level of inclusions could be reduced by optimizing the steelmaking process. Increasing the rolling compression ratio could reduce or prevent fracture layering. Some measures, including high temperature heating at 1 180-1 250 ℃, high temperature rolling at over 1 100 ℃ and high temperature finish rolling at 870-870 ℃ as well as low temperature coiling at 610-640 ℃, could improve microstructure and mechanical properties of the steel used for motorcycle frame, and made its elongation meet related requirements.