含钛微合金钢低温冲击韧性波动的原因与改进

针对含钛微合金钢板生产过程中出现的低温冲击韧性波动的现象,从化学成分、冲击试样断口形貌、金相组织及夹杂物等方面分析了主要影响因素。结果表明,含钛微合金钢板的低温冲击功波动大主要与钢板有害元素含量、内部组织、夹杂物尺寸大小和分布等因素有关。为此对钢的化学成分进行优化调整,适当降低碳质量分数,严格控制磷、氮、氢等有害元素质量分数以及加热工艺参数细化组织,适当加快轧后的冷速可有效改善带状组织,提升钢板的低温冲击性能,提高产品的合格率。

Cause analysis and improvement of undulation of low temperature impact property for Ti microalloyed steel

In view of the problem of the undulation of low temperature impact toughness in the production of Ti microalloyed plate, the corresponding experimental studies were carried out. The main influence factors of the undulation of low temperature impact toughness were analyzed from the aspects of the chemical component, fracture morphology of the impact specimen, microstructure and inclusions. The results showed that the content of harmful elements, internal structure, size and distribution of inclusions etc. were the major causes of the big undulation of low temperature impact toughness. Therefore, the composition was optimized by appropriately reducing the C mass fraction and strictly controlling the mass fraction of harmful elements P, N, H etc., the parameters of the heating process were carefully controlled to refine the microstructure, and the cooling rate was accelerated after rolling to effectively weak the banded structure and so on, which can obvious improve the low temperature impact toughness and product qualification rate.