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为了解决50mm厚高强度低合金钢Q550D的低温冲击值不稳定的问题,对其合金成分进行了调整试验研究,结果表明,新成分50mm厚Q550D成品钢板强度稳定,伸长率较好,1/4厚度处的-20℃低温纵向冲击值都稳定在239～324J之间,试验批次一次性性能合格率达到100%,成品组织得到了明显改善,吨钢成本也有很大的降低,说明高强度低合金钢中的析出强化元素和固溶强化元素应视钢水冶炼情况及轧制工艺进行适当添加。同时对本钢种低温冲击不稳定争论较大的淬透性问题进行了端淬试验研究,结果表明,原成分钢的淬透性比新成分钢的淬透性要好,说明原成分钢板低温冲击值不稳定并不是钢的淬透性不好,而是成分设计不合理。
In order to solve the problem of instability of the low temperature impact value of 50mm thick high strength low alloy steel Q550D, the alloy components were adjusted and tested. The results show that the new composition of 50mm thick Q550D finished steel plate has the advantages of stable strength and good elongation, 4 at -20 ℃ low temperature longitudinal impact values are stable at 239 ~ 324J, the test batch disposable performance rate of 100%, the finished product has been significantly improved, the cost per ton of steel has also greatly reduced, indicating that the high Strength of low-alloy steel precipitation strengthening elements and solid solution strengthening elements should be subject to molten steel smelting conditions and rolling process for proper addition. At the same time, the end quenching of the hardenability of low temperature impact instability of the present steel was studied. The results show that the hardenability of the original steel is better than the hardenability of the new steel, which shows that the low temperature impact value Instability is not steel hardenability is not good, but the composition design is not reasonable.