The high strength steel Q550D used in engineering machinery was developed by composition optimization and rolling process optimization in Baotou Steel.The welding performance of Q550D high strength steel was analyzed by the maximum hardness in heat affected zone, the implant test and the Y-slit type cracking test, and the results show that : The highest hardness (HV10) for heat affected zone of Q550D steel plate is 297.The result of implant test shows that under the condition of moderate restraint, Q550D steel plate with 20 mm thickness was welded by HS-70 welding stick, there is no crack without preheating.At the same time, the Y-slit type cracking test shows that under the condition of no preheating to weld Q550D steel plate with 20 mm thickness, the surface crack rate and the cross section crack rate of the two groups of samples are zero.%包钢通过成分优化和轧制工艺的优化研制了工程机械用高强度钢Q550D. 通过热影响区最高硬度、插销试验、斜Y坡口焊接裂纹试验对Q550D高强度钢的焊接性能进行分析,研究结果表明:Q550D钢板热影响区最高硬度(HV10)为297.插销试验结果表明,在中等拘束条件下,采用HS-70焊丝焊接20 mm厚Q550D钢板,不预热没有裂纹的产生.同时斜Y坡口焊接裂纹试验表明对于20 mm厚Q550D钢板,在不预热条件下焊接,两组试样表面裂纹率和断面裂纹率均为零.
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