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采用焊接热模拟的方法，模拟了高强贝氏体钢和Ｕ７４钢轨钢过热区在正火和回人状态下的组织，结果表明：高强贝氏体钢过热区在两种热处理状态下的组织均为粒状贝氏体，而钢轨钢过热区为珠光体加少量铁素体，拉伸试验结果表明，贝氏体钢过热区在正火和回火状态下，其强度与贝氏体钢母材相当，延伸率大于１２％，与母材匹配，钢轨钢过热区的强度与钢轨相当．但延伸率低．断口分析表明，贝氏体钢过热区断口呈韧窝状，为延性断裂，而钢轨钢过热区断口平整，呈条带状，条带间存在着长条状ＭｎＳ夹杂，降低了钢轨钢过热区延性．
The welding heat simulation method is used to simulate the microstructure of high strength bainite steel and U74 steel overheated zone in normalizing and returning state. The results show that the microstructure of high strength bainite steel in both heat treatment conditions As granular bainite, and rail overheating zone for the pearlite plus a small amount of ferrite, tensile test results show that bainite overheated zone in the normalized and tempered state, the strength and bainitic steel base metal Equivalent, elongation greater than 12%, matched with the base metal, rail steel overheating zone strength and rail quite. But low elongation. Fracture analysis shows that the fracture of bainite steel overheat zone is dimpled, which is ductile fracture, while the fracture of overheat zone of rail steel is flat and strip-like, with long strip-shaped MnS inclusions in the strip, which reduces the overheat zone of rail steel Ductility.