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针对5Cr Mn Mo热挤压模具的断裂失效,通过分析模具结构及工作状况,结合金相显微镜、扫描电子显微镜、硬度测试等分析手段对模具的服役状况、宏观形貌和微观组织进行了研究。结果表明:模具的结构及受力特点产生的局部应力集中是模具出现断裂的主要原因,模具表面加工质量差、组织中存在一次碳化物且存在较为严重的带状偏析对模具的失效起到了加剧作用;粗糙表面磨损形成裂纹源,而粗大的碳化物和带状偏析降低了模具的韧性,在巨大的应力集中作用下裂纹迅速扩展,最终导致了模具沿晶脆性断裂。
Aiming at the fracture failure of 5Cr Mn Mo hot extrusion die, the service condition, macro-morphology and microstructure of the die were studied by analyzing the structure and working conditions of the die, combining with the analysis of metallographic microscope, scanning electron microscope and hardness test. The results show that the local stress concentration caused by the structure and force characteristics of the die is the main reason for die breakage. The die surface machining quality is poor, there is a carbides in the structure and serious segmental band segregation has aggravated the die failure The rough surface is worn to form the source of cracks. The coarse carbides and banded segregation reduce the toughness of the die, and the crack expands rapidly under the huge stress concentration, finally leading to the brittle fracture along the die.