低密度钢连杆锻造微裂纹分析
Analysis on cracking of the low density steel during forging forming process
低密度钢是近几十年汽车零部件用钢的研究热点，也是汽车轻量化的发展趋势。连杆作为发动机动力输出的关键零部件之一，直接影响和决定了发动机的耐久性和可靠性。本文通过微观组织、断口形貌观察及热塑性研究，对Fe-22Mn-9Al-0.6C低密度钢在连杆锻造过程中产生的微裂纹进行分析。发现其锻后组织为奥氏体和长条状的δ-铁素体。因此，锻造时 δ-铁素体和γ两相界面产生的应力差较大，使两相界面开裂。同时当锻造温度降至850~900℃时，由于形成了硬而脆的 B2 结构的( Fe，Mn) Al相，热塑性降低，从而导致连杆大头端与小头端产生微裂纹。
In recent years, the low density steel has attracted more attention as steel for automotive components and is one trend for automotive lightweight. . The connecting rod is as one of the major contributors to engine power output, which controls engine’s longevity and dependability. This study investigates the microcracks casued in the Fe-22Mn-9Al-0.6C low density steel during the forging forming process through the examination of microstructure, fracture morphology, and thermoplasticity. It is found that the microstructure after forging is austenite and strip δ-ferrite . As a result, during forging, there is a significant stress difference in the interface of the δ-ferrite and γ phases, which causes the interface crack. Moreover, the thermoplasticity diminishes owing to the production of the hard and brittle (Fe,Mn) Al phase with B2 structure when the forging temperature falls to 850 °C~900 °C, which causes microcracks at the connecting rod's big end and small end.
周逸浩;满廷慧;韦习成;董瀚;
上海大学 材料科学与工程,上海 200438;上海大学 材料科学与工程,上海 200438##上海大学（浙江）高端装备基础件材料研究院,浙江 314100;上海大学 材料科学与工程,上海 200438##上海大学（浙江）高端装备基础件材料研究院,浙江 314100;上海大学 材料科学与工程,上海 200438##上海大学（浙江）高端装备基础件材料研究院,浙江 314100;
TK4
low density steel connecting rod forging forming thermoplasticity B2 phase
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