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某厂试制的Fe-25Mn-3Si-3Al TWIP钢电渣重熔锭在高温锻压过程中出现开裂。利用Gleeble3500热模拟试验机研究了Fe-25Mn-3Si-3Al TWIP钢的高温力学性能,得出第Ⅰ脆性区间为1 250℃到熔点,第Ⅲ脆性区间为650~800℃。利用扫描电镜(SEM)观察不同拉伸温度下断口的宏观形貌,光学显微镜观察断口附近的组织形貌,电子探针(EPMA)测定拉伸试样的偏析状态,电子背散射衍射(EBSD)试验分析研究试样中的相组成,以此来确定Fe-25Mn-3Si-3Al TWIP钢的断裂机制。研究表明,在第Ⅲ脆性区间,TWIP钢的断裂形式为沿晶和穿晶的混合断裂,其脆性断裂的主要原因为铁素体的析出和晶界偏析。动态再结晶对提高TWIP钢的高温塑性具有决定性的影响。在今后的生产中应优化电渣重熔和热加工的工艺参数以避免裂纹的产生。
A factory trial of Fe-25Mn-3Si-3Al TWIP steel electroslag remelting ingot cracking occurs during high temperature forging. The mechanical properties at high temperature of Fe-25Mn-3Si-3Al TWIP steel were studied by Gleeble3500 thermal simulation tester. The results show that the first brittleness zone Ⅰ is from 1 250 ℃ to the melting point and the third is from 650 ℃ to 800 ℃. The morphology of the fracture at different stretching temperatures was observed by scanning electron microscopy (SEM). The morphology of the fracture near the fracture was observed by light microscopy. The segregation state of the tensile specimen by electron probe (EPMA), the electron backscatter diffraction (EBSD) The fracture mechanism of Fe-25Mn-3Si-3Al TWIP steel was determined by analyzing the phase composition in the sample. The results show that in the third brittle interval, the fracture mode of TWIP steel is intergranular and transgranular mixed fracture. The main reason of brittle fracture is the precipitation of ferrite and segregation of grain boundaries. Dynamic recrystallization has decisive influence on the high temperature plasticity of TWIP steel. In the future production should be optimized electroslag remelting and thermal processing of the process parameters to avoid the generation of cracks.