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通过高温拉伸试验,研究了变形温度对铸态及热加工态奥氏体不锈钢Cr15Mn9Cu2NiN热塑性的影响。结果表明,在1 250℃时,铸态与热加工态试样的断面收缩率均在85%以上;随着变形温度的降低铸态试样的塑性迅速下降,而热加工态试样则无明显变化;变形温度降至900℃时,铸态试样的断面收缩率只有45%左右。分析认为,铸态试样中具有明显结晶取向的柱状晶,随着变形温度的降低,在变形过程中会迅速强化,使得晶粒间的变形协调能力迅速下降,导致在晶界或相界等较薄弱处产生应力集中,进而引起裂纹的形核及塑性的快速降低;而热轧板试样中为细小的等轴晶,变形协调能力强,变形时,应变会均匀地分布在每个晶粒上,使得其热塑性较高。
Through the high temperature tensile test, the influence of deformation temperature on the thermoplasticity of as-cast austenitic stainless steel Cr15Mn9Cu2NiN was studied. The results show that the cross-sectional shrinkage of as-cast and hot-worked specimens is above 85% at 1 250 ℃. The plasticity of as-cast specimens decreases rapidly with the decrease of deformation temperature, Significant changes; deformation temperature dropped to 900 ℃, the as-cast section of the sample shrinkage rate of only about 45%. The analysis shows that the columnar crystals with obvious crystal orientation in the as-cast sample rapidly strengthen with the decrease of the deformation temperature during the deformation process, resulting in the rapid decrease of the deformation coordination ability between the grains, resulting in the grain boundary or phase boundary The weaker place produces stress concentration, and then leads to rapid crack nucleation and plastic reduction; and hot-rolled plate sample is a small equiaxed grain, deformation coordination ability, deformation, the strain will be evenly distributed in each crystal Granule, making it more thermoplastic.