晶粒尺寸对注射成形HK30耐热奥氏体不锈钢力学性能的影响

Effect of Grain Size on Mechanical Properties of Injection Molded HK30 Heat-resistant Austenitic Stainless Steel

以 HK30 不锈钢粉末为原料,采用注射成形工艺,在 1290 ℃下烧结制备 HK30 不锈钢,对 HK30 不锈钢在不同保温温度(900~1250 ℃)和保温时间(3~12 h)下的奥氏体晶粒长大规律进行了研究。结果表明:奥氏体晶粒尺寸随保温温度升高呈指数关系长大,随保温时间的增加呈近似抛物线形式长大;基于已有的 sellars 模型,通过对实验数据进行非线性回归得到了 HK30 不锈钢钢奥氏体晶粒长大规律的数学模型;对不同晶粒尺寸的 HK30 不锈钢试样进行室温及 650 ℃拉伸性能测试,结果表明:在常温下随着晶粒尺寸的增加,粗晶粒降低作用显著,试样的拉伸强度由 621.83 MPa 降至 505.755 MPa,屈服强度由 315.85 MPa 降至 282.988 MPa,延伸率由 43.29 %降至 37.52 %,但在高温下拉伸强度及屈服强度降低并不显著,在实际应用中建议晶粒尺寸不超过 65 μm 为宜。

The HK30 stainless steel was prepared by injection molding process, the austenite grain growth of HK30 stainless steel at different holding temperatures (900~1250 °C) and holding time (3~12 h) was studied. The results show that the austenite grain size grows exponentially with the increase of holding temperature, and grows in the approximate parabola form with the increase of holding time. Based on the existing sellars model, the mathematical model of austenite grain growth in HK30 stainless steel is obtained by nonlinear regression of experimental data. The tensile properties of HK30 stainless steel samples with different grain sizes were tested at room temperature and 650 °C. The results show that with the increase of grain size at normal temperature, the coarse grain reduction effect is significant. The tensile strength of the sample decreases from 621.83 MPa to 505.755 MPa, the yield strength decreases from 315.85 MPa to 282.988 MPa, and the elongation decreases from 43.29 % to 37.52 %. However, the tensile strength and yield strength decrease are not significant at high temperatures. In practical applications, it is recommended that the grain size not exceed 65 μm.