烧结温度对30Cr粉末冶金低合金钢组织与性能的影响

采用气雾化制粉-热压烧结工艺制备30Cr粉末冶金低合金钢，研究烧结温度对其显微组织及力学性能的影响。采用扫描电镜、洛氏硬度计、力学试验机等对不同烧结温度下获得的样品进行分析。结果表明:在1100~1200℃的烧结温度下，随着烧结温度的升高，30Cr粉末冶金低合金钢烧结样品的孔隙数量不断减少，孔隙尺寸也不断变小；样品组织为粒状贝氏体，由板条状M/A岛和多边形铁素体组成，随着烧结温度的升高，M/A岛逐渐增多并不断长大；随着烧结温度的升高，烧结试样的密度、硬度、拉伸强度和屈服强度均不断提高，这与烧结试样孔隙率减少和硬质M/A岛不断增多有关。当烧结温度继续升高到1225℃，样品出现过烧现象，样品内出现孔洞等缺陷，其力学性能下降。在烧结温度为1200℃时样品得到最优性能，其拉伸强度和延伸率分别可达1288 MPa和12.52%。

Effect of sintering temperature on the microstructures and properties of 30Cr powder metallurgy low alloy steel

30Cr powder metallurgy low alloy steel was prepared by gas atomization and hot-pressing sintering, and the effect of sintering temperature on the microstructures and mechanical properties of the obtained low alloys steel was studied and analyzed by scanning electron microscope (SEM), Rockwell hardness tester, and mechanical test machine at different sintering temperatures. The results show that, when the temperature increases in 1100~1200, the number of pores on the samp℃ le surface is decreased, the pore size is also getting smaller. The sample microstructures show the granular bainite, which are composed of sheet bar M/A island and polygon ferrite. With the increase of sintering temperature, M/A island gradually increases and grows, and the density, hardness, tensile strength, and yield strength of the sintered samples are continuously improved, which is related to the reduction of porosity in the sintered samples and the increase of hard M/A islands. However, as sintering temperature continues to rise to 1225, the sample℃ shows the oversinter phenomenon, the sample defects are emerged, such as holes, and the mechanical performance of sample appears degradation. When the sintering temperature is 1200, the℃ sample gets the optimal performance as the tensile strength and elongation of up to 1288 MPa and 12.52%, respectively.