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通过SEM、室温拉伸试验分析了20CrNi2Mo钢经900~1200℃淬火+200℃回火后的显微组织及力学性能。结果表明:随淬火温度的升高,20CrNi2Mo钢原奥氏体晶粒尺寸增加,强度和硬度降低,塑性有所增加。不同淬火温度下,马氏体板条间均会形成一层很薄的残留奥氏体薄膜,而且随淬火温度的提高,薄膜的分岔和弥散分布特征更加明显。拉伸断裂方式为韧性断裂,且放射区韧窝尺寸随淬火温度升高而增大。
The microstructure and mechanical properties of 20CrNi2Mo steel after quenching at 900 ~ 1200 ℃ and tempering at 200 ℃ were analyzed by SEM and tensile test at room temperature. The results show that as the quenching temperature increases, the original austenite grain size of 20CrNi2Mo steel increases, the strength and hardness decrease, and the plasticity increases. Different quenching temperature, martensite lath will form a thin layer of residual austenite film, and with the quenching temperature increases, the film bifurcation and dispersion characteristics more pronounced. Tensile fracture mode is ductile fracture, and dimple size of radiation zone increases with quenching temperature.