循环正火处理对9Cr3W3Co钢组织及冲击韧性的影响

Effect of cyclic normalization on microstructure and impact toughness of 9Cr3W3Co steel

采用光学显微镜、扫描电镜和冲击试验等研究了9Cr3W3Co钢经1075℃多次循环正火处理后的显微组织和冲击韧性。结果表明:多次循环正火处理可显著细化9Cr3W3Co钢的晶粒尺寸,提高了合金的冲击韧性。晶粒尺寸由1次正火处理的38.05μm,降为5次循环正火处理的25.73μm;冲击功由1次正火处理的51.69 J,增加为4次循环正火处理的110.75 J,5次循环正火处理的95.60 J。循环正火处理后试样观察到大量富W和Fe元素的Laves相,且Laves相尺寸随正火循环次数的增加而增大。冲击功随正火循环次数的增加先增大后减小,与合金奥氏体的晶粒尺寸和析出Laves相的尺寸相关。

Microstructure and impact toughness of 9Cr3W3Co steel after cyclic normalization at 1075 ℃ for different times were studied by means of optical microscope,scanning electron microscopy and impact test. The results show that many times cyclic normalization treatment can remarkably refine the grain size of the 9Cr3W3Co steel and improve the impact toughness of the steel. The grain size decreases from 38. 05 μm with one time cyclic normalization treatment to 25. 73 μm with five times cyclic normalization treatment,and the impact toughness increases from 51. 69 J with one time cyclic normalization treatment to 110. 75 J with four cyclic normalization treatment,to 95. 60 J with five times cyclic normalization treatment. After cyclic normalization treatment,a large number of Laves phases with rich W and Fe elements are observed,and the size of the Laves phase increases with the increasing of cyclic normalization times. The impact toughness of the 9Cr3W3Co steel increases first and then decreases with the increasing of cyclic normalization times,and is related to the grain size of the austenite and the size of the precipitated Laves phase.