20SiMn2MoV合金结构钢的低温冲击性能

Impact Property of 20SiMn2MoV Steel at Low Temperature

针对石油钻采设备的服役条件，考察了20SiMn2MoV合金结构钢在-60℃-20℃内的冲击性能以及热处理工艺、毛坯尺寸等因素的影响。试验结果表明，20SiMn2MoV钢的冲击性能在试验温度范围内随温度降低而逐渐下降。在低温（略高于Ac3）淬火＋高温回火时，毛坯尺寸对冲击性能的温度依赖性有显著影响，毛坯尺寸越大，冲击性能随温度下降而降低的变化率越高。在高温淬火＋低温回火时，20SiMn2MoV钢表现出较低的冲击性能，但温度对冲击性能的影响相对较小。适当降低淬火温度，提高回火温度有利于改善20SiMn2MoV钢的冲击性能。冲击断口分析表明，断口上存在着团簇状的碳化物和氧化物颗粒及其脱落后而形成的孔洞，对于钢的冲击性能产生不利影响。

For the service conditions of petroleum devices at low temperature, the effects of the heat treatment processes and ingot sizes on the impact property of 20SiMn2MoV steel,under the range of -60℃- 20℃ were studied. The results show that the impact property of 20SiMn2MoV steel decreases gradually with the test temperature decreasing. Under the condition of low temperature quenching（ slightly higher than Ac3 ）and high temperature tempering,the ingot size has an evident effect on the temperature dependence of the impact property：the larger the ingot size, the more dramatically the impact property decreases of the steel with temperature decreasing. Under the condition of high temperature quenching and low temperature tempering, the impact property of the steel is low, however, the temperature influence is relatively weak. It is found that decreasing the quenching temperature and increasing the tempering temperature properly would be beneficial to improve the impact property of the steel. The fracture analysis shows that there exist clustered particles of carbides, oxides, and voids resulted from shedding of the compounds which would be harmful to the impact property.