正火温度对SA-516Gr.70钢板性能和组织的影响

Effect of Normalizing Temperature on Properties and Microstructures of SA-516Gr.70 Steel Plate

采用力学性能测试和显微组织分析方法,研究了不同正火温度对SA-516Gr.70钢板性能和组织的影响规律。结果表明,在保温时间为30 min时,随正火温度从880℃升高到940℃,钢板的强度不断下降,断后伸长率得到提升,冲击韧性有了较大改善,-20℃冲击吸收能量先增大后减小;钢中组织得到均匀化,带状组织逐渐被消除;但当正火温度达到940℃时,晶粒开始出现不同程度粗化,降低了钢板的冲击韧性和均匀性。钢板最佳正火温度为920℃。

The law of effect of different normalizing temperatures on the properties and microstructures of the SA-516Gr.70 steel plate was studied by using mechanical property testing and microstructure analysis method.The study results showed that at holding time of 30 minutes,as the normalizing temperature increased from 880℃to 940℃,the strength of the steel plate continuously decreased,while the elongation after fracture increased and the impact toughness improved significantly.Particularly,the impact absorption energy at-20℃increased at first and then decreased.In addition the microstructures in the steel got homogenized and the banded structures were gradually eliminated.However,when the normalizing temperature reached 940℃,the grains began to coarsen in different degrees,which reduced the impact toughness and uniformity of the steel plate.So it was concluded that the optimal normalizing temperature for steel plates was 920℃.