针对B50A224钢系列温度冲击试验数据,首先采用不同的方法进行拟合,通过比较得出双曲正切函数拟合得到的曲线更符合冲击功及脆性断面率随温度变化的规律,且能降低因冲击试样不均匀对由拟合曲线求得的韧脆转变温度的影响.然后分析了材料显微组织对韧脆转变温度的影响,找出了造成B50A224钢冲击试验出现异常数据的原因.最后通过改进热处理工艺,降低了该钢的韧脆转变温度,提高了其在低温下的抗冲击能力.

First the impact test data of B50A224 steel at a series of temperatures were fitted by different methods,and by comparing it was found that the curves fitted by hyperbolic tangent function method were more in accordance with the changing rules of impact absorbed energy and percentage of brittle fracture surface with the temperature.At the same time,hyperbolic tangent function fitting method could reduce the influence of material nonuniformity on the ductile-brittle transition temperature obtained from the fitting curves.Then the effect of microstructure on the ductile-brittle transition temperature was studied,and reasons for the abnormal data were found out.At last,by improving the heat treatment process,ductile-brittle transition temperature of the steel was reduced and the low temperature impact resistance was improved.