基于材料力学性能的最低设计金属温度曲线分析

铁素体钢在低温条件下存在明显的韧脆转变现象。为防止脆断事故的发生,需要确定铁素体钢制压力容器的最低使用温度。针对ASME中的A^D四条冲击豁免曲线,对应地选取了4种材料,基于材料实际的屈服强度和参考温度,按照ASME中豁免曲线的计算方法,计算得到4种材料的最低设计金属温度曲线,并与对应的A^D曲线对比,定量地分析ASME中豁免曲线的保守性。结果表明,ASME中的豁免曲线相对于材料自身的最低设计金属温度曲线保守性较大;韧性相近的材料被划分到不同的豁免曲线,使得韧性富裕量差异较大,对于某些材料,其断裂韧性被低估。

Analysis of Minimum Design Metal Temperature Curve Based on Mechanical Properties of Material

There is an obvious phenomenon of ductile-to-brittle transition for ferritic steel at low temperature.In order to prevent the occurrence of brittle failure,it is necessary to determine the minimum design metal temperature of pressure vessel made from ferritic steel.The minimum design metal temperature curves of four steels corresponding to four impact exemption curves were acquired,and based on the actual yield strength and reference temperature of material and according to the calculation method in ASME,the minimum design metal temperature curves of four steels were obtained and compared with A^D impact exemption curves,respectively,in order to analyze the conservatism in impact exemption curve in ASME quantitatively.The results show that the impact exemption curves in ASME have relatively big conservatism with respect to the minimum design metal temperature derived based on the yield strength and reference temperature of material.The materials with same toughness were assigned to different impact exemption curves,which would lead to big difference in toughness surplus.The fracture toughness might be underestimated for some steels.