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对经焊接、焊后热处理的P91无缝管接头分别进行1~4次回火处理,利用化学成分分析、常温和高温拉伸试验、显微硬度及金相检验等,研究了回火次数对焊接区域力学性能及显微组织的影响,并探索焊接区域在不同热处理次数下显微硬度与常温及高温力学性能的对应关系。结果表明,P91管焊接区域在多次回火热处理后,其显微组织为回火索氏体,但析出碳化物有增多的趋势;参比样的显微硬度与室温抗拉强度相关系数最大,即3.69,而回火一次后,试样的显微硬度与高温抗拉强度间相关系数达到最大值,即1.48。
The welded and postweld P91 seamless pipe joints were tempered 1 to 4 times respectively. The chemical composition analysis, tensile test at room temperature and elevated temperature, microhardness and metallographic examination were used to study the effect of tempering times on the welding The mechanical properties of the region and the influence of the microstructure. The corresponding relationship between the microhardness and the mechanical properties at room temperature and high temperature of the welding area under different heat treatment times is also explored. The results show that the microstructure of P91 pipe is tempered sorbite after several times of tempering heat treatment, but the precipitated carbides tend to increase. The correlation coefficient between the microhardness and the tensile strength at room temperature is the highest, Namely 3.69, and after tempering once, the correlation coefficient between the microhardness and high temperature tensile strength of the sample reaches the maximum value, namely 1.48.