12Cr1MoVG焊接接头高温短时拉伸及可靠性评价

分别对焊态和焊后热处理(PWHT)的12Cr1MoVG钢焊接接头进行300~600℃高温短时拉伸试验,根据该试验结果可以推算出接头的持久强度。结果表明,随测试温度的升高,两种接头的高温短时拉伸强度降低,伸长率升高。断口形貌分析表明接头的断裂机制由剪切断逐渐过渡到正断。焊态接头的高温短时拉伸强度均高于PWHT态接头。510℃时,焊态及PWHT态接头的持久强度下限(σ105783)分别为61 MPa和86 MPa,均大于某电站锅炉的额定蒸气压力(30.35 MPa)。PWHT态12Cr1MoVG钢接头具有较高的持久强度,因而具有更高的服役可靠性。

High-temperature short-term tensile test and reliability assessment of 12Cr1MoVG steel welded joints

The welded joints of 12 Cr1 MoVG steel with and without post-weld heat treatment(PWHT)were subjected to a high-temperature short-term tensile test at the temperature of 300-600℃,and the creep rupture strength of the joints was calculated according to the test result.The results show that,with the increase of the test temperature,the high-temperature short-term tensile strength of the two joints decreases and the elongation increases.The fracture morphology analysis shows that the fracture mechanism of the joints is gradually transformation from the shear to the normal modes.The high-temperature short-term tensile strength of the as-welded joint is higher than that of the joint after heat treatment.The lower limit of the creep rupture strength of the welded joints with and without PWHT at 510℃is 86 MPa and 61 MPa,respectively,which is higher than the rated steam pressure of a certain power station boiler(30.35 MPa).The welded joint of the 12 Cr1 MoVG steel has higher creep rupture strength after heat treatment,so it has higher long-term service reliability.