通过试验获得9Ni钢焊接接头、母材和焊缝在室温20℃和低温-158℃下的拉伸和断裂性能,对比分析了温度对性能的影响;建立了母材和焊缝的近似R6选择2失效评定曲线(FAC)以及9Ni钢焊接接头的FAC,并进行了对比。结果表明:低温下母材的拉伸和断裂性能以及接头和焊缝的拉伸性能均高于室温下,焊缝的断裂韧度几乎不随温度改变;不同温度下焊缝的屈服强度和断裂韧度均低于母材,焊缝是9Ni钢焊接接头的薄弱区域。由室温拉伸性能构建的近似选择2 FAC包络面积均略小于采用低温拉伸性能构建的FAC,故可用室温拉伸性能构建近似选择2 FAC对9Ni钢焊接接头进行安全评定;分段选取室温下母材和焊缝的近似选择2 FAC构建的焊接接头FAC能最保守地对低温9Ni钢含缺陷结构进行安全评定。

The tensile and fracture properties at 20℃ room temperature and -158℃ low temperature of 9Ni steel welded joint, base metal and weld were obtained by experiments, and the effects of temperature on the properties were compared and analyzed. Approximate R6 option 2 failure assessment curves (FAC) for the base metal and weld, as well as FAC for the 9Ni steel welded joint were established and compared. The results show that the tensile and fracture properties of the base metal and the tensile properties of the joint and weld at low temperature were higher than those at room temperature, but the fracture toughness of the weld hardly changed with temperature. The yield strength and fracture toughness of the weld at different temperatures were lower than those of the base metal, and the weld was a weak area of the 9Ni steel welded joint. The envelope area of the approximate option 2 FAC constructed with room temperature tensile properties was slightly smaller than that with low temperature tensile properties, so the approximate option 2 FAC constructed with room temperature tensile properties can be used for safety evaluation of 9Ni steel welded joints. The FAC of 9Ni steel welded joint constructed by segment selection of the approximate option 2 FACs of the base metal and weld at room temperature can be used for safety evaluation of 9Ni steel defect-containing structures at low temperatures in the most conservative way.