Aiming at the risk during the operation of nuclear power plants nuclear level manual valve is easy to leak,need to replace the whole of the valve,the joint of nuclear grade valve 2 specifications were carried out automatic pulse TIG welding of butt welded specimens and the penetration,X ray inspection and nondestructive inspection etc.the tensile,bending,metallographic examination,chemical analysis of damage and intergranular corrosion test The test results show that 2.77 mm welding joint tensile value is 564 MPa and the average elongation is 39.25％ 8.7 mm,the welding joint tensile mean value is 612 MPa and the average elongation is 46.75％,2 kinds of wall thickness of welded joints have good mechanical properties;the bending test,2 kinds of wall thickness the welding joint face bend test and back bending test are not found in cracks,both joints have good bending performance;microstructure of 2.77 mm joints is mainly lath shaped ferrite and microstructure of 8.7 mm joints mainly in dendritic ferrite;chemical composition of weld metal in welded joints of 2 kinds of wall the thickness of the inspected shall meet the technical conditions required;for intergranular corrosion test by bending method,the two kinds of joints have no tendency of intergranular corrosion.%针对核电厂运行期间核一级手动截止阀唇边焊易发生泄露的风险,要求阀门需要进行整体更换,分别对核级阀门两种规格的接头开展自动脉冲TIG焊接工艺研究,并对焊后的试件进行渗透、X射线探伤等无损检验和拉伸、弯曲、金相、化学分析和晶间腐蚀等破坏性检验.试验结果表明,壁厚2.77 mm的焊接接头拉伸力平均值为564 MPa,断后伸长率平均值为39.25％;壁厚8.7 mm的焊接接头拉伸力平均值为612 MPa,断后伸长率平均值为46.75％,两种壁厚的焊接接头均具有良好的力学性能,面弯试验和背弯试验均未发现裂纹,弯曲性能良好;壁厚2.77 mm接头的金相组织主要是板条状铁素体,壁厚8.7 mm接头的金相组织主要以树枝状铁素体为主;两种壁厚的焊接接头中熔敷金属的化学成分经检验均满足技术条件的规定;采用弯曲法进行晶间腐蚀试验,经检验两种规格的接头均无晶间腐蚀倾向.
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