Microstructure and Mechanical Properties of Automatic Tungsten Inert Gas Welding Joint of 1Cr18Ni9Ti Stainless Steel
In order to improve welding efficiency and quality,automatic tungsten inert gas welding was used to conduct transverse welding tests on 1Cr18Ni9Ti pipelines used in natural gas stations.The microstructure of the welded joints was observed using optical microscopy(OM),scanning electron microscopy(SEM),and backscattered electron diffraction(EBSD),and mechanical properties such as tensile,bending,hardness,and impact were measured.The results show that the root weld of the joint is mainly composed of equiaxed austenite,while the filling cover weld is mainly composed of columnar austenite.The proportion of grain boundaries greater than 15 ° in the weld is 67.816%,and the orientation difference of grain boundaries is mostly between 40° and 45°.The tensile strength of the welded joints is higher than 710 MPa,and there are no cracks in both the transverse side bend and transverse face bend specimens.The impact energy of both the weld and HAZ is higher than 100 J,and the hardness is lower than 190HV10.Pitting test results indicate that it is not suitable for long term use in high chloride ion environments.The 1Cr18Ni9Ti pipeline used in the natural gas station can be welded at horizontal position 2G by automatic tungsten inert gas welding.The mechanical properties of the welded joints meet relevant standards and production requirements.
1Cr18Ni9Ti austenitic stainless steelautomatic tungsten inert gas weldingmicrostructuremechanical properties
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