Study on microstructure and mechanical properties of welded joints of 15Cr1Mo1V steel pipeline in service
The microstructure,hardness,tensile strength,impact and failure position of the welded joint of 15Cr1Mo1V steel for high temperature reheat steam pipeline,which has been operated for about 130 000 hours in a power plant,were studied and analyzed.The results show that there are the polygonal ferrite and precipitates in each micro zones of the pipeline joint in service,and the microstructure appears the certain aging phenomenon.The hardness of each micro zones of the joint is obviously different,and the typical tempering effect of multi-layer and multi pass welding appears in the weld,and the hardness of the cover weld is generally high.The tensile and impact results of each micro zones of the welded joint show that the strengths of the weld at room temperature and elevated temperature are better than those of the base metal,but the plasticity and toughness are relatively poor,especially at elevated temperature,the plasticity and toughness of the weld decrease more.The tensile and impact fracture surfaces of the welded joint show that there are many dimples and deep dimples in the fracture surface of the base met-al.However,due to the precipitation of the second phase in the weld,although the tensile strength is im-proved,its plasticity and toughness significantly declined.
15Cr1Mo1V steelhigh temperature reheat steam pipelinewelded jointmicrostructuremechanical property
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