Effect of heat treatment on microstructure and properties of TP304H/R102 dissimilar steel welded joints

In order to improve the high-temperature performance of ferrite-austenite dissimilar steel welded joints in the high-temperature section of the heating surface pipe system of power plant boilers,and improve the service life of the joint,a special heat treatment system and aging treatment conditions were formulated. Through mechanical properties test,high temperature creep rupture strength test,optical metallographic microstructure observation and other methods,the mechanical properties at room temperature,microstructures under different aging conditions,hardness distribution and carbon migration of TP304 H/R102 dissimilar steel joints in welded state and different heat treatment regimes were analyzed. The results showed that under the selected filler material and welding process,proper heat treatment process played a positive role in eliminating the hardening tendency of TP304 H/R102 dissimilar steel joints,improving the microstructure stability of low alloy heat-resistant steel and reducing carbon migration and diffusion（ from low alloy steel side to weld metal） and carbides accumulation,so as to ensure the high temperature creep rupture strength and improve service condition of joints.