Study Of Weldability And Impact Test For Butt Welds Of Domestic F92, Heat Resistant Steel For Boiler

F92 heat resistant steel has good high-temperature strength, fume resistance, corrosion resistance ability and high value price ratio. F92 steel can be used in the supercritical boiler as nozzles and end covers of headers, which service temperature is about 625℃. The weldability grading of homemade F92 steel can realize the technique performance of it, make technique foundation of F92 steel domestically produced, provide technical base of homemade F92 steel used in the 300MW and 600MW boiler super-heater and made suitable welding and heat-treatment techniques. It can promote the capacity volume and efficiency of thermal power electric generating set, solve the electric power shortage state of our country and promote the development of national economy.In this paper, the F92 steel and the CGHAZ of the welding joint are studied. The implant test, Y-slit type cracking test, hardness test of the welding joint, SEM and the F92 steel cracking boring and expansion test were used to study the F92 steel tube cold crack sensibility. The welding thermal simulation, metallographical test, Charpy-type test, hardness test and TEM microstructure analysis were used to study the effect of different technique parameters on the F92 steel multi-pass welding joint CGHAZ toughness.SA182-F92 steel welding process test results show that the steel has a tendency to crack cold, the China-made F92 steel, compared to imported F92 steel, the cracks are more sensitive to cold. Through the test rod bolt fracture SEM analysis showed that fracture Bolt test bar with warm temperatures and significant change. Welded joints of the impact test showed that heat treatment parameters of the HAZ toughness values have significant impact on domestic steel F92 PWHT the best parameter for tempering 21.49, corresponding to the norms of treatment for 770℃×4h for each Heat treatment parameters, and the heat affected zone of hardness and toughness is a negative correlation between the value of the relationship. Different thermal simulation cycle parameters of the regional fracture microstructure photos show that the heat affected zone for organizations with a significant feature of martensitic microstructure of the composition. Domestic F92 steel welding should adopt the multi-channel multi-layer welding, taking control of each layer of weld thickness is conducive to the former back-channels in a favorable role in tempering, and should control the temperature between layers of not more than 300℃.