Study On FCW For 2.25Cr1Mo Steels Containing Mechanical Property

With the rapid development of modern chemical industry, low-alloy heat-resistant steels were applied more and more widely in many tip industries, such as electric force, chemical industry, oil interests, nuclear power, aviation, etc. Better performances for the welding joint were required, such as higher high-temperature strength, high-temperature fatigue resistance and good plastic property, as well as better high-temperature stability and processing property. A great deal of heat-resistantant steel welding materials in the market were acidity welding materials, most of which can not meet the industrial requirements on mechanical property. Therefore it is important to develope a welding material for low-alloy heat-resistant steels with higher mechanical property.The paper systematically studied and analyzed the low-alloy heat-resistant steel flux-cored wire and the performances of deposited metal. The results are as follows:(1) A new type low-alloy heat-resisted steel alkalinity flux cored wire R407Q of slag system-MgO-BaF2-TiO2 was developed. By using one-factor design method, the influence of different compositions of R407Q flux-cored wire on processing property was analyzed. The optimum composition of flux core wire was determined by orthogonal expermental design method in order to achieve the best synthesis performances.(2) The chemical constitution, mechanical properties and welding operative performance of the deposited metal for R407Q wire were tested and were compared with domestic R407 wire. The results showed that R407Q FCW for low-alloy heat-resisted steels containing niobium reached advanced level of domestic wire.(3) Based on the ensurement of others mechanical properties of the deposited metal, the effect of post-heat treatment process on of the deposited metal for R407Q FCW was investigated. By using EDS, SEM and metallographs analysis, the effects of PWHT on the mirostructure, precipitate and impact fractures of deposited metal on impact ductily was studied. The optimum PWHT process for the welding joint of R407Q was achieved.