.400 Mpa, The Level Of Low Alloy High Strength Steel Welding Consumables And Properties,

The designing principle of chemical compositions of high toughness submerged arc welding wires of 400MPa with Mn-Ni-Cr-Mo-Ti-B-Ce and Mn-Mo-Ti-B-Ce-Zr alloy system is introduced. Submerged arc welding with the test welding wire matching sintered flux was carried out to get the deposited metal. Experiment results indicate that matching the two kinds of flux the developed welding wire can produce deposited metals of good mechanical properties. Matching with flux of higher basicity the deposited metal have better mechanical properties (Rm>500MPa;ReL>600MPa;Akv J(-20℃)>150J). Microstructure of the deposited metals is composed of acicular ferrite and a little proeutectoid ferrite.Microstructure and property of X60 pipeline steel welding heat affected zone(HAZ) was investigated. The results indicated that the microstructure is coarsening and the toughness is worsening when the peak temperature enhances and t8/5 increases. The initial austenitic grain size and island microstructure(martensite> M-A constituent, carbonide) are the primary reason which affected the fracture impact toughness. Decreasing the percentage of carbon is benefit to reduce island microstructure and enhance toughness. Hardness distribution in welding HAZ indicated that softening zone exist in welding HAZ and the softening zone became wider with the increasing of heat input, So X60 pipeline steel was fit to low heat input welding(<30kJ/cm).Microstructure of 400Mpa ultrafine grain steels are ferrite and pearlite after austenize anneal and the grains became bigger apparently. Welding joints tension sample all fractured in the base metal when heat input ranged between 6kJ/cm and 16kJ/cm. The joints cold bend experiment indicated the welding joints have a good plastic property. The toughness of fusion line and HAZ of annealing simple was higher than non-annealing simple. Under the experiment's welding condition, WCX355 ultrafine grained steels didn't distinctly embrittle in CGHAZ and didn't soften in tempering zone either. The microstructure of weld seam columnar grain are composed of proeutectoid ferrite , FSA, massive ferrite and acicular ferrite. The microstucture of CGHAZ are composed of intergranular ferrite , FSA, bainite and a little acicular ferrite The microstructure of fine grain zone are composed of fine ferrite and pearlite.