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This paper developed a Mo-Ti-Ni -based high strength low alloy steel gas shielded welding wire, the wire deposited metal tensile strength exceeding 1000MPa, and has a low yield ratio (0.76), -20 ° C to achieve 30J impact toughness above . The wire can be used for low- yield ratio , there are strict requirements for welding high strength steel structures fabrication . In component analysis and mechanical testing , based on the use of optical microscopy (OM), SEM, TEM observation test on weld metal composition, microstructure and properties were studied , the results showed that: to ensure that the weld metal has sufficient strength , it is necessary to ensure adequate solid solution strengthening element content , and to ensure reasonable control of Ceq low temperature toughness of the weld metal ; in this alloy system , add the micro-alloying elements Ti -rich titanium composite oxide formation can be acicular the nucleation of ferrite core , thus grain refinement ; when deposited metal carbon content from 0.049% to 0.068% , the deposited metal appeared twinned martensite , which is lower weld metal toughness the main reason. In addition, gas shielded arc welding to join the stable oxidizing gas burning of alloying elements caused by the formation of oxide inclusions is low toughness incentives ; microstructure observation showed that : The deposited metal has bainite and martensite dual phase structure , bainite soft phase , and has a larger volume fraction of martensite distributed in the bainitic matrix , this duplex structure effectively reduces the weld metal yield ratio .
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