The effects of Ce, Ti, Nb and C on the microstructures and mechanical properties of Ni Fe weld metal and the mechanism of their strengthening are discussed. Ce has the effect on graphite morphology and weld metal with spheroidal graphite has higher mechanical properties. The proper contents of Ti and Nb obviously increase the tensile strength of Ni Fe weld metal, which is mainly attributed to the austenite grain refining and second phase (TiC and NbC) strengthening. The excess C in weld metal results in increasing the quantity of carbide and graphite precipitating along the austenite grain boundary and decreasing the mechanical properties of Ni Fe weld metal.
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