The Research On Microstructure And Properties Of High-Strength Low-Alloy Steel Deposited Metals

This paper developed Mo-Ti-Ni welding wires with gas shielded welding low-alloy and high strength steel, deposited metal of welding wires have tensile strength of more than 1000 MPa, and low yield ratio(0.76), the toughness can reach more than 30J. The welding wires are used to welding manufacturing of high strength buildings which are low yield ratio.The microstructure of weld metal and the morphology of fracture appearance was observed with OEM, SEM and TEM. The test results show that Ceq should be hold in rational rang, which can insure high strength and high toughness of deposited metal. It was effective to achieve acicular ferrite core nucleations by adding proper Ti element to the welding wires. With the increase of the carbon content from 0.049% to 0.068%,flake martensite exists,and it is the reason that deposited metals have low toughness. Besides,much oxides inclusions is another reason. The cause of low yield ratio of the two deposited metal was investigated. The test results show that the deposited metal was made up with ferrite martensite,and ferrite in soft phase,and has a larger volume fraction,martensite was distributed of dispersion in ferritic matrix,and yield ratio of deposited metal decreased.