A Study On Chemical Method Of Grain Refinement Of Inconel601H Nickel Based Alloy Weld

Inconel601H nickel based alloy has high mechanical properties and good oxidation resistance at high temperatures, also has excellent corrosion resistance for many corrosive medium. So it was extensively used in metallurgy, heat treatment,chemical, environmental protection and other fields. However, the thermal conductivity of Inconel601 H nickel based alloy was very bad, and welding joint stay at high temperature for a long time. As result, its grain of weld was very coarse. The weld coarse grains directly affect the mechanical properties of welded joints. This subject adopted the method that added refiner to the molten pool during welding, and the effect of grain refinement Inconel601 H nickel-based alloy welds was studied. TiC,ZrC and VC powder were selected as grain refiner. The grain refiner were transited to weld of Inconel601 H nickel-based alloy by using TIG welding. At the same time,the technology of the process of adding refining was studied. Then using optical light microscopy, SEM and EDS test equipment to observed and analyzed Inconel601 H nickel-based alloys weld and effects of refining. And researched the refiner impact on Inconel601 H weld microstructure. The mechanism for refiners Inconel601 H weld grain refinement was explored.The main conclusions were shown as following:(1)In the process of TIG welding of Inconel601 H nickel-based alloy, TiC, Zr C and VC can stable existence in the molten of weld pool. They have basic conditions of acting as heterogeneous nucleation substrate in the crystallization of liquid metal of weld.(2)Relying on their own weld pool convection refiner powder failed to effectively dispersed in the weld pool. Through the improvement of refiner addition process, made the refiner powder effectively dispersed in the weld pool. Welding defects were not observed in the weld joints of adding grain refiner.(3)When TiC, ZrC and VC evenly distributed in the weld, made the heat-affected zone of the welded joint narrowing, and the weld microstructure refinement, grains became smaller.(4)Different grain refiner on the grain refinement of Inconel601 H weld joints in different capacities, refining capacity of weak by the strong order of VC, TiC and ZrC.(5)The addition of grain refiner produced smaller grain structures in the melt pools, the reasons are as follows: Firstly,refiner has the effect of micro chill on the organization, increased the nucleation undercooling. Secondly, refinement of the surface is uneven, the nucleation of molten pool could be attached to the refinement of concave nucleation, reduce the nucleationenergy, promote nucleation. Thirdly, the generation of more sites for heterogeneous nucleation by the introduction of the grain refiner mixture into melt pools. Finally, the distribution in the grain boundary of grain refiner also plays a role in hinder the grain boundary migration. Based on the results, the grain refiner additions help to realize a grain refinement in the welds. Not only the size of the welds grains can be greatly reduced but the grain shape in the weld can also be changed from columnar to equiaxed grains.