Effect Of Carbon On Microstructure And Property Of GH3536 Alloy Formed By Laser Melting And Deposition

GH3536 alloy(Hastelloy X)is a solid solution strengthened nickel-based superalloy with high iron content.It has good high temperature resistance,oxidation corrosion resistance,creep fatigue resistance and thermal stability.It is mainly used in aero engine combustion chambers.Parts and other high temperature parts.In order to meet the demand for high thrust-to-weight ratio of aero-engines,high-temperature alloy parts are developing in the direction of lighter weight and more complex structure.Traditional processing and preparation techniques are difficult to meet the demand.Additive manufacturing technology is a new type of manufacturing technology in recent years,which can break through the limitations of traditional technology for preparing porous and hollow structures,and has great advantages in preparing parts with complex structures.Trace element C plays a vital role in the additive manufacturing process of GH3536 alloy.Therefore,in this paper,four kinds of GH3536alloys with different C content were prepared by laser melting deposition forming process,and the microstructure and mechanical behaviors of tensile and persistence of GH3536 alloys with different C content were analyzed to explore the mechanism of C.In addition,the alloy was subjected to heat treatment experiments at three temperatures to analyze the effects of different heat treatment regimes on the alloy's microstructure,element segregation and mechanical properties.The main results are as follows:(1)The composition phase of GH3536 alloy formed by laser melting and deposition was mainly?-(Fe-Ni)phase,there was a clear molten pool boundary inside the sample,and the lower part of the sample was composed of epitaxially grown grains of different sizes;the middle part;It was a columnar crystal penetrating the molten pool.When the carbon content was low,there were sporadic granular carbides at the grain boundaries;as the carbon content increased,the granular carbides in the grains gradually increased,and the shape becomes chain-like and strip-like.(2)After the double aging treatment,compared with the deposited structure,there were more granular carbides in the alloy grains,and the carbides were precipitated along the grain boundary in a lamellar shape,and the boundary of the molten pool inside the sample becomed shallow;solid solution after treatment(980°C/1h)and double aging treatment(720°C/8h+620°C/8h),needle-like Laves phase(Cr₂Mo)precipitated near the grain boundary,the boundary of the molten pool inside the sample disappeared,and the grain size increased large;increased the solution treatment temperature(1100?),the needle-like phase near the grain boundary disappeared,and the granular carbide containing Cr,Mo and W dispersed and precipitated inside the grain.(3)The vickers hardness of the lower part of the GH3536 alloy sample formed by laser melting and deposition was higher than that of the upper/middle part.As the carbon content increased,the tensile strength of the GH3536 alloy sample increased first and then decreased.After the sample has undergone high-temperature solution treatment and double aging treatment,the tensile strength and elongation increased.The endurance life of the GH3536 alloy sample formed by laser melting and deposition also has shown a trend of first rising and then decreasing with the increase of carbon content;the property was the best when the carbon content is 0.08%,and the stress rupture life of alloy was273.4h at the condition of 500?/85MPa;and the stress rupture life of alloy was 19.6h at the condition of 815?/110MPa;the best stress rupture property of alloy was after high temperature solution treatment and double aging treatment,and the stress rupture life of alloy was 315.4h at the condition of 500?/85MPa;and the stress rupture life of alloy was 127.5h at the condition of 815?/110MPa.