热处理对焊接快速成形GH4169合金组织和性能的影响

Effects of Heat Treatment on Microstructure and Mechanical Properties of GH4169 Nickel-base Superalloy Prepared by Welding Rapid Forming

利用TIG焊接快速成形法制备了GH4169镍基高温合金多道多层块状试样,并对试样的组织和力学性能进行了分析。组织分析表明,沉积态试样组织宏观上呈现以基材为基底的外延连续生长的粗大柱状晶的特点,层与层间过渡不明显;无宏观冶金缺陷存在,仅存在少量弥散分布的细小气孔;试样在热处理过程中发生再结晶,且不同区域的再结晶晶粒尺寸和分布不一致,试样底部晶粒尺寸最小、分布更均匀,越靠近试样顶部枝晶越粗大。热处理前后试样的硬度沿沉积方向从下至上呈减小的趋势,热处理后硬度提高。热处理后试样抗拉强度有所提高,最高达到1 250 MPa,接近锻件标准,但是局部区域抗拉强度仍存在一定的差距。

GH4169nickel-based superalloy sample was prepared by TIG welding rapid forming.The microstructure and mechanical properties of the sample prepared were investigated.Microstructure analysis reveals that coarse columnar crystals are continuously grown from the substrate.The transition between the layers is not obvious,and absence of macro metallurgical defects can be observed.There exists only a few dispersed pores in the sample.Recrystallization occurs during heat treatment,and size distribution of the recrystallized grains are varied at different regions,where grain size at the bottom of the sample exhibits the smallest and uniform,while the dendrite size closer to the top of the sample becomes coarse.The hardness of the sample along the deposition direction shows a decreasing trend from the bottom to the top before and after heat treatment.Tensile tests indicate that the mechanical properties of heat treated samples at different regions are improved.The maximum tensile strength can reach up to 1 250 MPa,which is closer to the forged part standard,however,partial differences in ultimate tensile strength still exist.