热等静压对激光选区熔化增材制造GH3230高温合金微裂纹与组织的影响

Effect of Hot Isostatic Pressing on Micro-Cracks and Microstructure of GH3230 Superalloy Fabricated by Selective Laser Melting

为揭示GH3230高温合金的激光选区熔化增材成形性,研究了热等静压对激光选区熔化增材制造GH3230高温合金微裂纹与组织及拉伸性能的影响。结果表明,激光选区熔化增材制造GH3230高温合金沉积态存在凝固微裂纹,该裂纹在XOY截面呈现龟裂特征,在ZOY截面呈现线状;热等静压之后,激光选区熔化增材制造GH3230高温合金的一部分微裂纹可以消除,另一部分较长的微裂纹难以消除。激光选区熔化增材制造GH3230高温合金沉积态组织基本为片状固溶体组织,在晶界附近存在少量析出碳化物;热等静压之后,在晶界附近析出大量的MoWCr碳化物,而晶内析出MoWCr碳化物数量多且尺寸较小。凝固微裂纹导致激光选区熔化增材制造GH3230高温合金沉积态XY方向抗拉强度及延伸率降低,而热等静压能减小大尺寸微裂纹,消除小尺寸微裂纹及气孔,可大幅提高XY方向的抗拉强度和延伸率。

It was investigated that micro-cracks and microstructure characteristics of GH3230 superalloy fabricated by selective laser melting(SLM)before and after hot isostatic pressing(HIP)in order to reveal the SLM additive formability of GH3230 superalloy.The results show that there are many solidification micro-cracks in the SLM as-deposited GH3230 superalloy,and the micro-crack distribution is netlike along the XOY section and is threadlike along the ZOY section.Most of the solidification micro-cracks can be eliminated by HIP,and some longer micro-cracks are difficult to eliminate.There is elemental segregation phenomenon in as-deposited GH3230 superalloy fabricated by SLM,and exist a small amount of carbides along the boundary.After HIP,a large number of secondary carbides of MoWCr alloying elements are precipitated and the carbides along the boundary are larger than the intracrystalline precipitated ones.Micro-cracks easily reduce the XY direction tensile strength and elongation of as-deposited GH3230 fabricated by SLM and the XY direction tensile strength and elongation is greatly improved by HIP,and the effect mechanism was made a preliminary analysis.