热处理对选区激光熔化GH3230高温合金显微组织及高温拉伸力学性能的影响

Effect of Heat Treatment on Microstructure and High Temperature Tensile Mechanical Properties of Selective-Laser-Melted GH3230 Superalloy

为有效提高GH3230高温合金的综合高温力学性能,本研究利用选区激光熔化技术成形了GH3230试样,按照设计的热处理制度做了固溶处理。分析了固溶处理前后合金的显微组织结构,测试了合金的高温拉伸力学性能,研究了析出碳化物的形态和分布对高温拉伸力学性能的影响规律,探讨了高温拉伸断裂机制。结果表明:选区激光熔化GH3230合金显微组织由生长方向与材料堆积方向一致的单一γ固溶体柱状晶构成。固溶处理后,沿γ固溶体柱状晶晶界析出了呈链状分布的MC型碳化物颗粒,在柱状晶内部析出了弥散分布的MC型超细碳化物颗粒,柱状晶变粗,晶粒取向差异减小,出现向等轴晶转变的趋势;高温拉伸力学性能各向异性程度减弱,由于显微组织仍为具有定向凝固特征的柱状晶组织,不同方向的高温拉伸力学性能仍存在差异;纵向及横向高温拉伸断裂机制均为沿晶韧性断裂。

In order to effectively improve the comprehensive high temperature mechanical prop erties of GH3230 superalloy, the GH3230sample was formed by selective laser melting technology, and the solid solution treatment was carried out according to the designed heat treatment system. The microstructure of the alloy before and after solution treatment was analyzed, the high temperature tensile mechanical properties of the alloy were tested, the influence of the morphology and distribution of precipitated carbides on the high temperature tensile mechanical properties was studied, and the mechanism of high temperature tensile fracture was discussed. The results show that the microstructure of GH3230 superalloy by selective laser melting is composed of single γ solid solution columnar crystals with the same growth direction as the material stacking direction. After solution treatment, MC type fine carbide particles with chain distribution are precipitated along the grain boundary of γ solid solution columnar grains, and MC type ultrafine carbide particles with dispersion distribution are precipitated inside the columnar grains. The columnar grains become coarser, and the grain orientation difference decreases, showing a trend of equiaxed grain transformation. The degree of anisotropy of high temperature tensile mechanical properties is weakened. Because the microstructure is still columnar grain with directional solidification characteristics, the mechanical properties of high temperature tensile in different directions are still different. Both longitudinal and transverse high temperature tensile fracture mechanisms are intergranular ductile fracture.