利用扫描电子显微镜(scanning electron microscope,SEM)、光学显微镜(optical microscope,OM)、拉伸、蠕变、疲劳试验机等研究了一种新型镍基粉末高温合金FGH4113A(WZ-A3)在2种热处理状态下的显微组织和力学性能,为双性能热处理研究提供组织与力学性能依据.结果表明:FGH4113A合金在双性能热处理中,过固溶与亚固溶态组织与力学性能具有明显的双模特性;室温下,亚固溶态相比过固溶态屈服强度高10.6％,800 ℃下,过固溶态相比亚固溶态屈服强度高11.7％;与同样是亚固溶或过固溶的其它合金相比,FGH4113A的拉伸强度优于ME3合金,与LSHR合金相当;FGH4113A合金在750 ℃/450 MPa的蠕变变形以位错滑移机制主导,弥散分布的小尺寸硼化物有助于抗蠕变性能的提高,其抗蠕变性能全面超过ME3合金,与LSHR合金相当;过固溶态的粗晶组织在裂纹扩展中具有更长的滑移带,在循环载荷中具有较低的累积损伤,抗裂纹扩展能力优于亚固溶态;过固溶态的裂纹扩展断口呈现穿晶断裂特征,亚固溶态由于细晶粒边界的一次γ'的存在降低了晶界的抗裂纹扩展能力,断口较粗糙,呈现沿晶-穿晶混合断裂特征.
Dual Microstructure and Mechanical Properties of FGH4113A Nicked-Based Superalloy
The microstructure and mechanical properties of a novel nickel-based powder superalloy FGH4113A under two heat treatment conditions were studied by scanning electron microscope(SEM),optical microscope(OM),tensile,creep and fatigue testing,providing the basis for the research of dual microstructure heat treatment(DMHT).The results show that the supersolvus and subsolvus microstructure and mechanical properties have obvious dual-mode.At room temperature,the yield strength of subsolvus sample is 10.6％higher than that of supersolvus sample,and at 800 ℃,the yield strength of supersolvus samples is 11.7％higher correspondingly.The tensile strength of FGH4113A is better than that of ME3 and equivalent to that of LSHR.The creep deformation of FGH4113A alloy at 750 ℃/450 MPa is dominated by the dislocation slip mechanism,and the dispersed small-sized borides are conducive to the creep performance improvement.FGH4113A has excellent creep properties,which is better than ME3 and equivalent to LSHR.The coarse-grained structure in the supersolvus sample has a longer slip band in crack propagation,resulting in lower cumulative damage under cyclic loading,and the crack growth resistance is better than that of subsolvus sample.The crack propagation fracture of the supersolvus sample is characterized by transgranular fracture.The existence of primary γ'on the fine grain boundary reduces the crack growth resistance,and the fracture is rough,showing mixed fracture characteristics of intergranular and transgranular.
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