搅动法细晶铸造K492M合金的显微组织和拉伸性能

Microstructure and Tensile Properties of K492 Alloy Produced by Mould Agitation

采用扫描电子显微镜(SEM)、电子探针(EPMA)和拉伸性能测试等手段,研究了搅动法细晶铸造K492M合金的显微组织和拉伸性能。显微组织观察表明,铸态组织主要包括γ基体、γ′相、碳化物及γ/γ′共晶;热处理后,合金枝晶干和枝晶间处的γ′相由大、小两种尺寸组成,共晶组织未完全溶于基体;碳化物沿晶界析出,呈链状分布。合金在750℃的抗拉强度和伸长率分别为(1157±12)MPa和(9.1±2)%。抗拉断口SEM观察显示,断裂机理主要为韧窝断裂。

The microstructure and tensile properties of K492 alloy produced by the mould agitation have been investigated by means of SEM (Scanning Electron Microscope), EPMA (Electrical Probe Metal Analysis) and mechanical test in the present study. The microstructure observation reveals that the as-cast microstructure with refined grains is composed of γ matrix,γ′ phase, MC carbide and γ/γ′ eutectic;after solid solution heat treatment,γ' precipitates with two obviously distinct size existed in the dendrite core and interdendritic region. Fine carbides precipitate along the grain boundary and γ/γ′ eutectic phase incompletely dissolve in matrix. Tensile properties at 750 ℃ were measured, and results obtained show that tensile strength and elongation are (1 157±12)MPa and(9.1±2)%, respectively. Furthermore, tensile fractured surfaces examined under SEM show that the deformation mechanism at 750 ℃ is dimple fracture.