K17合金热等静压滞后热处理使塑性下降原因的探讨

A STUDY ON REDUCTION OF DUCTILITY OF K17 CAST NICKL SUPERALLOY AFTER POST-HIP HEAT TREATMENT

K17合金在热等静压后进行再热处理,能提高合金的高温持久与抗拉性能,但其塑性明显下降。本文针对此问题作了专门的分析与研究。对铸态、热等静压态及不同热处理制度下高温拉伸试样的金相与断口分析表明,合金塑性的好坏主要取决于晶界处阻挡裂纹扩展的颗粒的大小与数量。在Y+Y′共晶尾部出现的大批微裂纹也加速了高温沿晶的断裂。

The reduction of ductility of K17 alloy after post hot-isostatic pressing(HIP) heat treatment, which increases the high temperature rupture and the tensile properties of the alloy, was investigated in this paper. The fracture and metallographic analyses of specime failed after tension at high temperature under conditions e. g. as-cast, HIP'ed and post HIP heat treated with various regimes show that the ductility of the alloy depends mainly on the size and quantity of the particles which resist the extension of grain boundry cracks. The appearance of microcracks at the tail of 'γ+γ'eutectic' nodules will speed up the breaking along the grain boundaries.