Effect of hot isostatic pressing on microstructure of K439B superalloy

doi:10.13251/j.issn.0254-6051.2020.11.033

Abstract

Abstract: K439B superalloy was hot isostatic pressed (HIP) under 1165 ℃/150 MPa for 4 h, then the microstructure of as-cast and hot isostatic pressed K439B alloy was investigated comparatively by using OM and SEM. The results show that the as-cast K439B alloy has microporosity of 0.25%, which is reduced down to only 0.013% after HIP. Compared with the as-cast microstructure, after HIP both the content and the size of γ/γ′ eutectic decrease, and all the elements are distributed more evenly, with their solidification segregation coefficients being closer to 1. The size and volume fraction of γ′ precipitates in the dendritic arms of as-cast K439B alloy are 116.9 nm and 17.8% respectively, and that in interdendritic region are 244.4 nm and 24.9%. After HIP, the size and volume fraction of γ′ precipitates in the dendritic arms are 148.0 nm and 17.5% respectively, and that in the interdendritic region are 159.1 nm and 22.8%. The hot isostatic pressing makes that the size, volume fraction and morphology of γ′ precipitates in the dendritic arms in the alloy and that in the interdendritic region become more similar to each other, and the γ′ precipitates distribute more uniformly.

Key words: K439B superalloy, hot isostatic pressing, microstructure, microporosity, γ/γ′ eutectic

CLC Number:

TG132.3⁺2

Zhang Mingjun, Zhang Leilei, Hu Yingtao, Tang Xin, Yang Qing. Effect of hot isostatic pressing on microstructure of K439B superalloy[J]. Heat Treatment of Metals, 2020, 45(11): 177-181.

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