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pISSN : 1598-706X / eISSN : 2288-8381


(논문)연구논문

한국주조공학회지 (40권2호 16-24)

The Effect of Heat Treatment on the Microstructures and Mechanical Properties of Inconel 713C Alloy Vacuum Investment Castings

진공 정밀주조한 Inconel 713C 합금의 조직과 기계적 성질에 미치는 열처리의 영향

Byung-Ki Yoo*, Hak-Kyu Choi**, Heung-Il Park*** and Hae-Yong Jeong****,†

MCM Co.,Ltd., SH Consulting, Pukyoung Nat'l Univ,

DOI : http://dx.doi.org/10.7777/jkfs.2020.40.2.16

Abstract

The effect of a heat treatment on the microstructure and mechanical properties of Inconel 713C alloy vacuum investment castings were investigated. The microstructure of the as-cast state was observed, showing well-developed dendrite structures and distributed carbide particles and solidified massive precipitates in the grain or grain boundary during solidification, in this case the ′phase and MC particles. During a heat treatment, the  phase matrix was reinforced by solid solution elements, carbide particles from the film morphology precipitated along the grain boundary, and many micro-precipitates of second ′ phases 0.2 m~2 m in size were newly formed in the  phase matrix according to SEM-EDS analysis results. The tensile strength at a high temperature (850oC) decreased slightly becoming comparable with the room-temperature result, while the hardness value of the specimen after the vacuum heat treatment increased by approximately 19%, becoming similar to that of the as temperature result, while the hardness value of the specimen after the vacuum heat treatment increased by approximately 19%, becoming similar to that of the as-cast condition. However, the impact values at room temperature and low temperature (-196oC) were approximated; this alloy was mostly not affected by an impact at a low temperature. In the observations of the fracture surface morphologies of the specimens after the tensile tests, the fractures at room temperature were a mix of brittle and ductile fractures, and an intergranular fracture in the inter-dendrite structure and some dimples in the matrix were observed, whereas the fractures at high temperatures were ductile fractures, with many dimples arising due to precipitation. It was found that a reinforced matrix and precipitates of carbide and the  ′ phase due to the heat treatment had significant effects, contributing greatly to the excellent mechanical properties.

Keywords

: Inconel 713C, Microstructure, Tensile properties, Impact value, Precipitation, Carbide, Vacuum investment casting, Vacuum