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ISSN : 1225-0562(Print)
ISSN : 2287-7258(Online)
Korean Journal of Materials Research Vol.30 No.9 pp.465-473
DOI : https://doi.org/10.3740/MRSK.2020.30.9.465

Effect of Post-clad Heat Treatment on Microstructures and Mechanical Properties of Cu–NiCrBSi Dissimilar Laser Clads

Kyeong-Min Kim1,Ye-Seon Jeong1,Ahjin Sim2,Wonah Park3,Changkyoo Park4,Eun-Joon Chun1†
1Department of Nano Materials Science and Engineering, Kyungnam University, Changwon 51767, Republic of Korea
2Advanced Machine Tool Technology Team, Doosan Machine Tools, Seoul, 04637, Republic of Korea
3Department of Mechanical and Automotive Engineering, Kyungsung University, Busan 48434, Republic of Korea
4Laser and Electron Beam Application Department, Korea Institute of Machinery and Materials, Daejeon 34103, Republic of Korea
Corresponding author E-Mail : ejchun@kyungnam.ac.kr (E.-J. Chun, Kyungnam Univ.)

Abstract

For surface hardening of a continuous casting mold component, a fundamental metallurgical investigation on dissimilar laser clads (Cu–NiCrBSi) is performed. In particular, variation behavior of microstructures and mechanical properties (hardness and wear resistance) of dissimilar clads during long-term service is clarified by performing high-temperature postclad heat treatment (temperature range: 500 ~ 1,000 ℃ and isothermal holding time: 20 ~ 500 min). The microstructures of clad metals (as-clads) consist of fine dendrite morphologies and severe microsegregations of the alloying elements (Cr and Si); substrate material (Cu) is clearly confirmed. During the post-clad heat treatment, the microsegregations are totally homogenized, and secondary phases (Cr-based borides and carbides) precipitated during the short-term heat treatment are also almost dissolved, especially at the heat treatment conditions of 950 ℃ for 500 min. Owing to these microstructural homogenization behaviors, an opposite tendency of the surface mechanical properties can be confirmed. In other words, the wear resistance (wear rate) improves from 4.1 × 10−2 mm3/Nm (as-clad condition) to 1.4 × 10-2 mm3/Nm (heat-treated at 950 ℃ for 500 min), whereas the hardness decreases from 453 HV (as-clad condition) to 142 HV (heat-treated at 950 ℃ for 500 min).

후열처리에 따른 Cu–NiCrBSi 이종 레이저 클래드부의 미세조직 및 기계적 성질 변화

김경민1,정예선1,심아진2,박원아3,박창규4,천은준1†
1경남대학교 나노신소재공학과, 2두산공작기계 선행기술팀 3경성대학교 기계자동차공학전공, 4한국기계연구원 광응용기계연구실

초록

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