소결 방법에 따른 WC-20wt%Co 초경합금의 인장 특성 및 피로 수명

• Published in: 대한금속·재료학회지, 60(3) Vol. 60; no. 3; pp. 227 - 236
• Main Authors: 류성현, Seong Hyeon Ryu, 조무근, Mu Geun Jo, 김경일, Kyung Il Kim, 노우람, Wooram Noh, 홍익제, Ik Je Hong, 이광희, Kwang Hee Lee, 김상섭, Sang Sub Kim, 조규섭, Gue Serb Cho
• Format: Journal Article
• Language: Korean
• Published: 대한금속재료학회 05.03.2022; 대한금속·재료학회
• Subjects: fatigue; microstructure; sintering method; tensile strength; WC-Co cemented carbide; 재료공학
• ISSN: 1738-8228; 2288-8241
• DOI: 10.3365/KJMM.2022.60.3.227

WC-Co cemented carbide has excellent mechanical properties and is widely used in many industrial applications including cold forging die and cutting tools. WC-Co cemented carbide is manufactured by liquid phase sintering (LPS), and a new sintering process for densification has been developed. In this study, cylindrical rod shaped tensile and fatigue specimens of WC-20wt%Co cemented carbide were fabricated using commercial sintering methods such as vacuum sintering (VS), low pressure sintering (LP), sinter HIP (S-HIP), and HIP after vacuum sintering(VS+HIP). The effect of the sintering methods on microstructure, tensile properties and fatigue life was investigated. The relative density and average size of the WC particles increased after additional HIP treatment. Also large abnormal WC particles were observed. In the tensile test, the deviation of tensile properties (maximum tensile strength, elongation) was minimized in the VS+HIP specimen due to densification. Based on the uniaxial tensile-compression fatigue test, the SN curve of WC- 20wt%Co cemented carbide was concluded to be logσ a = -0.11244logN f +3.66817. Furthermore, the increase in WC particle size in the HIP process caused the VS+HIP specimen to have a lower fatigue life than the VS specimen. However, when high pressure was applied to the WC-Co cemented carbide during the sintering process, internal defects and the standard deviation of fatigue life were reduced. (Received 1 October 2021; Accepted 6 December 2021)