Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


공학

한국표면공학회지 (37권4호 234-241)

Improvement of the Resistance to Cavitation Erosion by the Formation of $eta$` Martensite in Flame-Quenched Cu-9Al-4.5Ni-4.5Fe Alloys

화염급냉 표면처리된 Cu-9Al-4.5Ni-4.5Fe 합금의 $eta$` 마르텐사이트 형성에 의한 케비테이션 침식 저항성 향상에 관한 연구

홍성모;이민구;김광호;김경호;김흥회;홍순익;

충남대학교 금속공학과;한국원자력연구소 원자력재료기술개발부;충남대학교 재료공학과;

Abstract

Cavitation erosion properties of the Cu-9Al-4.5Ni-4.5Fe alloys (Al-bronze) surface-modified by flame quenching process have been investigated. After flame quenching at above $T_{eta}$, the surfaces of Al-bronze with $alpha$ + $ extsc{k}$ structure have been changed into the $alpha$ + $eta$` martensite phases by the eutectoid reaction of $alpha$ + $ extsc{k}$longrightarrow$eta$ followed by the martensite transformation of $eta$longrightarrow$eta$`. As a result of cavitation test, the measured incubation time and erosion rate of the $alpha$ + $eta$` alloy was 1.2 times higher and 1.5 times lower, respectively, compared to those of the conventional $alpha$ + $ extsc{k}$ alloys, showing a remarkable increase of cavitation resistance with the formation of $eta$` martensite. This is attributed to a preferential erosion of the $ extsc{k}$ precipitates that show the lowest resistance among the $alpha$, $ extsc{k}$, $eta$` phases under cavitation loading.ases under cavitation loading.

Keywords

Cavitation;Al-bronze;Pump impeller;Erosion;Flame quenching;Surface treatment;Martensite;