Effect of Cryogenic Treatment on the Relative Length Change and Wear Behaviour of AISI D2 Cold-Work Die Steel

• Main Authors: Huan-Chen Liao, 廖桓震
• Other Authors: Liu-Ho Chiu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/91539339952363128022

碩士 === 大同大學 === 材料工程學系(所) === 100 === Three cold-work steeels, standard B, P(AISI D2) and modified D (DC53), have been vacuum heat treated by using different quenching and tempering processes to observe the change of microstructure, hardness, wear resistance and the relative length change. The conditions was austenitized at 1000~1050℃ for 20 min, cryogenic treatment at －90℃ and －160℃, and tempered at 200℃~650℃. The specimens always exist retained austenite after heat treatment and cryogenic treatment. A part of unstable retained austenite will be transformed into stable martensite with time, and further, retaned austenite and martensite have different volume so it will cause volume expansion or crack. In order to observe the effect of steels in the phenomenon, I measure the percent of retained austenite and the relative length change each 3 month. The results shows that wear resistance of modified D(DC53) was better than standard B and P(AISI D2). The percent of retained austenite will be decreased gradually in 6 months, but the relative length change was not unity.