Fe-Ni燒結硬化合金鋼中Ni之均質化及機械性質改善對策
Improvement on the Homogenization of Ni in Fe-Ni Sinter-Hardening Alloy Steels
Date Issued
2007
Date
2007
Author(s)
Tsai, Chia-Cheng
DOI
zh-TW
Abstract
Metal injection molding (MIM) process has many advantages in making small parts with complicated shapes over the press-and-sinter process and other manufacturing processes. The MIM parts usually must attain high sintered densities and good mechanical properties through high temperature sintering and heat treatment. However, the quenching process will cause problems in distortion and dimensional control. Thus, sinter-hardening process has become a focus of recent MIM industries. In this study, compositions and processing parameters of Fe-8Ni MIM 2700 alloys were adjusted in order to improve the mechanical properties of the sinter-hardened parts without the need of quenching.
The results show that fine Ni powders reduced the diffusion distance and improved the homogeneity of Ni and C in the matrix. The addition of Cr also had similar effect. It was found from the carburization test of Fe-Ni alloys that the presence of Cr helped reduce the repulsion effect between carbon and nickel. Thus, the homogeneity of C and Ni was improved and the mechanical properties were enhanced. The use of prealloyed powder showed no improvement due to the decrease of sintered density when the same sintering temperature was used despite that the Ni was uniformly distributed. The employment of cryogenic treatment after sintering caused transformation of the retain austenite to martensite and thus could increase the tensile strength and hardness.
Subjects
金屬粉末射出成形
燒結硬化型合金鋼
超深冷處理
粉末冶金
燒結
Metal injection molding
powder injection molding
sinter-hardening,homogenization
powder metallurgy.
Type
thesis