Papers by Author: Yue Xin Ma

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Authors: Shao Kui Yang, Long Wang, Yue Xin Ma
Abstract: This document introduces tentative designs of the cold extruding of thin wall ultra-deep blind hole about 7A04 recoil spring tube, its technical process and experimental result and analyses the existed problems and the reasons. These experimental studies have reference value for taking cold extrusion shape of 7A04 and ultra-deep hole.
Authors: Yue Xin Ma, Yue Jun Liu, Long Wang, De Chang Zeng, Yu Hua Tan
Abstract: The microstructures of 11 kinds of commercial steels quenched from high temperature were deeply studied by optical microscope and canning election microscope. It was proved that packet martensite in medium and high carbon steels is not lath martensite, but rather packet plate martensite. Through the analysis of crystallography,it was found that four change rules of crystal orientation may arise during the process of martensite transformation. Two inner interfaces spontaneously formed were only discovered in martensite transformation process: small-angel boundary (misorientation angle is 0 ~ 10º) and twin boundary (misorientation angle is 70º32’). The former mainly appeared in low carbon martensite, and the latter principally formed in medium and high carbon martensite. The twin boundary packet mechanism in medium and high carbon steels has made in detail in this paper.
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