Heat Treatment of Metals ›› 2022, Vol. 47 ›› Issue (9): 1-5.DOI: 10.13251/j.issn.0254-6051.2022.09.001

• PROCESS RESEARCH •     Next Articles

Effect of vacuum low pressure carburizing on microstructure and properties of austenitic stainless steels 304 and 316L

Cheng Ru1, Tian Yong1, Song Chaowei1, Wang Haojie2   

  1. 1. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang Liaoning 110819, China;
    2. School of Mechanical Engineering, Shenyang University of Technology, Shenyang Liaoning 110870, China
  • Received:2022-04-20 Revised:2022-07-01 Published:2022-10-18

Abstract: Surface strengthening of 304 and 316L austenitic stainless steels was processed by using vacuum low pressure carburizing process. The microstructure, phase composition and microhardness distribution of the carburized layers were analyzed by means of optical microscope, scanning electron microscope, Thermo-Calc software, X-ray diffractometer and microhardness tester. The offsets of different diffraction peaks in the carburized layers and the changes in lattice parameters before and after carburizing of the tested steels were calculated. Combined with the effects of molybdenum on carburizing process of the austenitic stainless steels, the differences in the carburized layer thickness, surface hardness and mechanism of carbides precipitation after carburizing of 304 and 316L austenitic stainless steels were compared and studied. The results show that the carburized layers produced by 750 ℃ carburizing for 2.6 h are composed of expanded austenite and Cr23C6 phases, the austenite lattice constant has increased by 1.33% and 1.14% respectively for 304 and 316L stainless steels, and Cr23C6 is mainly precipitated in strip shape on the expanded austenite grain boundaries. The surface hardness of the 304 and 316L stainless steels after carburizing at 750 ℃ for 2.6 h is over 2 times higher than that of substrate.

Key words: austenitic stainless steel, vacuum low pressure carburizing, lattice expansion, carbides

CLC Number: