| FENG Zhi-guo,ZHAO Xun-feng,LIU Jing.Effects of Heating Source on Microstructure and Properties of 38CrMoAl Steel Nitrided Layer[J],48(6):173-179 |
| Effects of Heating Source on Microstructure and Properties of 38CrMoAl Steel Nitrided Layer |
| Received:October 28, 2018 Revised:June 20, 2019 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2019.06.020 |
| KeyWord:38CrMoAl steel electromagnetic induction heating plasma nitriding vacuum nitriding microstructure |
| Author | Institution |
| FENG Zhi-guo |
1.Guizhou University, Guizhou , China |
| ZHAO Xun-feng |
1.Guizhou University, Guizhou , China |
| LIU Jing |
2.Guizhou Normal University, Guizhou , China |
|
| Hits: |
| Download times: |
| Abstract: |
| The work aims to study the influence rules of the heating mechanism of electromagnetic induction, plasma bom-bardment and resistance heat on the microstructure of nitriding layer in nitriding process. 38CrMoAl steel was treated by elec-tromagnetic induction vacuum pulse, plasma and vacuum nitriding technology. OM, SEM, XRD, EBSD and automatic micro-hardness tester were carried out to detect and analyze the microstructures, phase composition, crystal phase and hardness gradient of these nitriding layers. After 38CrMoAl steel were nitrided by three methods respectively, the nitriding layers were mainly Fe2N and Fe3N phase structure, and small-sized crystal grains of 0.5~2.5 μm and misorientation of less than 5° were distributed. The electromagnetic induction heating facilitated the nitriding layer to obtain a higher content of ε phase and a thicker white bright layer, resulting in a surface hardness of 1200HV0.5 and uneven transition layer. Under the plasma bombardment, the nitrogen ion diffusion ability was relatively strong, resulting in the thickness of the nitriding layer of 38CrMoAl steel up to 240 μm and the distribution of small grain size of 0.5~2.5 μm and the misorientation of less than 5° were 81% and 73% respectively. However, after the vacuum nitridation of 38CrMoAl steel by resistance heating, the thickness of the nitriding layer was only 90 μm, and the distribution of the small-sized grain and the small angle misorientation in the nitriding layer were 76.4% and 71.9%. The skin effect of electromagnetic induction heating helps the nitriding layer to obtain high nitrogen content and high surface hardness. Plasma bombardment enhances the diffusion of nitrogen atoms and refines the microstructure of the grains, and obtains excellent microstructure and performance. The resistance heating method cannot provide a concentrated reaction environment, so the nitriding efficiency and the nitride layer performance are weaker than the former two. |
| Close |
|
|
|