| LI Run-tao,SUN Fei,WANG Dan-dan,WEI Kun-xia,YANG Wei-min,HU Jing.Effect of Low Temperature Plasma Nitriding with Ti Catalyst on the Microstructure and Properties of 304 Stainless Steel[J],52(10):422-429 |
| Effect of Low Temperature Plasma Nitriding with Ti Catalyst on the Microstructure and Properties of 304 Stainless Steel |
| Received:August 03, 2022 Revised:February 16, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.10.038 |
| KeyWord:Ti catalyst plasma nitriding 304 austenitic stainless steel corrosion resistance hardness wear resistance |
| Author | Institution |
| LI Run-tao |
Jiangsu Key Laboratory of Materials Surface Science and Technology,Jiangsu Changzhou , China;National Experimental Demonstration Center for Materials Science and Engineering, Changzhou University, Jiangsu Changzhou , China |
| SUN Fei |
Jiangsu Key Laboratory of Materials Surface Science and Technology,Jiangsu Changzhou , China;Institute of Modern Equipment Manufacturing, Changzhou Institute of Industry Technology, Jiangsu Changzhou , China |
| WANG Dan-dan |
Jiangsu Key Laboratory of Materials Surface Science and Technology,Jiangsu Changzhou , China;National Experimental Demonstration Center for Materials Science and Engineering, Changzhou University, Jiangsu Changzhou , China |
| WEI Kun-xia |
Jiangsu Key Laboratory of Materials Surface Science and Technology,Jiangsu Changzhou , China;Huaide College, Changzhou University, Jiangsu Jingjiang , China |
| YANG Wei-min |
Jiangsu Key Laboratory of Materials Surface Science and Technology,Jiangsu Changzhou , China;National Experimental Demonstration Center for Materials Science and Engineering, Changzhou University, Jiangsu Changzhou , China |
| HU Jing |
Jiangsu Key Laboratory of Materials Surface Science and Technology,Jiangsu Changzhou , China;National Experimental Demonstration Center for Materials Science and Engineering, Changzhou University, Jiangsu Changzhou , China;Huaide College, Changzhou University, Jiangsu Jingjiang , China |
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| Abstract: |
| 304 austenitic stainless steel has excellent corrosion resistance, but its poor hardness and wear resistance make it hard to meet the requirements in some applications, and thus surface modification is required to promote its practical applications. Plasma nitriding (PN) is a widely used surface modification technology, while higher temperature plasma nitriding results in a decrease of the corrosion resistance and lower temperature plasma nitriding (LPN) brings about quite low efficiency. In order to overcome the problems in the traditional plasma nitriding, low temperature plasma nitriding with Ti catalyst is primarily proposed in this study, and the research aims to effectively enhance the hardness and wear resistance without reduction of corrosion resistance and with high efficiency. To reach this research goal, low temperature plasma nitriding with Ti catalyst (LPNTi) was conducted at 420 ℃ for 4 h by putting some amount of sponge titanium around the samples during plasma nitriding, and the effect of plasma nitriding with Ti catalyst on the microstructure and properties of 304 austenitic stainless steel was systematically investigated by optical microscope, SEM, EDS, X-ray diffractometer (XRD), microhardness tester, friction and wear tester, electrochemical workstation, etc. The results indicated that excellent corrosion resistance of 304 austenitic stainless steel was kept and even turned to be better after plasma nitriding with Ti catalyst compared with that under traditional plasma nitriding, with the corrosion potential increasing from –320.77 mV to –316.68 mV. SEM, XRD and EDS analysis showed that LPNTi layer was mainly composed of S phase, αN and a little Ti2N with high hardness, which meant that Ti was helpful for the phase transformation of γ to α, and αN was formed due to this phase transformation. The surface hardness could be significantly enhanced from 978HV0.025 by plasma nitriding to 1350HV0.025 by plasma nitriding with Ti catalyst due to the double strengthening effect from αN and Ti2N, which was more than 6 times of 208HV of the matrix. Meanwhile, the wear resistance was dramatically enhanced, the friction coefficient decreased from 0.96 to 0.42, the weight wear rate decreased from 20.9 μg/(N.m) to 7.4 μg/(N.m), decreasing by about 2/3, and the wear marks became much narrower and shallower and the wear area was reduced greatly. More importantly, the nitriding efficiency was remarkably improved as well, with the thickness of nitrided layer increasing from 11.37 um by PN to 48.32 um by LPNTi under the same nitriding condition of 420 ℃/4 h, more than 4 times thicker than that by PN. In all, the excellent corrosion resistance of 304 austenitic stainless steel can be held and even becomes better after low temperature plasma nitriding with Ti catalyst (LPNTi) treatment. The surface hardness and wear resistance can be dramatically enhanced due to the formation of S phase strengthened by αN and a little Ti2N. More importantly, the treatment efficiency of plasma can be remarkably improved, which is more than 4 times of that by plasma nitriding. |
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