산질화처리가 저탄소강의 미세조직과 나노경도 및 부식특성에 미치는 영향 |
조영욱1, 원종호1, 우정호2, 유상호3, 조영래1 |
1부산대학교 재료공학과 2㈜한국클래드텍 3㈜세 텍 |
Effect of Oxi-Nitrocarburizing on the Microstructure, Nanohardness and Corrosion Properties for Low Carbon Steel |
Young-Wook Cho1, Jong-Ho Won1, Jeong-Ho Woo2, Sang-Ho Yu3, Young-Rae Cho1 |
1School of Materials Science and Engineering, Pusan National University, Busan 46241, Republic of Korea 2Korea Clad Tech Co. Ltd., Daegu 48013, Republic of Korea 3SEHTec Co. Ltd., Incheon 22669, Republic of Korea |
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Received: 5 September 2017; Accepted: 16 January 2018. Published online: 5 April 2018. |
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ABSTRACT |
Oxi-nitrocarburizing treatment was performed to improve the anti-corrosion and anti-wear properties of low carbon steels. The oxi-nitrocarburizing was carried out in 2 steps: a gas nitrocarburizing step at 560 ℃ and an oxidation step at 550 ℃ for 30 min with steamed water. The mechanical and chemical properties of the samples were then measured using nanoindentaion test with a load of 10 mN and salt spray test. Investigation on the surface hardening layer with scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and electron prove microanalysis (EPMA) were also carried out. The thickness and nanohardness of the oxide layer were about 4 μm and 470 Hv, respectively. The oxi-nitrocarburized sample fabricated by gas nitrocarburizing for 50 min followed by oxidation for 30 min showed much better anticorrosion property than the sample prepared by the conventional gas nitrocarburizing method for 100 min. The improved anti-corrosion property of the oxi-nitrocarburized samples was due to the formation of a dense magnetite (Fe3O4) layer during the oxidation process on the porous nitride layer. These results indicate that oxi-nitrocarburizing is effective for surface treatment of low carbon steels with high anti-corrosion and high wear resistance. |
Keywords:
oxi-nitrocarburizing, low carbon steel, nanoindentation, nitride layer, oxide layer |
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