摘要: |
在双相不锈钢等离子体渗氮表面改性过程中,为了避免N原子与Cr原子结合形成CrN的析出使基体中Cr元素含量减少进而降低双相不锈钢的耐蚀性能,通常渗氮温度选取低于450 ℃。温度低,N原子的扩散速率慢,存在渗氮时间长,渗氮层较薄等问题。对SS2205双相不锈钢在不同时间进行了高温快速离子渗氮研究,结果表明:在540 ℃条件下,渗氮时间为1 h时,可得到8 μm厚且没有明显CrN析出的渗氮层,使其表面硬度显著提高;与440 ℃、4 h条件下得到的渗氮层相比,厚度增加了一倍,表面硬度提高50%左右,且耐点腐蚀性能并没有严重下降。 |
关键词: SS2205双相不锈钢 等离子体渗氮 耐点蚀性 |
DOI:10.11933/j.issn.1007-9289.2015.05.007 |
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Surface Modification on Duplex Stainless Steels by High Temperature Rapid Plasma Nitriding |
DONG Hezhen, XU Jiujun, WANG Liang
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College of Transportation Equipments and Ocean Engneering, Dalian Maritime University
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Abstract: |
In the surface modification process of duplex stainless steel using plasma nitriding, N atoms combine with Cr atoms of duplex stainless steel to precipitate CrN, resulting in the reduction of Cr elements in the matrix and then the decrease of the corrosion resistance of duplex stainless steel. To overcome these defects unentioned above, the nitriding temperature is generally selected below 450 ℃. However, the diffusion rate of nitrogen atoms is much lower at low temperature, leading to the long nitriding time and thin nitriding layer. In this paper, the high temperature rapidly plasma nitriding of SS2205 duplex stainless steel with different time was studied. The results show that when the nitriding temperature is 540 ℃ and the nitriding time is 1 h, a nitriding layer of 8 μm in thickness can be obtained on the surface of duplex stainless steel without obvious CrN precipitation. Compared with the nitriding layer obtained at 440℃ for 4 h, the thickness is doubled and the surface hardness is also improved about 50%, while the pitting corrosion resistance is not damaged seriously. |
Key words: SS2205 duplex stainless steel plasma nitriding pitting corrosion resistance |