Effect of pre-nitriding on corrosion resistance of 20CrMnTi steel vacuum carburized layer

doi:10.13251/j.issn.0254-6051.2022.10.036

Abstract

Abstract: 20CrMnTi steel was pre-nitrided before vacuum carburizing, and the effect of pre-nitriding treatment on microstructure of the carburized layer and the morphology of the corroded surface was investigated by means of OM, SEM and XRD, and the corrosion resistance was evaluated by electrochemical tests and corrosion rate calculated by mass loss. The results show that the martensite of the carburized layer of the pre-nitrided and carburized specimen is finer with a large amount of cementite precipitates, and the corrosion resistance is significantly improved. The corrosion rate and the tendency of corrosion to occur are greatly reduced, the self-corrosion current density is reduced from 1.3608×10^-5 mA·cm^-2 to 2.9817×10^-6 mA·cm^-2 and the self-corrosion potential is increased from -0.7741 V to -0.6672 V, the corrosion rate calculated by mass loss is only half of that of the carburized specimen. This is mainly due to the finer martensite and cementite of the pre-nitrided and carburized specimen hindering the expansion of pitting and thus reduce the corrosion rate, and the nitrogen atoms in carburized layer will react chemically with the solution to generate NH⁺₄ and NO^-₂ or NO^-₃, which will reduce the corrosion effect of Cl^-.

Key words: 20CrMnTi steel, pre-nitriding, vacuum carburizing, microstructure, corrosion resistance, pitting

CLC Number:

TG156.8

Li Zhuocheng, Tian Yong, Wang Bin, Wang Haojie. Effect of pre-nitriding on corrosion resistance of 20CrMnTi steel vacuum carburized layer[J]. Heat Treatment of Metals, 2022, 47(10): 211-217.

References

[1]Yang Q X, Ren X J, Gao Y K, et al. Effect of carburization on residual stress field of 20CrMnTi sample and its numerical simulation[J]. Materials Science and Engineering A, 2005, 392(6): 240-247.
[2]罗红丽. 20CrMnTi钢表面化学镀层与渗碳层耐磨、耐蚀性的对比研究[D]. 镇江: 江苏大学, 2015.
Luo Hongli. Comparative study of wear and corrosion resistance of electroless plating coating and carburization layer on 20CrMnTi steel[D]. Zhenjiang: Jiangsu University, 2015.
[3]杨武, 顾濬祥, 黎樵燊, 等. 金属的局部腐蚀[M]. 北京: 化学工业出版社, 1995.
[4]张艳, 李倩, 张媛. 904L不锈钢在5 g/L H₂SO₄溶液中的腐蚀行为[J]. 沈阳工业大学学报, 2015, 37(2): 236-239.
Zhang Yan, Li Qian, Zhang Yuan. Corrosion behavior of 904L stainless steel in 5 g/L H₂SO₄solution[J]. Journal of Shenyang University of Technology, 2015, 37(2): 236-239.
[5]Carboni C, Peyre P, Berander G, et al. Influence of high power diode laser surface melting on the pitting corrosion resistance of type 316L stainless steel[J]. Journal of Materials Science, 2002, 37(17): 3715-3720.
[6]曾洪涛, 向嵩, 刘松林, 等. 904L不锈钢在氢氟酸和浓硫酸混合液中的腐蚀行为[J]. 中国腐蚀与防护学报, 2013, 33(3): 182-187.
Zeng Hongtao, Xiang Song, Liu Songlin, et al. Corrosion behaviors of 904L austenite stainless steel in concentrated sulfuric acid containing hydrofluoric acid[J]. Journal of Chinese Society for Corrosion and Protection, 2013, 33(3): 182-187.
[7]刘悦, 吴红艳, 杜林秀. 铁路车辆用V-N-Cr微合金化Q690高强耐候钢组织性能和腐蚀行为[J]. 材料工程, 2021, 49(4): 111-119.
Liu Yue, Wu Hongyan, Du Linxiu. Microstructure and corrosion behavior of V-N-Cr microalloyed Q960 high strength weathering steel for rail way vehicles[J]. Journal of Materials Engineering, 2021, 49(4): 111-119.
[8]Jargelius-Pettersson. Electrochemical investigation of the influence of nitrogen alloying on pitting corrosion of austenitic stainless steels[J]. Corrosion Science, 1999, 41(8): 1639-1664.
[9]林玉珍, 杨德钧. 腐蚀和腐蚀控制原理[M]. 北京: 中国石化出版社, 2014: 214.
[10]Mouri L, Mabille I, Fiaud C, et al. Improvement of the corrosion resistance of a low carbon steel using a two step plasma treatment[J]. Corrosion Science, 2002, 44(9): 2089-2099.
[11]曹楚南. 腐蚀电化学原理. [M]. 3版. 北京: 化学工业出版社, 2008: 122-194.
[12]Song D, Ma A B, Jing J H, et al. Corrosion behavior of bulk ultra-fine grained AZ91D magnesium alloy fabricated by equal-channel angular pressing[J]. Corrosion Science, 2011, 53(1): 362-373.
[13]Ly R, Karayan A I, Hartwig K T. Insights into the electrochemical response of a partially recrystallized Al-Mg-Si alloy and its relationship to corrosion events[J]. Electrochimica Acta, 2019, 308: 35-44.
[14]Shi Z M, Liu M, Atrens A. Measurement of the corrosion rate of magnesium alloys using Tafel extrapolation[J]. Corrosion Science, 2010, 52(2): 579-588.
[15]Ambat R, Aung N N, Zhou W, et al. Corrosion behavior of Mg-Zn-Y Alloy with long-period stacking ordered structures[J]. Journal of Materials Science and Technology, 2012, 28(12): 1157-1162.
[16]由园. C-N(-La)共渗层原子间作用第一原理计算与N扩散分子动力学模拟[D]. 哈尔滨: 哈尔滨工业大学, 2013.
You Yuan. First-principles calculations of interatomic interactions and molecular dynamics simulation of N diffusion in rare-earth nitrocarburized layers[D]. Harbin: Harbin Institute of Technology, 2013.
[17]Chyou S D, Shih H C. Structure and electrochemical properties of plasma-nitrided low alloy steel[J]. Materials Science and Engineering A, 1990, 129(1): 109-117.
[18]Palit G C, Kain V, Gadiyar H S. Electrochemical investigations of pitting corrosion in nitrogen-bearing type 316LN stainless steel[J]. Corrosion, 1993, 49(12): 977-991.
[19]Tsai W T, Reynders B, Stratmann M, et al. The effect of applied potential on the stress corrosion cracking behavior of high nitrogen steels[J]. Corrosion Science, 1993, 34(10): 1647-1656.
[20]Clayton C R, Rosenzweig L, Oversluizen M, et al. Influence of nitrogen on the passivity of 18-8(0.24%N) stainless steels[J]. Electrochemical Society, 1986, 86(7): 323-339.