本研究探討添加Na2SO4對420麻田散鐵不銹鋼於NaCl 水溶液中孔蝕行為影響。研究中使用使用市售420 type麻田散鐵不銹鋼進行1050 ∘C固溶均質化熱處理其後再於650∘C下進行回火熱處理。分別將只經固溶熱處理與再經回火熱處理之420 不銹鋼於0.1 M NaCl水液中添加0.0001 M~0.5 M Na2SO4，藉由動電位極化試驗與定電位試驗，比較兩種試片於各溶液環境中，Na2SO4對兩者孔蝕敏感性變化及差異。結果顯示未經回火熱處理之固溶試片具有較佳耐蝕性，但添加低濃度Na2SO4均使得兩者孔蝕起始電位降低，孔蝕敏感性增加，隨著添加更高濃度Na2SO4孔蝕敏感性降低甚至被抑制。而經回火熱處理420不銹鋼，於各種溶液中動電位極化掃描過程，於電位約為- 0.35 VSCE均可發現由碳化物周圍基材溶解所貢獻之陽極峰。
研究中並另以清淨度較高之420 SS作為清淨度影響的對照組進行相同實驗。結果顯示，高清淨度420不銹鋼於各溶液中均較經回火熱處理清淨度較低之420 不銹鋼耐蝕性佳。

In this study, the effects of sodium sulfate and its concentration on the passivation and pitting corrosion behaviors of 420 martensitic stainless steel in NaCl solution were investigated. The commercial 420 type martenstiic stainless steel were tempering at 650oC with a previous solution annealing and oil quenched at 1050o C. By potentiodynamic polarization curve and potentiostatic estimation to compare the results obtained with the solution annealed / oil qunched 420 SS and tempered 420 SS with previous annealed / queched in 0.1 M NaCl with 0.0001 M~0.5 M Na2SO4 addition. The results showed the solution annealed / qunched one has better corrosion resistance. Furthermore, the pitting corrosion susceptibility of solution annealed / qunched 420 SS and annealed / qunched / tempered 420 SS were increased if the Na2SO4 addition was lower, in contrast, inhibition of pitting corrosion was observed if the Na2SO4 addition was high. The potentiodynamic polarizationcurves of annealed / qunched / tempered 420 SS appeared active-to-passive transition peaks in NaCl solution(< 1M) with or without Na2SO4 addition.
In this work, the 420 martensitic stainless steel with high clearance also investigated followed the same methodology as the previous stated. The results showed that the higher clearance one has better corrosion resistance than less clearance in the test environments.

1. T. G. Gooch. , Welding processes for stainless steel,Welding J. 74 (1995) 213
2. R. M. Davison, ASM Handbook, vol. 13-corrosion, (1992) 547
3. D. H. Mesa, A. Torb, A. Sinatora and A. P. Tschiptschin, The Effect of Testing Temperature on Erosion-Corrosion of Martensitic Stainless Steel, Wear, 255 (2003) p.139
4. M.G. Fontana, Corrosion engineering, 3rd ed., McGraw Hill, (1896) 282
5. H. P. Leckie, H. H. Uhlig, Environmental Factors Affecting the Critical Potential for Pitting in 18-8 Stainless Steel, J. Electrochem. Soc., 113 (1966) 1262.
6. P. C. Pistorius, G. T. Burstein, Growth of corrosion pits on stainless steel in chloride solution containing dilute sulphate ,Corrosion Science, 33 (1992) 1885.
7. M. H. Moayed, R. C. Newman, Deterioration in critical pitting temperature of 904L stainless steel by addition of sulfate ions,Corrosion Science, 48 (2006) 3513.
8. B. Deng, Y. Jing, J. Liao, Y. Hao, C. Zhong, and J. Li, Dependence of critical pitting temperature on the concentration of sulphate ion in chloride-containing solutions, App. Surf. Sci. 253 (2007) 7369
9. S. Hastuty, A. Nishikata and Tooru Tsuru, Pitting corrosion of Type 430 stainless steel under chloride solution droplet,Corrosion Science, 52 (2010) 2035.
10. F. Matjaz, F. Stefan, N.Fabio, and M. Ingrid, Polyethyleneimine as a corrosion inhibitor for ASTM 420 stainless steel in near-neutral saline media , Corrosion Science, 51 (2009) 525.
11. Sedriks, A. John, Corrosion of Stainless steels, Ch.2 (1979), p. 32
12 P. Marcus, J. Oudar, Corrosion Mechanisms in Theory and Practice, Ch.7 (1995)
13 G S．Frankel，Pitting Corrosion of Metals, A Review of the Critical Factors , J. Electrochem. Soc., 145 (1998) 2198
14. H. H. Strehblow, Nucleation and Repassivation of Corrosion Pits for Pitting on Iron and Nickel, Werkst Korros, 27 (1976) 792
15. H. H. Strehblow, Corrosion Mechanisms in Theory and Practice, Marcel Dekker Inc., New York, (1995), p.201
16. T.P. Hoar, The relationships between anodic passivity, brightening and pitting, Corrosion Science, 5 (1965) 279
17 P. Marcus, J. M. Herbelin, The entry of chloride ions into passive films on nickel studied by spectroscopic (ESCA) and nuclear (36Cl radiotracer) methods, Corrosion Science, 34 (1993) 1123
18. T. P. Hoar, and W. R. Jacob, Breakdown of Passivity of Stainless Steel by HalideIons, Nature, 216 (1967) 129
19. T. P. Hoar, The relationships between anodic passivity, brightening and pitting, Corrosion Science, 5 (1965) 279
20. H. H. Uhlig, Adsorbed and reaction-production films on metals, J. Electrochem. Soc., 215C (1950), 97,
21. H. H. Strehblow, Corrosion Mechanisms in Theory and Practice, P. Marcus and J. Oudar, Editors, P.201, Marcel Dekker, Inc., New York (1995)
22. K. J. Vetter, H. H. Strehblow, and B. Bunsenges, Physical Chemistry, 74 (1970) 1024
23. N. Sato, A theory for breakdown of anodic oxide films on metals, Electrochim. Acta, 16 (1971) 1683
24. N. Sato, K. Kudo, and T. Noda, The anodic oxide film on iron in neutral solution, Electrochim Acta, 16 (1971) 1909
25. R. G. Kelly, in Proceedings of Corrosion, Research Topical Symposia, F Mansfeld, W. H. Smyrl, . M.Kendig, and B. Shaw, Editors, NACE, Houston, TX (1997) 81
26. A. Thrnbull, in Advances in Localized Corrosion, H. Isaacs, U. Bertocci, J. Kruger, and S. Smialowska, Editors, NACE-9, NACE, Houston, TX (1990) 359
27. M. A. Streicher, Pitting Corrosion of 18Cr-8Ni Stainless Steel, J. Electrochem. Soc., 375 (1956) 103
28. G. S. Eklund, Initiation of Pitting at Sulfide Inclusions in Stainless Steel, J Electrochem. Soc., 121 (1974) 467
29. N. Pessal, C. Liu, Determination of critical pitting potentials of stainless steels in aqueous chloride environments, Electrochim. Acta, 16 (1971) 1987
30. Y. Hisamatsu, T. Yoshii, and Y. Matsumurag, in Localized Corrosion, R. W. Staehle, B. F. Brown, J. Kruger, and A. Agrawal, Editors, NACE-3, NACE, Houston, TX (1974)
31. G. C. Wood, W. H. Sutton, J. A. Richardson, T. N. K. Riley, and A. G. Malherbe, in Localized Corrosion, R. W. Staehle, B. F. Brown, J. Kruger, and A. Agrawal, Editors, NACE-3, NACE, Houston, TX (1974)
32. G. S. Eklund, On the Initiation of Crevice Corrosion on Stainless Steel, J. Electrochem. Soc., 123 (1976) 170
33. A. F. Candelaria, C. E. Pinedo, Influence of the heat treatment on the corrosion resistance of the martensitic stainless steel type AISI 420, J. of Mat. Sci. Letter, 22 (2003) 1151
34. L.F. Alvarez and C. Garcia and V. Lopez, Continuous Cooling Transformations in Martensitic Stainless Steels, ISIJ Int. 34 (1994) 516.
35. L. L. Shreir, R. A. Jarman, and G. T. Burstein, Corrosion, 1 ( 2000) 36
36. J.Y. Park and Y.S. Park, The effects of heat-treatment parameters on corrosion resistance and phase transformations of 14Cr–3Mo martensitic stainless steel, Mater. Sci. and Eng., A 449-451(2007) 1131.
37. A.F. Candelaria, C. E Pinedo, Mater. Sci. Letters, 22 (2003) 1151.
38. P.D. Bilmes, C.L. Llorente, L. Saire Huamán, L.M. Gassa, and C.A. Gervasi, Microstructure and pitting corrosion of 13CrNiMo weld metals, Corrosion Science, 48 (2006) 326
39. C.T. Kwok, C. Man, F.T. Cheng, Cavitation erosion and pitting corrosion behaviour of laser surface-melted martensitic stainless steel UNS S42000, Surf.Coat. Technol. ,126 (2000) 238
40. P.D. Bilmes, C.L. Llorente, and C.M. Méndez, C.A. Gervasi, Microstructure, heat treatment and pitting corrosion of 13CrNiMo plate and weld metals, Corrosion Science 51 (2009) 876
41. G. R. Speich, W. C. Leslie, Tempering of steel, Material Transactions, 3 (1972) 1054.
42. R. C. Alkire, K. P. Wong, Corrosion Science, 28 (1988) 411
43. J. E. Truman, Corrosion Resistance of 13 percent Cr Steels as Influenced by Tempering Treatments, British Corr. J., 11 (1976) 92
44. Baihe Miao, D.O. Northwood, L.C. Lim, M.O. Lai, Microstructure of tempered AISI 403 stainless steel, Materials science and engineering, A171 (1993) 21
45. H.Bayati, Mater. Sci. Technol.,11 (1995) 118.
46. T.Bell , J.B. Cohen, Heat Treating, ASM International, (2000) 535
47. A. Philip Schweitzer, P. E., Corrosion Engineering Handbook, Marcel Dekker Inc. (1996) 555
48. D. Landolt, Corrosion and Surface Chemistry of Metals, CRC. Prees. ,(2007) 544
49. A. L. Schaeffler, Constitution diagram for stainless steel weld metal Met. Prog., 56 (1949) 56.
50. P. Ernst and R. C. Newman, Pit growth studies in stainless steel foils. I. Introduction and pit growth kinetics, Corrosion Sci., 44(2002) 927
51. D.D MacDonald, D. Owen, J. Electrochem. Soc. 134 (1973) 317