ステンレス鋳鋼の高温水中SCC進展挙動 ― 腐食電位，鋼種， …

1 2011, , 158-169. SCC .. SCC Growth Behavior of Cast Stainless Steels in High-Temperature Water Influences of Corrosion Potential, Steel Type, Thermal Aging and Cold-Work . Takuyo Yamada Takumi Terachi . Tomoki Miyamoto Koji Arioka . 158. SCC .. SCC Growth Behavior of Cast Stainless Steels in High-Temperature Water Influences of Corrosion Potential, Steel Type, Thermal Aging and Cold-Work . 1 2. Takuyo Yamada Takumi Terachi . 1 1. Tomoki Miyamoto Koji Arioka . SCC BWR . SCC . PWR 1 . SCC PWR 1 . BWR PWR SCC . PWR1 SCC . 400 4 . 10% . SCS14A SCS13A 10% . SCC . SCC 400 4 . SCC PWR1 . SCC SCS14A. SCS13A 400 4 10% SCC . SCS14A SCS13A SCC 400 . 1 SCC 400 . 4 SCC . SCC . SCC . SCC . Abstract Recent studies on crack growth rate CGR measurement in oxygenated high-temperature pure water conditions, such as normal water chemistry NWC in BWRs, using compact tension CT type specimens have shown that stainless steel weld metal are susceptible to stress corrosion cracking SCC.

2 On the other hand, the authors reported that no significant SCC growth was observed on stainless steel weld metals in PWR primary water at temperatures from 250 to 340 . Cast austenitic stainless steels are widely used in light water reactors, and there is a similarity between welded and cast stainless steels in terms of the microstructure of the ferrite/austenite duplex structure. However, there are a few reports giving CGR data on cast stainless steels in the BWRs and PWRs. The principal purpose of this study was to examine the SCC growth behavior of cast stainless steels in simulated PWR. primary water. A second objective was to examine the effects on SCC growth in hydrogenated and oxygenated water environments at 320 of : 1 corrosion potential ; 2 steels type Mo in alloy ; 3 thermal-aging up to 400 x40kh ; and 4 cold-working 10% . The results were as follows : 1 No significant SCC growth was observed on all types of cast stainless steels: aged 400 40 kh of SCS14A and SCS13A and 10% cold-working, in hydrogenated low-potential water at 320.

3 2 Aging at 400 40 kh SCS14A 10%CW . markedly accelerated the SCC growth of cast material in high-potential water at 320 , but no significant SCC growth was observed in the hydrogenated water, even after long-term thermal 1 . 2 . 159. aging 400 40 kh . 3 Thus, cast stainless steels have excellent SCC resistance in PWR. primary water. 4 On the other hand, significant SCC growth was observed on all types of cast stainless steels: 10%CW SCS14A and SCS13A, in 8 ppm-oxygenated high-potential water at 320 . 5 No large difference in SCC growth was observed between SCS14A Mo and SCS13A. 6 No large effect on SCC growth was observed in specimens before and after aging up to 400 for 10 kh. 7 Long-term aging at 400 for 40 kh markedly accelerated the SCC. growth of cast stainless steel. According to these results, a clear corrosion potential dependence on SCC growth behavior of cast stainless steels was recognized.

4 Keywords cast stainless steels, stress corrosion cracking SCC in high-temperature water, SCC growth rate, corrosion potential, cold-work, light water reactor 1. 20% SCC . 12 - 14 .. 316L BWR PWR . SCC 13 . - 14 .. 1 .. stress . corrosion cracking, SCC .. SCC . PWR1 . SCC . SCC SCC . boiling water reactor, BWR .. SCC SCS14A 316 SCS. 1 . 13A 304 PWR SCS. 14A SCS13A . BWR normal water chemistry, . NWC . hydrogen water chemistry, HWC 8 23%. SCC . 2 5 . - 400 . BWR NWC SCC 4 . 6 9 . - 8 23%. Pressurized water reactor, . PWR 1 .. BWR NWC SCC . SCC 15 . 16 . , . 10 . 11 . , 8 23% . SCC 400 1 . PWR 1 316L . 308L 400 1 400 3 . 160. 2.. 100kJ/mol 400 . 6 . 320 60 SCS14A ASTM. CF8M SCS13A ASTM CF8. 400 4 SCS14A . 8 15 23% SCS14A F8 .. SCS14A F15 SCS14A F23 . 10% cold work, CW 3 SCS13A 8 15% . 2 - 5 . 10 . , 11 . , SCS13A F8 SCS13A F15 . 2 . inter-granular stress corrosion cracking, IGSCC 400 4.

5 10% . SCC 10CW SCS14A. 17 . 1 . SCC . 10% . 1 SCS14A wt% . 2 SCS13A wt% . a SCS14A F8 b SCS14A F15 c SCS14A F23 . SCS14A . 161. 3 . , Type CW(%). (MPa) (MPa) (%) HV(1kg). SCS14A 400 . 0 231. (F23) 30,000h . 10 463 630 50 262. SCS14A.. (F15) 400 . 0 174. 30,000h . 10 436 525 55 214. SCS14A.. (F8) 400 . 10 462 601 54 225. 40,000h SCS13A. 10 424 702 47 258. (F15). 10 477 625 36 235. SCS13A.. (F8) 400 . 10 236. 10,000h . 4 .. SCC K . Type CW(%) . (MPa m) h .. SCS14A 400 . 0 DH 7, 18 . (F23) 30,000h T-S ASTM E399 . DO compact tension, CT . 10. 1/2 T SCS14A. DH (F15). 1 2 . 400 . 3 SCS14A Mo 30,000h 0 DH 9,529. SUS316 SCS13A Mo . DO SUS304 10. DH SCS14A. SCC (F8). DO 400 . 10. 40,000h SCC 1 500ppmB DH + 2ppmLi 30cc-STP/kg-H2O. DO DH 8 SCS13A. 10. ppm DO (F15). DH . DO 10. DH 10 . DH R= SCS13A. (F8). DO 400 . 10. 4 1 10,000h DH . 162. 3mm 400 4 SCC . 2 . SCC IG . scanning SUS316 10.

6 11 . , . electron microscopy, SEM SCC .. a . 3 SCS13A SCC .. t . SEM . 3 3 a . b c . SCC mm/s =a mm /t s SCS13A F15 +10CW T-S . SCS13A. F8 . +10CW. T-S . SCS13A. 3. F8 . 400 1 +10CW. T-S .. SCS13A SCC . DO SCC 400 1 SCC . 3 . 320 DO SCS14A . IG . SCC 2 SUS304 10 . 11 . , . SEM 2 4 5 DO SCC .. 2 a . b . c SCS14A 4 a SCS14A F8 +10CW. F15 +10CW. T-S SCS14A. F8 T-S b SCS13A F8 +10CW. +10CW. T-S SCS14A. F8 . 400 4 T-S . electron back scattering +10CW. T-S diffraction, EBSD . SCS14A SCC SCC . a SCS14A F15 b SCS14A F8 c SCS14A F8 . +10CW T-S +10CW T-S +10CW T-S . 320 500ppmB+2pmLi, 8ppm DO2 K 30 MPa m .. 400 40,000h 2 SCC SCS14A .. SEM . 163. a SCS13A F15 b SCS13A F8 c SCS13A F8 . +10CW T-S +10CW T-S +10CW T-S . 320 500ppmB+2pmLi, 8ppm DO2 K 30 MPa m .. 400 10,000h 3 SCC SCS13A .. SEM . a SCS14A F8 +10CW T-S b . SCS13A F8 +10CW T-S . 320 500ppmB+2pmLi, 8ppm DO2 K 30 MPa m . SCC EBSD.

7 164. a SCS14A F15 +10CW T-S b SCS14A F8 +10CW T-S . 400 40kh 320 500ppmB+2pmLi, 8ppm DO2 K 30 MPa m . 5 SCC SEM . TGSCC.. / SCC . IGSCC. / 1 . / IGSCC / SCC . 6 - 9 . DH SCC . SCC SCC . 5 a SCS14A. F15 +10CW SCS14A SCS13A . T-S SCC . 7 23% . 10CW .. 5. b . SCS14A. F8 400 4 +10. CW. T-S .. SCC SCC . -TG 400 . HV. 25g = 750 8 . DO SCS14A SCS13A SCC . SCC 400 1 . DH SCC 400 . 4 . DH SCC 15% SCS14A . 10CW SCS14A =. 6 6 2 15% SCC . 3 . SCC 7 . 15 23% DH DO . 165. a SCS14A F15 b SCS14A F8 c SCS14A F8 . +10CW T-S +10CW T-S +10CW T-S . d SCS13A F15 e SCS13A F8 f SCS13A F8 . +10CW T-S +10CW T-S 2+10CW T-S . 320 500ppmB+2pmLi, DH : 30cc-STP/kg-H2O K 30 MPa m .. 400 40,000h 400 10,000h 6 SCC . 9 SCC .. SUS316 DO . DH SCC . 10 . DO 400 4 . SCC . a SCS14A F23 b SCS14A F15 . SUS316 290 SCC . 7, 9,529h SCC . SUS316 SCC . 320 500ppmB+2pmLi, DH : 30cc-STP/kg-H2O . K 30 MPa m DO .. 400 30,000h SCC.

8 400 4. 7 SCC . SCS14A SCS13A . SCC . 400 4 DH SCC . SCC SUS316 SCC . SCC .. DO DH SCC. 3 SCC . 166. SCC DO . SCC . SCC . PWR1 SCC . SCC.. SCC . SCC .. SCC SCC .. CT . 10 10 a DH .. b . DO .. DO .. DH .. SCC .. PWR1 . SUS316 20CW . DO DH SCC . SCC . DH SCC . / / . SCS14A SCS13A 400 4 . 7 23% DH . 400 4 SUS316 SCC . 10% 320 1 DH / / . SCC .. SCC . 4. 5 a DO . SCC . 320 SCC . PWR1 SCC . 167. SCS14A. F15 . +10CW. T-S SCC .. DO SCC . DH 4 a . 11 SCS14A . / -IG . F15 F23 . SCC SUS316 . 5 a . SCC 12 SCS14A. F8 . EBSD . a DH 41 b DO 28 . 10 SCS14A F8 +10CW . a SCS14A F8 b SCS14A F15 c SCS14A F23 . 11 . 168. 5.. 5mm . 1 SCC . / . / SCC . 320 500ppmB+2ppmLi DH : . 30cc-STP/kg-H2O . 2 3 SCS14A SCS13A 10% . SUS316 SUS304 SCC . Cr . SCC . 5 400 4 . Cr SCC . 25% . 20% PWR1 . Cr 20%Cr SUS316 SCC . 16%Cr 4% SCC . SCC Cr 19 3 . PWR1 Cr . SCC . Cr SCC . Cr .. 320 500ppmB+2ppmLi DO : 8ppm . SCS14A SCS13A 10%.

9 SCC .. 400 1 SCC . 400 4 .. a SCS14A F8 b SUS316. SCC . 12 EBSD -TGSCC / - IGSCC / . 400 1 . 5 SCS14A F23, F15, F8 . 400 4 . Fe Ni Cr Si Mo Mn TG-SCC . F23 . F15 TG-SCC . F8 SCC . F23 . F15 F8 SCC . 169. 6, 2006 . 10 , , and , Corrosion, Vol. 63, No. 12, p. 1114 2007 . 11 , , and , Corrosion, Vol. 64, , 2008 . 12 . , , , , INSS. Journal, Vol. 16, pp. 127-135 2009 . 13 T. Yamada, T. Terachi, T. Miyamoto and K. Arioka, 14th Int. Conf. on Environmental Degradation of Materials in Nuclear Power Systems, Virginia Beach, VA, August 23-27, p. 684 2009 .. 14 T. Yamada, T. Terachi, T. Miyamoto and K. Arioka, Nuclear Plant Chemistry Conference 2010. 2004 . 15 , P . , , , INSS Journal 2000, 7, pp. 145-158 2000 . and , Effect of Deformation 16 T. Yamada, S. Okano, H. Kuwano: Journal of on SCC of unsensitized stainless steel, Nuclear Materials, 350, pp. 47-55. 2006 . Corrosion/2000, paper No.

10 203 2000 .. 17 . , , , , INSS. , and , Journal, Vol. 17, pp. 150-158 2010 . Effect of martensite and hydrogen on SCC of 18 ASTM E 399 90 Reapproved 1997 p. 2. stainless steel and alloy 600, Corrosion/2001, 19 K. Arioka, T. Yamada, and , Paper No. 01228 2001 .. Corrosion, Vol. 62, No. 1, pp. 74-83, 2006 . , Similarity of cold work and radiation hardening in enhancing yield strength and SCC growth of stainless steel in hot water, . Corrosion/2002, Paper No. 2509 2002 .. P . , , and , Stress corrosion crack growth rate behavior of various grades of cold worked stainless steel in high temperature water, Corrosion/2002, Paper No. 2511 2002 .. , , , Proc. of the 13th international conference on environmental degradation of materials in nuclear power systems, Whistler, British Columbia, 2007 .. R .Ishibashi, , , , and , Proceedings of the 52nd Japan Conference on Materials and Environments, 2005.