Please wait a minute...
金属学报  2017, Vol. 53 Issue (4): 455-464    DOI: 10.11900/0412.1961.2016.00462
  本期目录 | 过刊浏览 |
核电站316L不锈钢弯头应力腐蚀行为的寿命预测
郭舒,韩恩厚(),王海涛,张志明,王俭秋
中国科学院金属研究所中国科学院核用材料与安全评价重点实验室 沈阳 110016
Life Prediction for Stress Corrosion Behavior of 316L Stainless Steel Elbow of Nuclear Power Plant
Shu GUO,En-Hou HAN(),Haitao WANG,Zhiming ZHANG,Jianqiu WANG
Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
全文: PDF(3893 KB)   HTML
摘要: 

采用数值模拟方法对核电站316L不锈钢弯头的应力腐蚀裂纹扩展行为进行了研究。首先针对不锈钢厚壁弯头(外径355.6 mm,内径275.6 mm)进行有限元建模,在弯头内壁上创建出与实际裂纹相符的半椭圆状3D缺陷作为裂纹形状,其裂纹张开位移(δi)由Dugdale模型计算确定;然后根据有限元计算结果,建立裂纹应力强度因子 (K) 随裂纹深度 (a) 及附加应力 (P) 变化的拟合公式,结合实验数据得到管材在2种冷变形量下的应力腐蚀裂纹扩展速率(da/dt)拟合公式,利用迭代方法计算了裂纹穿透管壁所需的时间,为核电站安全评估提供了有效依据。研究显示,当弯头部位的冷变形量较小(硬度为230~245 HV)且在理想情况下 (无初始附加应力),弯头被应力腐蚀裂纹穿透耗时最长(约57 a);当初始附加应力增加至200 MPa,此失效时间约缩减至前者的1/5 (无应力释放)、2/7 (应力释放一半) 以及3/7 (应力完全释放);保持初始附加应力不变(200 MPa)并提高弯头部位冷加工变形量(由硬度为230~245 HV提高到275~300 HV),弯头的大变形部位被穿透时间约缩短至小变形部位失效时间的2/5 (无应力释放)、3/8 (应力释放一半) 以及1/3 (应力完全释放),由此可见应力释放程度的降低和冷加工变形量的增加均导致了核电站316L不锈钢弯头剩余寿命的缩短。

关键词 316L不锈钢弯头应力腐蚀裂纹扩展裂纹张开位移有限元分析应力释放冷加工变形    
Abstract

Stress corrosion cracking (SCC) is one of the main ageing mechanism in light water reactor (LWR). 316L austenitic stainless steel was adopted in nuclear industry for its relatively high corrosion resistance. The SCC of austenitic stainless steel may occur as it is subjected to both the tensile stress and the caustic medium, with regard to maintaining the structural integrity of components in nuclear power plant, an accurate prediction and efficient assessment of the component lifetime is significant and necessary. The stress corrosion crack propagation behavior of the 316L stainless steel elbow of nuclear power plant was investigated through a numerical simulation method. Firstly a finite element (FE) model was created for the stainless steel thick-walled elbow (the outer diameter is 355.6 mm, the inner diameter is 275.6 mm), with a semi-elliptical shaped 3D defect introduced at the internal surface of the elbow as the geometry of the crack, which was consistent with a practical crack, the crack opening displacement (δi) was determined by the calculations through the Dugdale model; subsequently, according to the FE calculation results, establish the fitting formula of the stress intensity factor (K) varying with the crack depth (a) and additional stress (P), and the fitting formula of the stress corrosion crack propagation rate (da/dt) for elbows under two types of cold work deformation was deduced through the combination with the experimental data, the crack propagation time was then calculated using a iterative method for cracks which evolved from different initial crack depth values to certain crack depth values. The calculation results provided effective reference criterion for the nuclear power plant safety assesment. This investigation demonstrated that, when the cold deformation extent of the elbow part is relatively small ( with the hardness of 230~245 HV) and it is under the ideal condition (no initial additional stress), it takes around 57 a for the stress corrosion crack to penetrate the elbow, when the initial additional stress was elevated to 200 MPa, the elbow failure time was shrinked to 1/5 (no stress release), 2/7 (half-stress release) and 3/7 (total stress release) of the former; keep the same initial additional stress (200 MPa) and increase the cold work deformation extent (the hardness was increased from 230~245 HV to 275~300 HV), the elbow failure time was shortened to 2/5 (no stress release), 3/8 (half-stress release) and 1/3 (total stress release) for the elbow part with higher cold deformation extent compared to the part with lower cold deformation extent, thus it was observed that both the decrease of the extent of stress relaxation and the increase of the extent of cold work deformation contributed to the reduction of the residual life of the nuclear power plant 316L stainless steel elbow.

Key words316L stainless steel elbow    stress corrosion crack propagation    crack opening displacement    finite element analysis    stress relaxation    cold work deformation
收稿日期: 2016-10-18      出版日期: 2017-01-20
基金资助:国家重点基础研究计划项目No.2011CB610500

引用本文:

郭舒,韩恩厚,王海涛,张志明,王俭秋. 核电站316L不锈钢弯头应力腐蚀行为的寿命预测[J]. 金属学报, 2017, 53(4): 455-464.
Shu GUO,En-Hou HAN,Haitao WANG,Zhiming ZHANG,Jianqiu WANG. Life Prediction for Stress Corrosion Behavior of 316L Stainless Steel Elbow of Nuclear Power Plant. Acta Metall Sin, 2017, 53(4): 455-464.

链接本文:

http://www.ams.org.cn/CN/10.11900/0412.1961.2016.00462      或      http://www.ams.org.cn/CN/Y2017/V53/I4/455

图1  裂纹几何形状示意图和弯头内壁上裂纹扩展示意图
图2  裂纹张开位移(δi)、裂尖张开位移(δ)和裂纹尖端塑性区尺寸(ry)示意图[11]
图3  网格划分示意图
图4  不锈钢316L弯头的真实应力-真实塑性应变曲线
图5  100 MPa附加应力下裂纹深度20 mm的弯头的应力分布
图6  不同深度裂纹在不同附加应力下裂纹张开位移的假设与计算值的对比
图7  不同附加应力下应力强度因子随裂纹深度的变化
SCC
test step
Small deformation (230~245 HV) Large deformation (275~300 HV)
K
MPam0.5
da/dt
10-7 mms-1
Duration
h
Δa
μm
K
MPam0.5
da/dt
10-7 mms-1
Duration
h
Δa
μm
1 20 1.40 256.1 98.5 20 4.28 536.8 699.0
2 25 1.84 216.8 149.0 25 4.83 519.0 921.0
3 30 2.24 232.0 192.0 33 5.97 144.9 313.0
4 40 2.65 195.1 189.8 40 7.42 498.1 1338.5
表1  应力腐蚀开裂实验不同阶段下316L不锈钢小变形和大变形部位的参数
图8  316L不锈钢弯头上硬度为230~245 HV部位的裂纹扩展时间随裂纹深度的变化曲线
图9  316L不锈钢弯头上硬度为275~300 HV部位的裂纹扩展时间随裂纹深度的变化曲线
[1] Han E-H, Wang J Q, Wu X Q, et al.Corrosion mechanisms of stainless steel and nickel base alloys in high temperature high pressure water[J]. Acta Metall. Sin., 2010, 46: 1379
[1] (韩恩厚, 王俭秋, 吴欣强等. 核电高温高压水中不锈钢和镍基合金的腐蚀机制[J]. 金属学报, 2010, 46: 1379)
[2] Pan P L, Zhong Y X, Ma Q X, et al.Development of manufacture technology for main pipe of large-sized nuclear power[J]. China Metal Form. Equip. Manuf. Technol., 2011, 46(1): 13
[2] (潘品李, 钟约先, 马庆贤等. 大型核电主管道制造技术的发展[J]. 锻压装备与制造技术, 2011, 46(1): 13)
[3] Li Y K, Lu S P, Li D Z, et al.Life prediction of welded joint in core shroud of BWR due to SCC failure[J]. Trans. China Weld. Inst., 2013, 34(9): 33
[3] (李永奎, 陆善平, 李殿中等. 核反应堆关键焊接结构应力腐蚀裂纹失效评估[J]. 焊接学报, 2013, 34(9): 33)
[4] Terachi T, Yamada T, Miyamoto T, et al.SCC growth behaviors of austenitic stainless steels in simulated PWR primary water[J]. J. Nucl. Mater., 2012, 426: 59
[5] Zhang L T, Wang J Q.Stress corrosion crack propagation behavior of domestic forged nuclear grade 316L stainless steel in high temperature and high pressure water[J]. Acta Metall. Sin., 2013, 49: 911
[5] (张利涛, 王俭秋. 国产锻造态核级管材316L不锈钢在高温高压水中的应力腐蚀裂纹扩展行为[J]. 金属学报, 2013, 49: 911)
[6] Huang Y Z, Titchmarsh J M.TEM investigation of intergranular stress corrosion cracking for 316 stainless steel in PWR environment[J]. Acta Mater., 2006, 54: 635
[7] Fujii T, Tohgo K, Kenmochi A, et al.Experimental and numerical investigation of stress corrosion cracking of sensitized type 304 stainless steel under high-temperature and high-purity water[J]. Corros. Sci., 2015, 97: 139
[8] Jivkov A P, Stevens N P C, Marrow T J. A two-dimensional mesoscale model for intergranular stress corrosion crack propagation[J]. Acta Mater., 2006, 54: 3493
[9] Wenman M R, Trethewey K R, Jarman S E, et al.A finite-element computational model of chloride-induced transgranular stress-corrosion cracking of austenitic stainless steel[J]. Acta Mater., 2008, 56: 4125
[10] Zhu X K, Joyce J A.Review of fracture toughness (G, K, J, CTOD, CTOA) testing and standardization[J]. Eng. Fract. Mech., 2012, 85: 1
[11] Werner K.The fatigue crack growth rate and crack opening displacement in 18G2A-steel under tension[J]. Int. J. Fatigue, 2012, 39: 25
[12] Chen X D, Chen X Z, Cui H X.Analysis of elastic-plastic stress on surge-line nozzle of RCS in Qinshan phase II NPP project[J]. Nucl. Pow. Eng., 2003, 24(S1): 122
[12] (陈学德, 陈晓舟, 崔赪昕. 秦山核电二期工程反应堆主冷却剂管道系统辅助接管嘴的弹塑性分析[J]. 核动力工程, 2003, 24(S1): 122)
[13] Chen A J, Xu C, Hu X Q.Several methods for calculating stress intensity factors of thick walled cylinder with cracks[J]. J. Nanjing Univ. Sci. Technol., 2002, 26: 430
[13] (陈爱军, 徐诚, 胡小秋. 带裂纹厚壁圆筒应力强度因子的几种计算方法[J]. 南京理工大学学报, 2002, 26: 430)
[14] Galvele J R.1999 W.R. Whitney Award Lecture: Past, present, and future of stress corrosion cracking[J]. Corrosion, 1999, 55: 723
[15] Gutman E M.An inconsistency in "film rupture model" of stress corrosion cracking[J]. Corros. Sci., 2007, 49: 2289
[16] Scully J C.The Theory of Stress Corrosion Cracking in Alloys[M]. Brussels: NATO, 1971: 21
[17] Chu W Y.Hydrogen Damage and Delayed Fracture [M]. Beijing: Metallurgical Industry Press, 1988: 1
[17] (褚武扬. 氢损伤和滞后断裂 [M]. 北京: 冶金工业出版社, 1988: 1)
[18] Xiao J M.Metallic Corrosion under Stress [M]. Beijing: Chemical Industry Press, 1990: 1
[18] (肖纪美. 应力作用下的金属腐蚀 [M]. 北京: 化学工业出版社, 1990: 1)
[19] Chu W Y.Latest progress in hydrogen induced cracking and stress corrosion cracking[J]. Prog. Nat. Sci., 1991, (5): 393
[19] (褚武扬. 氢致开裂和应力腐蚀机理新进展[J]. 自然科学进展, 1991, (5): 393)
[20] Hou X Z, Zheng W J, Song Z G, et al.Effect of cold work on structure and mechanical behavior of 316L stainless steel[J]. J. Iron Steel Res., 2013, 25(7): 53
[20] (侯小振, 郑文杰, 宋志刚等. 冷加工对316L不锈钢力学行为和组织的影响[J]. 钢铁研究学报, 2013, 25(7): 53)
[21] Song R B, Xiang J Y, Hou D P.Microstructure characteristics and work-hardening mechanism of 316L austenitic stainless steel during cold deformation[J]. J. Univ. Sci. Technol. Beijing, 2013, 35: 55
[21] (宋仁伯, 项建英, 侯东坡. 316L不锈钢冷变形加工硬化机制及组织特征[J]. 北京科技大学学报, 2013, 35: 55)
[22] Sui S H, Song T G, Sui L H.Effect of deformation on semi-solid structure evolution of LC9 aluminum alloy[J]. Foundry, 2006, 55: 683
[22] (隋少华, 宋天革, 隋鲁华. 冷变形对LC9铝合金等温转变半固态组织的影响[J]. 铸造, 2006, 55: 683)
[23] He D F, Wang J Y.Cold work-caused detriment of corrosion resistance of stainless steel tube and preventative controls[J]. Steel Pipe, 2015, 44: 1
[23] (何德孚, 王晶滢. 冷加工对不锈钢钢管耐蚀性的损害及其控制[J]. 钢管, 2015, 44: 1)
[24] Xu C C, Zhang X S, Hu G.Microstructure change of AISI304 stainless steel in the course of cold working[J]. J. Beijing Univ. Chem. Technol., 2002, 29(6): 27
[24] (许淳淳, 张新生, 胡钢. AISI304不锈钢在冷加工过程中的微观组织变化[J]. 北京化工大学学报, 2002, 29(6): 27)
[25] Ghosh S, Kain V.Effect of surface machining and cold working on the ambient temperature chloride stress corrosion cracking susceptibility of AISI 304L stainless steel[J]. Mater. Sci. Eng., 2010, A527: 679
[26] García C, Martín F, De Tiedra P, et al.Effects of prior cold work and sensitization heat treatment on chloride stress corrosion cracking in type 304 stainless steels[J]. Corros. Sci., 2001, 43: 1519
[27] Sáez-Maderuelo A, Gómez-Brice?o D.Stress corrosion cracking behavior of annealed and cold worked 316L stainless steel in supercritical water[J]. Nucl. Eng. Des., 2016, 307: 30
[1] 张利涛,王俭秋. 国产锻造态核级管材316L不锈钢在高温高压水中的应力腐蚀裂纹扩展行为[J]. 金属学报, 2013, 49(8): 911-916.
[2] 张姝,田素贵,于慧臣,于莉丽,于兴福. [111]取向镍基单晶合金在蠕变期间组织演化的有限元分析[J]. 金属学报, 2012, 48(5): 561-568.
[3] 许恒栋 赵海燕 S¨orn Ocylok Igor Kelbassa. 低碳钢表面激光直接镀Ti层中裂纹形成的研究[J]. 金属学报, 2012, 48(2): 142-147.
[4] 方臣富 陈志伟 胥国祥 胡庆贤 周航宇 时振. 缆式焊丝CO2气体保护焊工艺研究[J]. 金属学报, 2012, 48(11): 1299-1305.
[5] 张姝 田素贵 于慧臣 苏勇 于兴福 于莉丽. [011]取向镍基单晶合金在拉伸蠕变期间的组织演化与有限元分析[J]. 金属学报, 2011, 47(1): 61-68.
[6] 郎文昌 肖金泉 宫骏 孙超 黄荣芳 闻立时. 轴对称磁场对电弧离子镀弧斑运动的影响[J]. 金属学报, 2010, 46(3): 372-379.
[7] 崔 航 陈怀宁 陈 静 黄春玲 吴昌忠. 球形压痕法评价材料屈服强度和应变硬化指数的有限元分析[J]. 金属学报, 2009, 45(2): 189-194.
[8] 龚明明; 谭丽丽; 耿芳; 杨柯 . 新型多孔镁压缩性能的有限元分析[J]. 金属学报, 2008, 44(2): 237-242 .
[9] 徐娜; 宗亚平; 张芳; 左良 . SiCp/Al-2618复合材料的应力-应变曲线和增强颗粒受力的模拟[J]. 金属学报, 2007, 43(8): 863-867 .
[10] 武传松; 张明贤 . DE-GMAW高速电弧焊工艺机理的研究[J]. 金属学报, 2007, 43(6): 663-667 .
[11] 张洪武; 张昭; 陈金涛 . 搅拌摩擦焊接过程中搅拌头转速对材料流动的影响[J]. 金属学报, 2005, 41(8): 853-859 .
[12] 丁向东; 刘刚; 王瑞红; 孙军; 江中浩; 连建设 . 颗粒增强金属基复合材料的屈服行为[J]. 金属学报, 2002, 38(4): 369-375 .
[13] 李寰;李家宝;孙立志;王中光. 低温处理对SiC_p/6061Al复合材料残余应力的影响[J]. 金属学报, 1996, 32(12): 1279-1284.
[14] 黄正;姚枚. 解理裂缝过界扩展模型[J]. 金属学报, 1990, 26(1): 53-57.