X80钢补焊残余应力影响下的氢扩散模拟
Hydrogen Diffusion Simulation of X80 Steel under Residual Stress of Repair Welding
- 2023年53卷第6期 页码:83-91
DOI: 10.7512/j.issn.1001-2303.2023.06.13
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通过有限元软件ABAQUS建立了X80钢三维补焊模型,综合考虑焊接残余应力和组织不均匀性的影响,采用顺序间接耦合方法,对平板补焊的温度场、应力场和氢扩散进行耦合计算。研究了在不同补焊热输入条件下的补焊残余应力变化规律。结果表明:补焊后最大残余应力出现在补焊焊缝区域,横向残余应力S11应力峰值增加55%,纵向残余应力S22超过材料屈服强度。不同补焊热输入对S11影响较大。无残余应力影响时氢扩散呈现梯度分布,有应力影响时,氢在残余应力集中区域浓度较大,残余应力促进了氢的扩散和聚集。
A three-dimensional repair welding model of X80 steel was established by using the finite element software ABAQUS. Considering the influence of welding residual stress and microstructure inhomogeneity, the temperature field, stress field and hydrogen diffusion of plate repair welding were coupled by using the sequential indirect coupling method. The variation of residual stress in repair welding under different heat input conditions was studied. The results show that the maximum residual stress after repair welding occurs in the weld zone, the peak stress of transverse residual stress S11 increases by 55%, and the longitudinal residual stress S22 exceeds the yield strength of the material. The S11 is greatly affected by different heat input of repair welding. When there is no residual stress, hydrogen diffusion presents a gradient distribution. When there is stress, hydrogen concentration is large in the residual stress concentration area, and the residual stress promotes the diffusion and enrichment of hydrogen.
X80 steel;
repair welding;
residual stress;
hydrogen diffusion
目前油气输送管线向着远距离、高输送压力、大口径趋势发展,X80管线钢因输送效率、铺设费用、结构强度等因素正逐渐取代X70钢,成为高压油气输送管线的主流钢种[
近年来,越来越多的学者采用数值模拟方法研究焊接残余应力及氢扩散行为。P. Dong等[
本文以X80钢平板补焊焊接接头为研究对象,采用ABAQUS建立数值模拟模型,分析补焊前后不同补焊热输入条件下的残余应力变化规律。以残余应力场为氢扩散分析的预定义场,考虑残余应力和焊接接头组织不均匀性的影响,探讨氢的扩散和聚集行为。
对2块尺寸为200 mm×200 mm×22 mm的X80钢板进行平板对接焊。如
图1 补焊几何模型
Fig.1 Geometrical model of repair welding
补焊在热影响区,焊道为1道,尺寸为80 mm×
8 mm×3 mm。
采用不均匀的网格划分方法,如
图2 网格划分及约束条件
Fig.2 Mesh division and constraint conditions
对于残余应力诱导氢扩散的数值模拟过程分为三步:①对补焊有限元模型进行温度场的计算;②将温度场结果导入焊接残余应力分析中进行耦合计算;③将焊接残余应力场作为应力诱导氢扩散的预定义场进行顺次耦合计算。本文初始焊之后的补焊是通过ABAQUS中的“生死单元”技术来实现,即先将补焊区域单元“杀死”,去除其应力但保留其他单元应力,然后通过“生成”模拟补焊金属并施加双椭球热源,进行补焊模拟。
由于焊接的高温作用,需要考虑材料性能参数随温度变化的情况。假设焊缝与母材材料相同。X80钢性能参数随温度变化如
图3 X80钢材料性能参数
Fig.3 Material performance parameters of X80 steel
在计算残余应力诱导氢扩散的分析中,母材、焊缝及热影响区的氢扩散参数采用
区域 | 扩散系数D /(10-6 cm2·s-1) | 浓度C0 /(10-6) | 溶解度S /(10-11 Pa-1/2) |
---|---|---|---|
母材 | 3.302 | 0.023 50 | 4.797 |
焊缝 | 5.315 | 0.016 65 | 3.399 |
热影响区 | 4.138 | 0.020 10 | 4.103 |
考虑焊接残余应力诱导氢扩散的影响,应力梯度系数计算方法为:
Kσ=CSVHR(T-θZ) | (1) |
式中 Kσ为应力梯度系数,单位:N/m1/2;VH为氢原子在钢中的偏摩尔体积,取值为2.0 cm3/mol;R为气体常数,通常取8.314 J/(mol·K);T为温度,单位:℃;θ z为绝对零度,-273.15 ℃。
焊道 | 电压/V | 电流/A | 焊接速度/(mm·s-1) |
---|---|---|---|
根焊1 | 22 | 110 | 2 |
填充2~6 | 23 | 130 | 2.5 |
盖面7 | 23 | 120 | 2.2 |
补焊热输入/(kJ·cm-1) | 电压/V | 电流/A | 焊接速度/(mm·s-1) |
---|---|---|---|
11 | 23 | 120 | 2 |
14 | 24 | 150 | 2 |
17 | 25 | 170 | 2 |
在焊接温度场中,焊件初始温度设为20 ℃,模型外表面为对流换热和热辐射的边界条件,对流换热系数取10 W/(m2·℃),辐射率取0.85。
应力场模拟计算时,为了防止板材发生刚性位移,采用如
在氢扩散分析中,表征边界条件的参数是氢活度∅,其计算方法为:
∅=CS | (2) |
式中 ∅为氢活度,单位:atm1/2;C为氢浓度,单位:ppm;S为氢溶解度,单位:ppm/atm1/2。
由于在焊接过程中氢的引入主要来源于焊缝处,因此通过设置模型焊缝处的氢活度∅来实现氢的引入[
为验证焊接模型数值模拟的正确性,以葛华等[
图4 有限元模拟与试验结果对比
Fig.4 Comparison of FEA and test results
为更好地观察焊后残余应力的分布情况,从模型上取2条路径(见
以补焊热输入为11 kJ/cm为例,对补焊前后的残余应力进行分析。
图5 补焊前后Mises应力云图
Fig.5 Mises stress contour before and after repair welding
图6 补焊前后S11应力云图
Fig.6 S11 stress contour before and after repair welding
图7 补焊前后S22应力云图
Fig.7 S22 stress contour before and after repair welding
提取路径1、2的残余应力值绘成曲线图做进一步分析,
图8 沿路径1、2处Mises残余应力
Fig.8 Mises residual stress along path1 and path 2
图9 沿路径1、2处S11残余应力
Fig.9 S11 residual stress along path1 and path 2
图10 沿路径1、2处S22残余应力
Fig.10 S22 residual stress along path1 and path 2
应力变化基本相同;沿路径2处,初始焊S11应力峰值位于焊趾处,最大值为335.33 MPa,补焊后应力峰值转移到补焊焊趾部位,最大值为521.91 MPa,增加了186.58 MPa,增幅55.64%。而在初始焊和补焊中心区域的S11应力均为最低,使得应力变化趋势近似“M”形。纵向残余应力S22在路径1处,初始焊影响较小,补焊后S22应力峰值达到524.14 MPa;路径2处初始焊S22应力峰值为574.13 MPa,补焊后达到662.50 MPa,增加了88.37 MPa,已超过材料屈服强度(590 MPa)。
建立补焊热输入为11 kJ/cm、14 kJ/cm、17 kJ/cm的补焊有限元模型,
图11 沿路径1、2处Mises残余应力
Fig.11 Mises residual stress along path1 and path 2
图12 沿路径1、2处S11残余应力
Fig.12 S11 residual stress along path1 and path 2
图13 沿路径1、2处S22残余应力
Fig.13 S22 residual stress along path1 and path 2
在无残余应力诱导时,氢的扩散主靠浓度梯度来实现。本文在焊缝处引入氢浓度作为初始条件,而平板边界处氢浓度为零,这样的浓度差将促使氢从焊缝中心向两边自由扩散,扩散时间设为1 000 h。
图14 氢浓度分布云图
Fig.14 Contour of hydrogen concentration distribution
图15 沿路径2的氢浓度分布
Fig.15 Curve of hydrogen concentration distribution along path 2
在氢扩散的分析中,静水应力σh影响着氢浓度的分布,其值为三向主应力:横向应力S11、纵向应力S22、径向应力S33的平均值。
图16 沿路径1、2处静水应力及氢浓度分布
Fig.16 Hydrostatic stress and hydrogen concentration distribution along path 1 and path 2
由
图17 沿路径1、2有无残余应力影响下氢浓度分布
Fig.17 Hydrogen concentration distribution along path 1 and path 2 with and without residual stress
(1)X80钢在初始焊接后,焊缝中心处残余应力值较大,补焊后最大残余应力出现在焊缝补焊区域,横向和纵向残余应力均有所增加,由于热源的加热作用,在邻近补焊区两端残余应力得到了部分释放。
(2)不同补焊热输入条件下,Mises残余应力峰值变化不大。随着补焊热输入的增大,横向残余应力S11沿路径1处逐渐减小,沿路径2处在热影响区有小幅度增加,而纵向残余应力S22在补焊区及热影响区均无明显变化。
(3)无残余应力影响时,氢浓度在纵向区域均匀分布,横向氢扩散呈现递减趋势。有残余应力诱导下,氢在静水应力集中区富集,其扩散规律与静水应力变化基本一致,焊接残余应力促进了氢的扩散和聚集。
隋永莉. 国产X80管线钢焊接技术研究[D].天津:天津大学,2008. [百度学术]
SUI Y L. Welding technology research for girth of domestic X80 grade line pipe[D]. Tianjin:Tianjin University,2008. [百度学术]
Freimanis A J,Segall A E,Conway J C. The Influence of Temperature on the Wear Mode and Deterioration of Coatings Used For Titanium Aircraft Engine Components[J]. Tribology Transactions,2002,45(2):193-198. [百度学术]
朱王晶,郭建章,张海兵,等. 氢在金属中的扩散[J].热加工工艺,2013,42(24):26-31. [百度学术]
ZHU W J,GUO J Z,ZHANG H B,et al. Diffusion of hydrogen in metal[J]. Hot Working Technology,2013,42(24):26-31. [百度学术]
Dong P,Zhang J,Bouchard P J. Effects of Repair Weld Length on Residual Stress Distribution[J]. Journal of Pressure Vessel Technology,2002,124(1):74-80. [百度学术]
沈利民,巩建鸣,余正刚,等. Q345R钢焊接接头不同部位补焊残余应力的有限元分析[J]. 焊接学报, 2009,30(9):57-60,64. [百度学术]
SHEN L M,GONG J M,YU Z G,et al. Residual stress analysis of repair welding at different zone of Q345R welded joint based on finite element simulation[J].Transactions of The China Welding Institution,2009,30(9):57-60,64. [百度学术]
蒋文春,巩建鸣,唐建群,等. 焊接残余应力下氢扩散的数值模拟[J]. 焊接学报,2006,27(11):57-60,64. [百度学术]
JIANG W C,GONG J M,TANG J Q,et al. Numerical simulation of hydrogen diffusion under welding residual stress[J]. Transactions of The China Welding Institution,2006,27(11):57-60,64. [百度学术]
Zhao W,Yang M,Zhang T,et al. Study on hydrogen enrichment in X80 steel spiral welded pipe[J]. Corrosion Science,2018,133(2):251-260. [百度学术]
严春妍,张根元,刘翠英. X80管线钢焊接接头氢分布的数值模拟[J]. 焊接学报,2015,36(9):103-107. [百度学术]
YAN C Y,ZHANG G Y,LIU C Y. Numerical simulation of hydrogen distribution in welded joint of X80 pipeline steel[J]. Transactions of The China Welding Institution,2015,36(9):103-107. [百度学术]
张体明,赵卫民,蒋伟,等. X80钢焊接残余应力耦合接头组织不均匀下氢扩散的数值模拟[J]. 金属学报,2019,55(2):258-266. [百度学术]
ZHANG T M,ZHAO W M,JIANG W,et al. Numerical simulation of hydrogen diffusion in X80 welded joint under the combined effect of residual stress and microstructure inhomogeneity[J]. Acta Metallurgica Sinica,2019,55(2):258-266. [百度学术]
元媛,严春妍,安爱玲,等. X80管线钢平板多层对接焊数值模拟[J]. 电焊机,2017,47(5):98-103. [百度学术]
YUAN Y,YAN C Y,AN A L,et al. Numerical simulation of multi-layer butt-welding of X80 pipeline steel[J]. Electri Welding Machine,2017,47(5)98-103. [百度学术]
王凯,赵建平. 补焊工艺对含夹杂结构界面损伤的影响[J]. 压力容器,2021,38(2):22-27. [百度学术]
WANG K,ZHAO J P. Influence of repair welding technology on interface damage of structures containing inclusions[J]. Pressure Vessel Technology,2021,38(2):22-27. [百度学术]
贾倩倩. 焊接残余应力对典型焊接接头氢扩散的影响研究[D]. 江苏:江苏科技大学,2020. [百度学术]
JIA Q Q. Study of the influence of residual stress on hydrogen diffusion of typical welded joints[D].Jiangsu:Jiangsu University of Science and Technology,2020. [百度学术]
葛华,黄海滨,蒋毅,等. X80管道环缝焊接残余应力数值模拟[J]. 焊接,2021,(12):17-23. [百度学术]
GE H,HUANG H B,JIANG Y,et al. Numerical simulation of residual stress in circumferential weld of X80 pipeline[J]. Welding & Joining,2021,(12):17-23. [百度学术]
Keivani R,Jahazi M,Pham T, et al. Predicting residual stresses and distortion during multisequence welding of large size structures using FEM[J]. International Journal of Advanced Manufacturing Technology,2014,73(1-4):409-419. [百度学术]
刘亚良,杨鑫华. 补焊位置对S355J2W对接接头残余应力分布影响[J]. 辽宁工程技术大学学报(自然科学版),2016,35(11):1290-1294. [百度学术]
LIU Y L,YANG X H. Numerical simulation of effects of different repair welding zone on S355J2W butt joint welding residual stress distribution[J]. Journal of Liaoning Technical University(Natural Science),2016,35(11):1290-1294. [百度学术]
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