共查询到20条相似文献,搜索用时 46 毫秒
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MA Weidian Tsinghua University Beijing ChinaZHANG Shicheng TIAN Xitang Haribin Institute of Technology Harbin China Dept.of Mechanical Engineering Tsinghua University Beijing China 《金属学报(英文版)》1989,2(7):48-54
The effects of material inhomogeneity and weld width of the overmatched welded joints with alongitudinal crack or flaw upon the J-interal,a characterizing parameter for elastoplasticfracture,have been studied.The overmatched weld is idealized to be a parallelly cracked andsandwiched hard layer,the yieht stress of which is higher than that of the base metal.Numeri-cal solutions were obtained by using elastoplastic finite element method under the assumptionof plane stress.The resuits show that the values of J-integral are remarkably affected by thematerial inhomogeneity ant the weld width especially when the nominal stress or nominalstrain is comparatively high,which,therfore,should be taken into account when evaluatingthe crack driving force for an overmatched joint. 相似文献
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S. Ravi V. Balasubramanian S. Nemat Nasser 《Journal of Materials Engineering and Performance》2004,13(6):758-765
Welding of high-strength low-alloy (HSLA) steels involves the use of low-strength, equal-strength, and high-strength filler
materials (electrodes) compared with the parent material, depending on the application of the welded structures and the availability
of filler material. In the present investigation, the fatigue crack growth behavior of weld metal (WM) and the heat-affected
zone (HAZ) of undermatched (UM), equally matched (EM), and overmatched (OM) joints has been studied. The base material used
in this investigation is HSLA-80 steel of weldable grade. Shielded metal arc welding (SMAW) has been used to fabricate the
butt joints. A center-cracked tension (CCT) specimen has been used to evaluate the fatigue crack growth behavior of welded
joints, utilizing a servo-hydraulic-controlled fatigue-testing machine at constant amplitude loading (R=0). The effect of notch location on the fatigue crack growth behavior of strength mismatched HSLA steel weldments also has
been analyzed. 相似文献
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EffectsofstrengthmatchingandcrackdepthonthefractureparametersforweldedjointsTangWeiandShiYaowu(Xi'anJiaotongUniversity)Abstra... 相似文献
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H.Q.Zhang H.Y.Zhao Y.H.Zhang L.H.Li X.A.Zhang 《金属学报(英文版)》2004,17(4):584-590
Fatigue crack growth behaviors in electron beam weldments of a nickel-base superalloy are. studied. The objective of this paper is to discuss effects of the inhomogeneity of mechanical performance on fatigue crack growth (FCG) rate and crack path deviation (CPD). The base metal served in a turbine disk of aerospace engine was selected to fabricate bead-on-plate weldments by using electron beam welding. Some wedge-type opening loading specimens, notched in three different zone of weld metal, HAZ and base metal, were employed and performed fatigue crack growth tests at 650℃. The results show that the fatigue crack growth of electron beam welded joints is instable due to the influence of mechanical heterogeneities. Owing to the crack deviation at the weld metal and heat-affected-zone (HAZ), the effective growth driving force at the tip of fatigue crack was reduced with the reduction of the effective stress intensity factor (SIF) which finally causes fatigue crack rate decrease. Fatigue crack was strongly affected by size and the symmetrical characteristics of the plastic zone at the crack tip, which means that the integrity of the welded structure containing the fatigue crack mainly depended on the toughness of the low strenqth zone. 相似文献
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《Science & Technology of Welding & Joining》2013,18(2):252-258
AbstractThe use of high strength low alloy steels for high performance structures (e.g. pressure vessels and pipelines) requires high strength consumables to produce an overmatched welded joint. This globally overmatched multipass welded joint contains two significantly different microstructures, as-welded and reheated. In this paper, the influence of weld metal microstructure on fracture behaviour is estimated in comparison with the fracture behaviour of composite microstructures (as-welded and reheated). The lower bound of fracture toughness for different microstructures was evaluated by using the modified Weibull distribution. The results, obtained using specimens with crack front through the thickness, indicated low fracture toughness, caused by strength mismatching interaction along the crack front. In the case of through thickness specimens, at least one local brittle microstructure is incorporated in the process zone at the vicinity of the crack tip. Hence, unstable fracture occurred with small, or without, stable crack propagation. Despite the fact that the differences between the impact toughness of a weld metal and the that of base metal are insignificant, the fracture toughness of a weld metal can be significantly lower. 相似文献
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对十字接头分别进行恒辐轴向载荷和变载荷历程疲劳试验,接头疲劳裂纹通常开始发生在焊缝根部,但如果接头变形引起的弯曲应力较大,疲劳裂纹也可能发生在焊缝趾部。本研究试图找出影响焊接接头疲劳寿命各参数之间的相互关系,并利用作者引伸的焊接接头疲劳裂纹起始-扩展模型较精确地预测复杂焊件的疲劳寿命。该模型把疲劳裂纹起始寿命看成是疲劳裂纹萌生,早期生成并聚合成主疲劳裂纹的循环次数,利用应变控制疲劳数据和Palmg 相似文献
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Junchao An Hongyang Jing Guangchun Xiao Lei Zhao Lianyong Xu 《Journal of Materials Engineering and Performance》2011,20(8):1474-1480
Different regions of heat-affected zone (HAZ) were simulated by heat treatment to investigate the mechanisms of the Type IV
fracture of P92 (9Cr-2W) steel weldments. Creep deformation of simulated HAZ specimens with uniform microstructures was investigated
and compared with those of the base metal (BM) and the weld metal (WM) specimens. The results show that the creep strain rate
of the fine-grained HAZ (FGHAZ) is much higher than that of the BM, WM, the coarse-grained HAZ (CGHAZ), and the inter-critical
HAZ (ICHAZ). According to the metallurgical investigation of stress-rupture, the FGHAZ and the ICHAZ have the most severely
cavitated zones. During creep process, carbides become coarser, and form on grain boundaries again, leading to the deterioration
of creep property and the decline of creep strength. In addition, the crack grows along the FGHAZ adjacent to the BM in the
creep crack growth test (CCG) of HAZ. 相似文献
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J.Y. Huang R.F. Liu M.F. Chiang S.L. Jeng J.S. Huang R.C. Kuo J.C. Wang 《Corrosion Science》2011,(6):2289-2298
Corrosion fatigue behavior of the dissimilar metal weldment, Alloy 52-A508, under a simulated BWR coolant condition was studied. Corrosion fatigue crack growth rates of the dissimilar metal weldments were observed to increase with crack extension under the nominal constant ΔK loading mode. It could be accounted for by a decrease in the Cr and Ni contents and the crack closure effect with the weld depth. Finite element analysis on the welding residual stress was performed. The trend of analytical results agreed well with that of the residual stress measurements obtained by a hole-drilling strain gauge method. 相似文献
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0 IntroductionWhetherweldmetalsolidificationcrackoccursornotdependsonfollowingconditions[1,2]:theBrittleTemperatureRange(BTR)ofthematerial,itsductilityinBTR,thatis,materialresistancetothecrack,andthestrainintheBTR,thatis,themechanicaldrivingforceforthecrack.… 相似文献
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利用模拟焊接接头试样三点弯曲试验的方法,就焊接接头强度组配对其断裂性能的影响进行了研究。发现不同的焊接接头强度组配对其断裂韧性和裂纹扩展驱动力有不同程度的影响,在考虑强度组配对焊接接头的断裂性能的影响时,必须从材料的断裂韧性变化和裂纹扩展驱动力变化的两个方面来考虑。 相似文献