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排序方式: 共有267条查询结果,搜索用时 31 毫秒
1.
孙咸 《焊管》2022,45(5):22-35
综述了铁素体与铁素体异种金属焊缝(dissimilar metal welds,DMWs)接头界面组织及其影响。结果表明,在焊后热处理或运行温度下的铁素体钢DMWs接头的不均匀界面组织中,通常会形成脱碳层和增碳层。在铁素体钢DMWs焊接接头界面组织影响因素中,焊缝金属的化学成分有重要影响;焊后热处理规范(温度和时间)、工作温度下运行时间的影响较为突出;焊接工艺参数的影响亦不可忽略。异种钢接头界面处近缝区裂纹的产生,以及接头的蠕变强度随Larson Miller 参数增大而下降等不利影响,均为异种钢界面碳迁移行为所导致。焊缝成分控制法是接头界面组织控制或改善的必要条件,而脱碳层部位转移法能有效防止裂纹发生,亦是接头安全运行的重要工艺措施之一。  相似文献   
2.
Residual Stress Evolution in Repair Welds   总被引:1,自引:0,他引:1  
C. Veiga  A. Loureiro  A. Dias 《Strain》2003,39(2):57-63
Abstract: The aim of this paper is to study the influence of the repair procedure on the evolution of residual stress distribution in butt welds. C-Mn steel coupon plates of 11 mm thickness were prepared, subjected to stress relief heat treatment and welded with two beads, using the gas metal arc welding process. After the deposition of two weld beads, two successive repair welds were made on the middle length of the second bead. Longitudinal and transverse residual stresses were measured in the vicinity of the weld, after deposition of the two weld beads and after each repair weld. Residual stress evaluation was conducted using an X-ray diffraction method. The repair welds caused a decrease in magnitude of the initial longitudinal residual welding stresses, and an increase of the transverse residual stress magnitude, in tension at points within the repair length, and in compression at points outside the repair length.  相似文献   
3.
戴庭本 《大氮肥》1994,17(2):125-126
尿素高压热交换器役前检查必要性金陵石化公司化肥厂戴庭本EssentialityofPreservicingInespectionofUreaHPHeatExchangers¥Thearticleanalyzestheeffectofthequalit...  相似文献   
4.
Thermodynamicanalysisofinclusioninweld¥ZhangXiaochengandZhangWeiping(SouthChinaUniversityofTechnology.Gaungzhou)Abstract:Them...  相似文献   
5.
Base metals of domestic pipeline steels were used to study the effect of Mn on corrosion properties of SSCC( Sulfide Stress Corrosion Cracking), and welds were carried out to study the effect of MnS on corrosion properties of HIC ( Hydrogen Induced Cracking) both in solutions with wet hydrogen sulfide ( H2 S ). They were respectively conducted by referring to the standards of SSCC and HIC. Testing results revealed that with the increase of content Mn, the resistance of SSCC will be decreased, from the point of metallurgic view, and it is Mn element not C element to lead to the testing results of SSCC. Meanwhile, even under the condition without inclusions MnS, HIC in welds still occurred. That is to say, MnS is not necessary for HIC, the presence of local banded structures in which Mn and P are inclined to aggregate cause to the phenomena of HIC.  相似文献   
6.
刘炀 《铸造技术》2004,25(12):955-956
对应用二氧化碳气体保护焊处理铸造缺陷现场操作中极易出现的问题 ,提出预防措施。实践证明 :在电流电压满足U =0 .0 4I 2 0± 2 ,CO2 气体流量选取 2 0mL/min ,焊丝干伸长度取L =10D(D为焊丝直径 ) ,焊接运丝速度保持 3 0~ 60mm/min时 ,可确保焊补度量。并对保护补焊过程出现的气孔缺陷提出了应对措施  相似文献   
7.
AZ80 hollow profile was produced by porthole-die extrusion. The mechanical behavior and microstructure characteristic of extrusion welds in AZ80 hollow profile during different T5 heat treatments were investigated. Five kinds of morphologies of β-Mg17Al12 were observed in turn in weld regions under various temperatures. Extrusion weld is not weakest region in AZ80 hollow profile in terms of hardness, the peak hardness of weld regions is roughly equal to the weld-free regions at different aging temperatures, which is attributed to similar volume fraction, morphology, and size of β-Mg17Al12 precipitate in weld regions and weld-free regions. The precipitate-free zones (PFZs) usually form near the welds interface in aging process, and the hardness of PFZs is usually lower than those of weld regions and weld-free regions. Aging at 200°C for 24?h is suitable heat treatment system for AZ80 hollow profile, which can achieve excellent mechanical property and simultaneously reduce the width of PFZs.  相似文献   
8.
工况下运行的异种钢接头易沿焊缝界面开裂而发生早期失效.本文对小直径钢102/Inconel82/TP347H异种钢管、不同坡口角度与不同热处理制度下接头中的焊接残余应力进行了实测,结果表明对适用于现场焊接且可延长接头寿命的改进型坡口并不会增大焊接应力,提出在工况温度下接头中的焊接应力并不能很快衰减、焊后热处理可显著地降低该种异种钢接头中焊接应力的观点.  相似文献   
9.
Abstract

The influence of R ratio in the range 0·05–0·4 on the ambient temperature fatigue crack growth behaviour of an austenitic stainless steel weld, SS 316(N), has been studied. Results indicate that the cyclic threshold stress intensity factor ΔKth increases with decreasing R ratio. The data are compared with those for SS 316, SS 316L and SS 316L(N) base materials from the literature, and various approaches dealing with the R ratio effects are examined. Zhang’s model considering the contribution of the crack tip plasticity to the fundamental fatigue crack propagation process does provide a consistent interpretation for the data.  相似文献   
10.
Shipbuilding in blocks, as being usual on all larger shipyards, requires that the blocks will finally be welded together manually or semi‐automatically, that is, with butt‐welds in transverse direction that have to withstand relatively high dynamical loads. Modern shipbuilding aims at lightweight construction with thin plates that may have a plate thickness down to 4 mm. Previous investigations showed that manually produced butt‐welds in such thin structures did not reach the calculated fatigue life as required in the rules. Up to the present, this problem has not yet been solved, and it is questioned if all influence factors on the fatigue behaviour of real structures are correctly considered as no damage cases at butt joints that are known yet. In the investigation described here, results from small‐scale specimens tested with cyclic loads will be transferred to large components, considering the effects of recorded pre‐deformations induced by welding as well as measured differences in residual stresses between small‐scale specimens and large components, thus clarifying how far for instance a detrimental stress ratio should be taken into account by the rules for thin plates.  相似文献   
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