超级奥氏体不锈钢904犔焊接裂纹渗透检测及成因分析

采用液体渗透检测ⅡC-d(溶剂悬浮显像剂),有效检测超级奥氏体不锈钢904L在焊接过程中产生的焊接裂纹,返修时采用同样方法检测缺陷的去除,保证了焊接质量.同时对焊接裂纹的产生原因进行粗浅分析.     

超级奥氏体不锈钢904L焊接裂纹渗透检测及成因分析

采用液体渗透检测ⅡC-d（溶剂悬浮显像剂）,有效检测超级奥氏体不锈钢904L在焊接过程中产生的焊接裂纹,返修时采用同样方法检测缺陷的去除,保证了焊接质量。同时对焊接裂纹的产生原因进行粗浅分析。     

奥氏体不锈钢焊接裂纹的射线及渗透检测方法

阐述了在压力容器制造过程中,针对奥氏体不锈钢产生的焊接裂纹,运用射线检测和着色渗透检测两种方法进行检测,对其表示形式、产生部位、性质、大小、可能的产生原因进行分析,得出奥氏体不锈钢焊接裂纹在不同检测方法的表现特征。说明这两种检测方法的结合在奥氏体不锈钢焊接裂纹的检测工作中是一种非常有效的措施。     

X12CrNiSi1636奥氏体耐热不锈钢焊接新工艺

对X12CrNiSi1636奥氏体耐热不锈钢在焊接生产过程中极易产生热裂纹的现象进行了深入研究．提出采用变电流焊接、有效控制层间温度以度减小线能量进行焊接的新工艺。并成功应用于生产实践。     

奥氏体不锈钢焊接热裂纹的成因及防止对策

分析了奥氏体不锈钢焊接过程中产生热裂纹的原因,提出了针对性的防止对策。     

焊接单相奥氏体不锈钢时如何防止产生热裂纹

单相奥氏体不锈钢如0Cr25Ni2O焊接时的热裂纹倾向比1Cr18Ni9Ti不锈钢要大得多，特别是在根部打底焊道以及弧坑处最易产生热裂纹。但是这类钢不能依靠加入少量铁素体来提高抗裂性。因为要在焊缝中形成铁素体，势必加入大量铁素体形成元素，这就使焊缝的成分和性能比母材相差太大，以致不能满足接头的使用要求。此外，更多的铁素体还会使接头脆化。     

不锈钢管道对接焊缝焊接热裂纹超声波检测技术

由于安装制造工艺的原因,核电站辅助系统奥氏体不锈钢对接焊缝极易产生焊接热裂纹,此类热裂纹具有长度短、高度小、多集中于焊缝表面和近表面区域等特征,同时又由于奥氏体材料自身的影响,依据标准采用的体积性检测方法不能获得较好的检测效果。笔者针对特定对象,介绍了核辅助系统奥氏体不锈钢对接焊缝焊接热裂纹超声波检测技术及验证结果,为此类焊接热裂纹检测技术提供了参考。     

奥氏体不锈钢管道焊接热裂纹缺陷模拟方法

基于笔者先期对服役奥氏体不锈钢管道对接接头热裂纹缺陷特性的研究结论,对具有一定程度热裂倾向的焊条配制、试验设计、热裂纹缺陷在焊接试件中的预制及热裂纹的检验和验证等方面进行了系统性研究,论述了奥氏体不锈钢管道对接接头热裂纹缺陷的模拟方法.     

不锈钢复合板焊接裂纹的返修

我厂在焊接复合板材质 2 0Ｒ +0 0Ｃｒ17Ｎｉ14Ｍｏ2(板厚 16ｍｍ +3ｍｍ)时 ,因供货质量原因 ,在焊接时焊缝区及相邻母材 15 0ｍｍ× 10 0ｍｍ范围内出现了大量裂纹 ,有些裂纹是贯穿性的 ,因此针对这一缺陷制定了返修工艺。1　焊接材料在焊接过渡层时 ,基层的碳钢与复层奥氏体钢焊接 ,由于基层成分 (2 0Ｒ)对焊缝金属有的稀释作用 ,使焊缝中奥氏体元素含量降低 ,若焊缝中出现马氏体组织 ,会恶化接头性能 ,甚至产生裂纹 ,因此过渡层焊材选用至关重要 ,18- 8型焊接材料不能满足要求 ,2 5 -2 0型焊接材料焊接后又可能因属于单相奥氏体组织而产…     

奥氏体不锈钢焊缝金属的电化学腐蚀性能

采用PASTAT30型恒电位仪测试了SUS 316奥氏体不锈钢钨极氩弧焊TIG,熔化极氩弧焊MIG和钨极氩弧焊加填丝TIG M焊缝金属的电化学腐蚀性能.结果表明,在质量分数9.8%H2SO4溶液中,母材及焊缝的抗电化学腐蚀能力由大到小的顺序为母材＞TIG M焊缝＞MIG焊缝＞TIG焊缝,在质量分数5.0%HCl溶液中为母材＞MIG焊缝＞TIG M焊缝＞TIG焊缝,由此可知TIG焊缝金属的抗腐蚀能力最弱.由Tafel曲线可知,SUS316奥氏体不锈钢在H2SO4溶液中的钝化区间较长,在HCl溶液中的钝化区间很短暂,所以不锈钢在盐酸溶液比硫酸溶液中抗腐蚀性能差.晶间腐蚀试验结果与9.8%H2SO4溶液中电化学腐蚀试验结果相同.     

锻造奥氏体不锈钢管道焊缝的单侧超声检测

针对AP1000机组役前检查发现的锻造奥氏体不锈钢管道环焊缝轴向只能进行单侧扫查的问题,在调研的基础上,对选取的有代表性的试块和缺陷进行了超声检测和定量分析,提出了解决意见。     

Effect of sulfur and oxygen on weld penetration of high-purity austenitic stainless steels

Convective flow during arc welding depends upon the surface tension gradient (dy/dT, Marangoni flow), buoyancy, arc drag force, electromagnetic force, shielding gas, and the viscosity of the melt. The Marangoni and the buoyancy-driven flow are the major factors in controlling weld penetration in ferrous alloys, especially austenitic stainless steels such as 304 and 316. Small variations in the concentration of surfactants, such as sulfur and oxygen, in stainless steels cause significant changes in the weld penetration and depth/width (D/W) ratio of the fusion zone. Gas-tungsten arc (GTA) welds were done on low- and high-sulfur 304 and 316 heats using pure argon and argon/oxygen shielding gases. Also, laser beam (LB) welds were done on the 304 and 316 heats using pure argon as the shielding gas. Increase in the sulfur content decreased the D/W ratio for the GTA 304 welds using pure argon, but for the case of LB 304 welds the results were the opposite. For the GTA 316 welds and LB 316 welds, increase in sulfur increased the D/W ratio of the fusion zone. Oxygen increased the D/W ratio of both the 304 and 316 GTA welds.     

Mechanical behavior of austenitic stainless steel weld metals with microfissures

Mechanical behavior of all-weld-metal specimens of 308L and 316L weld with and without microfissures was evaluated by standard and pre-strain tensile testing. The test results show a similar yield strength, and a small difference on tensile strength for fissured and fissure-free 316L weld deposits. There is virtually no effect on yield and tensile strength for 308L. Microfissures in these weld metals negatively affect ductility of 316L and 308L.     

Ultrasonic inspection for circumferential butt joint of austenitic stainless steel with carbon steel

0 IntroductionThe flowleading pipe in pusher of shipping diesel en-gine is constructed by butt welding of 1Cr18Ni9Ti auste-nitic stainless steel circumferential strip with low carbonsteel circumferential strip. It is easy to form stress cracks,slag inclusions, and blowholes etc inside the weldedseam. Thus after turning for the weldment it is necessaryto perform nondestructive test for the welded joint.The weldment is very large in dimension and it is adouble deck construction with vertical a…     

Facile chromaticity approach for the inspection of passive films on austenitic stainless steel

A chromaticity approach for the inspection of passive films on 304 stainless steel is explored by measuring the redness degree of the colouration reaction product of phenanthroline. The measurement exhibits good capability in evaluating film quality. The measured values are dependent on the structural integrity of the passive films. Based on the electrochemical examination and XPS spectra, this approach is discussed from the view point of the inhibition of the passive films on the release of ferrous from the matrix during its reaction with phenanthroline. The preferential dissolution of Fe-rich oxides in the films can affect the measurement.     

奥氏体不锈钢焊接接头晶间腐蚀断裂分析

核电站管道大多采用奥氏体铁素体不锈钢制成,以主管道为例,多数采用焊接方式进行连接。在现场应用之前,需要进行工艺评定的焊接和检验,以验证焊接接头是否满足高温、高压、高腐蚀的性能要求。晶间腐蚀按照标准RCCM+RCCM2000补遗中MC1312.3中B法处理后,在弯曲过程出现裂纹,对比试样也出现裂纹,难以判定是否是晶间腐蚀造成的裂纹缺陷。利用金相方法观察出现裂纹的试样,结合力学性能试验和化学成分进行分析得出,弯曲受检面产生的裂纹不是由晶间腐蚀造成的。     

Modelling weld bead geometry using neural networks for GTAW of austenitic stainless steel

Abstract

The authors analyse the importance of different weld control parameters on the weld pool geometry of gas tungsten arc welding using an online feature selection technique that suggests weld voltage and vertex–angle pair as more important than the weld voltage and torch speed pair. Using the selected features multi layer perception and radial basis function networks are developed for prediction of bead width, penetration depth, and bead area. With cross-validation the authors have extensively studied the performance of composite models (one model for all outputs) and individual models (one model for each output). The individual models are found to work better than composite models. Usually, radial basis function networks are found to work better than the multi layer perception networks. To assess the influence of weld control parameters the authors have studied the performance of both networks using different combination of inputs. Overall, the performance of the proposed models is found to be quite satisfactory.     

Electrochemical aspects of stress corrosion crack growth in austenitic stainless steel

The stress corrosion crack velocity and stress corrosion threshold stress intensity, K_Isce, at potentials at or slightly different to the open circuit potential have been measured under potentiostatic control for 18Cr10Ni0.5Ti stainless steel in aqueous 46% LiCl at 105°C. In all cases, both stage 1 and stage 2 growth rate dependence on K is demonstrated. For potential vs. corrosion potential values 360 to ?50mV, a linear dependence of stress corrosion threshold stress intensity on the square root of the polarization applied was found.