双相不锈钢气保护焊工艺研究

双相不锈钢以其优良的耐腐蚀性能和抗拉强度,在船舶制造、海洋平台、造纸设备、石化设备和桥梁建造等行业得到越来越多的应用.介绍了双向不锈钢气保焊的操作工艺和焊接参数的选择,为这些行业的双相不锈钢焊接提供一些参考.     

双相不锈钢小径管焊缝相控阵检测工艺及应用

在海洋工程平台的建造中,相控阵检测技术已经成功地应用于工艺管线焊缝的检验中,提高了工艺管线的检验效率,降低了项目成本。对于双相不锈钢工艺管线焊缝基本只用于?254 mm及以上规格的焊口,对于小管径的双相不锈钢焊缝,相控阵检验技术很少应用。文中介绍了?101.6 mm双相不锈钢小径管相控阵检测技术的试块加工设计、检测工艺和现场应用。     

UNS S32750超级双相不锈钢的CMT+P焊接工艺

综合考虑UNS S32750超级双相不锈钢冷金属过渡与脉冲(CMT+P)单道焊缝的宏观形貌、成形系数及铁素体/奥氏体两相比例等因素,探究了保护气类型、焊接速度、送丝速度及CMT/P比值等工艺参数对焊缝成形质量的影响规律。结果表明：UNS S32750超级双相不锈钢最优的CMT+P单道焊接工艺参数为：Ar保护气(流量15 L/min)、焊接速度为3～5 mm/s、送丝速度为8 m/min、CMT/P比值为1/32～1/64。以优化的单道焊接工艺参数范围为指导,成功制备了成形质量良好的UNS S32750双相不锈钢CMT+P对焊接头。     

Z6CNDU20-08M循环泵叶轮铸造缺陷补焊工艺

为了确定超级双相不锈钢Z6CNDU20-08M循环泵叶轮铸件缺陷补焊修复工艺,按照《压水堆核岛机械设备设计及建造》RCC-M S标准,对该静态铸造双相不锈钢叶轮从材料焊接性、力学性能、耐点蚀及缝隙腐蚀、耐晶间腐蚀等性能进行试验分析。通过选用合理的焊接工艺参数、匹配的焊接材料,确保补焊后的铁素体(α)-奥氏体(γ)双相钢组织相平衡,满足叶轮使用过程耐腐蚀性能及各项力学性能要求。结果表明,合理的焊接工艺确保化学成分、力学性能及耐腐蚀性能均满足标准和客户技术规范,为叶轮铸造缺陷修复补焊提供合理工艺方案。     

2205双相不锈钢在盐卤介质中腐蚀行为的研究

实验采用电化学方法探究CO32-浓度、S2-浓度、pH值以及流速等工艺参数的改变对2205双相不锈钢(2205DSS)在盐卤介质中腐蚀行为的影响.结果表明,采用两碱法的最佳制盐工艺参数值为:S2-浓度1.00 g/L;pH=8.35;流速1.80 m/s;CO32-浓度1.00 g/L.在此工艺参数下可缓解设备腐蚀.     

铸造工艺对双相不锈钢泵体裂纹的影响

本文针对双相不锈钢泵体制造过程的关键点和难点,在铸造工艺、冶炼工艺、热处理工艺方面采取了多项技术措施,成功解决了双相不锈钢泵体的裂纹问题.     

超级双相不锈钢UNS S32750的焊接

本文介绍了UNS S32750超级双相不锈钢的焊接，通过对其焊接性能的分析，提出焊接工艺评定方案并获得合适的焊接工艺参数，应用于实际工程中，取得了满意的效果。     

SAFUREX双相不锈钢与A106B异种钢的焊接

SAFUREX双相不锈钢是瑞典Sandvik公司与荷兰Stamicarbon公司合作开发的新一代尿素专用高级双相钢。针对SAFUREX双相不锈钢与A106B的理化性能,分析该异种钢的焊接性。通过在重庆建峰化工第2套化肥工程中具体应用表明,选取合适的焊接材料和焊接工艺参数,能够获得性能优良的焊接接头。     

2205双相不锈钢与304奥氏体不锈钢的焊接

采用焊条电弧焊(SMAW),以E2209作填充材料对2205双相不锈钢与304奥氏体不锈钢异种金属焊接工艺进行研究,通过优化焊接工艺参数,获得了具有良好力学性能和合适双相比例的焊接接头.接头力学性能测试表明,拉伸试样断裂发生在强度相对较低的304母材侧;2205母材侧热影响区的显微硬度值高于焊缝和2205母材,而304...     

石化装置用SAF2205钢的焊接

SAF2205双相不锈钢焊接接头的力学性能和耐蚀性取决于接头能否保持适当的相比例.正确选用焊接材料、严格控制焊接热输入量以及制定合理的焊接工艺是双相不锈钢焊接的关键.进行了双相不锈钢的焊条电孤焊、手工钨极氩弧焊对接焊缝焊接工艺评定及产品的施焊,各项技术指标均满足要求,证明所选用的焊接方法、焊接材料、焊接工艺正确合理.     

高速船用高强度双相不锈钢

以前，Cr13和Cr18Ni8系列不锈钢被用于制造船体零件，前者在海水中的耐蚀性不良，后者强度性能不够高，于是发展了既具有高强度又耐海水腐蚀的铁素体-奥氏体系列双相不锈钢，用于制造高速船的船体钢板、锻件（舵轴、舵柱、舵梢、尾轴、中间轴等）和铸件（螺旋桨、阀体、耐蚀叶轮等）。双相不锈钢已经得到国际上多个船级社的认可。     

Friction stir welding of duplex stainless steels

Duplex stainless steels are successful in a variety of applications such as the food industry, petrochemicals and plants for desalination of seawater, where high corrosion resistance and high mechanical strength are required. However, the beneficial microstructure may change during fusion welding steps, and it can compromise the performance of these materials. Friction stir welding is a solid-state process avoiding typical problems concerning solidification such as solidification cracks, liquation and segregation of alloying elements. Superduplex stainless steels can avoid unbalanced proportions of ferrite and austenite, formation of secondary deleterious phases and grain growth of ferrite in the heat-affected zone. Consolidated friction stir welded joints with full penetration 6 mm thick were obtained for UNS S32101 and S32205 duplex and S32750 and S32760 superduplex stainless steels. The friction stir welds were submitted to tensile tests indicating an improvement of strength in welded joints, showing increased yield and tensile strength for all studied cases. Regarding the microstructural characterization, an outstanding grain refinement was observed in the welded joint, achieving grain sizes as small as 1 μm. This refinement was associated with the combination of microstructural restoration mechanisms in the dual-phase microstructure promoted by severe deformation associated with a high temperature during the welding process.     

780 MPa级冷轧双相钢的组织与性能研究

在实验室试制了780MPa级冷轧双相钢,介绍了其成分设计、轧制工艺和连续退火工艺。研究了过时效温度对钢板力学性能和显微组织的影响,并利用扫描电镜和透射电镜对钢的显微组织进行了分析。结果表明,试制的冷轧双相钢经820℃保温,320℃过时效处理,可以获得综合力学性能优良的冷轧双相钢,其屈服强度为408MPa,抗拉强度为812MPa,伸长率达到了23.1%。     

Chloride-induced stress corrosion cracking of Duplex stainless steels. Models,test methods and experience

Stress corrosion cracking (SCC) induced by chlorides frequently causes problems in applications where standard austenitic stainless steels are being used. Often this problem can be solved by the use of duplex stainless steels. In this report the mechanisms for SCC have been surveyed, and the cause for the high SCC resistance of duplex stainless steels has been discussed and evaluation of test methods for SCC and how duplex stainless steels respond to them, as well as practical experience of duplex stainless steels. The study shows that no single mechanism can be attributed to the good resistance to SCC of duplex stainless steels. Probably a synergistic effect of electrochemical and/or mechanical effects is responsible for the good performance. Test methods for SCC often give relatively good correspondence with real applications, but ranking is often doubtful, and comparisons of different material types should be made with caution. Numerous cases with SCC on standard austenitic stainless steels have been solved by the use of duplex stainless steels.     

液固流动下攻角对不锈钢冲刷腐蚀的影响

采用自制的动态旋转冲刷腐蚀装置 ,以含硅湿法磷酸为液固冲刷腐蚀介质 ,考察了该流动体系中 316L和 90 4L不锈钢在不同攻角下冲刷腐蚀的行为。材料的电化学极化曲线表明 ,两种不锈钢在硅湿法磷酸中均出现钝化现象 ,且 90 4L为自钝化体系。电子扫描电镜证实 ,两种材料在低攻角下主要受切削作用的影响 ,大攻角时以正向应力为主。冲刷腐蚀下 316L不锈钢的失重量在攻角 30 o、6 0 o 有所增大 ,90 4L则在攻角 30 o 时失重量最大     

冷轧含Cr DP800双相钢的组织与性能

设计了两种不同成分的C-Mn和C-Mn-Cr冷轧双相钢。研究了在两相区温度热处理后其不同比例的F+M双相组织与力学性能的关系。结果表明,C-Mn-Cr钢在770℃保温5min后以10℃/min缓冷至690℃再水冷,可获得由平均晶粒尺寸为6.8μm的铁素体和体积分数约为31%的马氏体组成的双相组织,并具有抗拉强度为825MPa、屈服强度为451MPa和断后伸长率为15.4%的良好力学性能。     

耐候钢热处理双相化组织与性能

研究了铁路机车车辆用的两种热轧耐候钢经热处理双相化的的金相组织及各种力学性能,结果表明,耐候钢双相化后的显微组织由多边形等轴铁素体晶粒和不规则岛状马氏体组成,且原始组织对其有很大影响;两种热轧耐候钢双相化热处理前后的显微镜组织和力学性能均无明显的各向异性,研究发现,双相化加热温度对马氏体含量,铁素体晶粒大小,屈服现象,屈服强度、抗拉强度、屈强比、伸长率及加工硬化指数（n值）等双相化钢的组织和性能均有显著影响,根据试验结果,确定的耐候钢最佳热处理双相比工艺为780℃加热,10％NaCl水溶液淬火,本研究成果将为进一步采用控制轧制法进行耐候双相钢的生产奠定基础。     

热轧态Si—Mn系双相钢的组织转变

利用Ｇｌｅｅｂｌｅ－１５００热模拟试验机对试验钢进行了热模拟轧制。研究了在不同热轧工艺参数与合金化程度条件下Ｓｉ－Ｍｎ双相钢的组织转变。获得了估算热轧态Ｓｉ－Ｍｎ双相钢马氏体体积百分数和先共翁素体体积百分数的计算式。计算值与实测值相吻合，给出了ｆｍ－Ｔ－Ｖ和ｆＦｐ－Ｔ－Ｖ关系的三维图及相应的ｆＭ和ｆＦｐ等值线图。     

Novel strategies for assessing the pitting corrosion resistance of stainless steel surfaces

Pitting corrosion is one of the most common mechanisms of surface damage on stainless steels. Electrochemical methods have been preferentially applied for the evaluation of the pitting corrosion resistance of stainless steels in the laboratory. Nevertheless, some of them are not reliable enough and in general the application of electrochemical methods in the field becomes difficult because of required deep understanding of corrosive phenomena and measurement technology. Therefore, new approaches for the evaluation of the pitting corrosion susceptibility of stainless steel surfaces in the laboratory as well as in the field are necessary. In the present paper two novel strategies including electrochemical noise measurements under anodic polarization for laboratory testing, and an indicator test to assess the susceptibility of stainless steel surfaces to pitting corrosion in the field are introduced. Experimental results concerning the influence of surface treatments on the pitting corrosion resistance on stainless steels have confirmed that final surface condition has a significant effect on their future pitting corrosion susceptibility. In addition, the pitting corrosion resistance of stainless steel surfaces was observed being specifically dependent on the achieved surface topography and in some cases independent on the roughness parameters of the surface.     

Influence of chemical composition on the pitting corrosion resistance of non-standard low-Ni high-Mn-N duplex stainless steels

The pitting corrosion resistance of a new family of duplex stainless steels has been evaluated. These non-standard duplex stainless steels are characterised by low Ni content and high N and Mn levels. Potentiodynamic polarisation scans in NaCl solution have been carried out to determine pitting potentials. A crevice-free cell has been used to perform the electrochemical tests.An exponential equation is obtained in the regression analysis between the pitting potential and chemical composition which allows an estimate of the pitting resistance of these new duplex stainless steels.