Surface analysis of a cold leg section of an SS316-lithium loop

Compatibility studies of austenitic stainless steel AISI 316 with liquid lithium for fusion application have shown that a porous ferritic layer is formed on the surface of the steel in the hot leg of a loop experiment due to depletion of alloying elements. The concentration profiles of the removed elements across the cross section of the tube reveal a pronounced step between the austenite matrix and the porous ferrite which is not expected in a normal diffusion process. The removed elements are partly deposited on the surface of the cold leg.In this study we looked at the boundary between the nickel rich deposit and the original matrix of a section of the cold (435 °C) leg. On the surface of the austenite, the expected grain boundary attack of lithium was observed. Additionally, to a depth of about one grain size, chromium and molybdenum were depleted and lithium seemed to also have attacked the bulk material, resulting in a splitting up into smaller grains with decomposed concentrations of the alloying elements, i.e. iron with large amounts of nickel and iron with chromium and small nickel amounts.In this paper a suggestion is put forward describing a reaction mechanism leading to the porous layer in the hot leg as a result of the instability of AISI 316 and its decomposition into two phases under the influence of liquid lithium.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

药皮组分对不锈钢焊条工艺性能的影响规律

焊条药皮成分对不锈钢焊条工艺性能有较大的影响。通过对近百种焊条的药皮组分进行调配 ,发现碳酸盐与氟化物的比值对稳弧性、焊接飞溅以及焊缝成型等性能的影响很大。TiO2 与硅铝酸盐之比应不小于 3.5∶1,以防止出现粘渣。加入硅、钛等强脱氧剂会显著改善焊条的脱渣性能。药皮厚度对焊条工艺性能也有较大的影响。药皮厚度越大 ,焊接飞溅率越低 ,脱渣性能越好。     

用 N_2 背面保护焊接奥氏体钢管

研究了采用ＴＩＧ焊技术焊接１Ｃｒ１８Ｎｉ９Ｔｉ钢管子时，以Ｎ２代替Ａｒ背面保护焊缝的组织和性能，分析了根部焊缝表层中的Ｎ和Ｏ元素的分布，测量了焊缝中的δ－铁素体、Ｎ和Ｏ的含量．研究结果表明：Ｎ２可以代替Ａｒ背面保护１Ｃｒ１８Ｎｉ９Ｔｉ钢焊缝，焊缝表层的Ｎ，Ｏ的分布和焊缝中的δ－铁素体、Ｎ和Ｏ的含量无明显变化，焊接接头性能良好．     

NaCl溶液中20Cr9Ni5Co14不锈钢电化学腐蚀行为

采用电化学极化技术(动电位极化技术、线性极化技术和循环极化技术)和交流阻抗技术研究了不同条件下20Cr9Ni5Co14超高强度不锈钢的电化学腐蚀行为,并采用扫描电镜对极化后腐蚀形貌进行了表征.结果表明,20Cr9Ni5Co14钢在3.5%(质量分数)Na Cl溶液中出现钝化.随着Na Cl浓度的升高,钝化现象消失,而自腐蚀电流密度从8.223×10-7A/cm2减小至1.129×10-7A/cm2;随着p H值的降低,20Cr9Ni5Co14钢的致钝电位和过钝化电位增加.在p H值高于3时,腐蚀产物膜具有良好的耐腐蚀性能而导致反应步骤成为控制步骤.而当p H值降低到2时,腐蚀产物溶解速度很快,金属界面发生腐蚀速率很大,浓差极化成为了控制步骤.对腐蚀形貌研究表明,20Cr9Ni5Co14钢在极化过程中出现点腐蚀,导致了材料的耐腐蚀性能下降.     

不锈钢水下激光焊接焊缝成形与力学性能

摘要： 采用水下局部干法激光焊接技术对1 mm厚SUS304不锈钢进行了焊接试验,重点分析了水深及保护气体流量对焊缝成形与力学性能的影响.实验结果表明：通过适当的水深与保护气体流量匹配,可以获得成形良好、剪切拉伸强度与母材相当的焊缝.在水深一定时,随着气体流量的增加,焊缝熔宽变宽,熔深变浅,深宽比减小.在气体流量一定时,随着水深的增加,焊缝熔深和熔宽也表现出类似的变化规律.与普通激光焊接相比,水下激光焊接改变了焊缝的散热方向以及散热速度,因此同一焊接工艺参数下,水下激光焊接的熔深变浅,熔宽变宽.
关键词： 水下焊接; 激光焊; 奥氏体不锈钢; 焊缝成形; 力学性能
中图分类号： TG 456.7文献标志码： A     

Effect of surface nanocrystallization induced by fast multiple rotation rolling on hardness and corrosion behavior of 316L stainless steel

A nanostructured layer was fabricated by using fast multiple rotation rolling (FMRR) on the surface of 316L stainless steel. The microstructure in the surface was characterized by transmission electron microscopy and X-ray diffraction. The effects of FMRR on the microhardness, surface roughness and corrosion behavior of the stainless steel were investigated by microhardness measurements, surface roughness measurements, potentiodynamic polarization curves and pitting corrosion tests. The surface morphologies of pitting corrosion specimens were characterized by scanning electron microscopy. The results show that FMRR can cause surface nanocrystallization with the grain size ranges from 6 to 24 nm in the top surface layer of the sample. The microhardness of FMRR specimen in the top surface layer remarkably increases from 190 to 530 HV. However, the surface roughness slightly rises after FMRR treatment. The potentiodynamic polarization curves and pitting corrosion tests indicated that the FMRR treated 316L stainless steel with a surface nanocrystallized layer reduced the corrosion resistance in a 3.5% NaCl solution and enhanced the pitting corrosion rate in a FeCl₃ solution. Possible reasons leading to the decrease in corrosion resistance were discussed.     

恒电位脉冲法检测高纯铁素体不锈钢的敏化

用恒电位脉冲（ＰＰＴ）法对高纯铁素体不锈钢的敏化度进行了检测，并与传统的动电位再活化（ＥＰＲ）法进行了比较，结果表明：ＰＰＴ法可以用来检测铁素体不锈钢的敏化，并且具有检测速度快，表面损伤小的优点     

合金元素及模拟热处理对2205双相不锈钢之孔蚀性质影响

本文研究了Ｎｉ元素及不同模拟焊后热影响区（ＨＡＺ）组织对２２０５双相不锈钢孔蚀性质之影响。结果发现：在研究成分范围内，不同Ｎｉ含量对于底材电化学极化曲线之影响不大，其Ｅｎｐ和Ｅｎｐ均在１１００￣１２００ｍＶ之间。     

改变Cr、Ni配比电弧炉冶炼超低碳不锈钢HoCr19Ni12Mo2

冶炼超低碳不锈钢因含碳极低（Ｃ≤０．０３０％）而使冶炼难度相当大，本文以ＨｏｏＣｒ１９Ｎｉ１２Ｍｏ２为例论述了通过调氧化前Ｃｒ、Ｎｉ的配比来降低氧化终点温度，从而降低冶炼难度     

Ce-Pt-Pd/不锈钢丝网催化剂的制备与催化性能

采用阳极氧化技术在不锈钢丝网上自生长了一层结构致密的阳极氧化膜,并以此为载体,制备出一种高活性、高稳定性的负载型Ce-Pt-Pd催化剂.考察了该系列催化剂对甲苯、丙酮和乙酸乙酯的氧化活性,并用扫描电镜、X射线光电子能谱和程序升温氧化技术对催化剂进行了表征.结果表明,不锈钢丝网载体表面自生长的氧化物膜十分有利于活性组分的负载,制得的催化剂具有较高的催化燃烧有机化合物的活性和稳定性.