Means of increasing the cold strength of cast steels

Leningrad Technological Institute for the Refrigeration Industry. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 2–6, May, 1990.     

Fatigue strength improvement of stainless steel using weld toes dressing with low transformation temperature welding wire

In the present study, low transformation temperature welding wire (LTTW), which can induce residual compressive stress around 304L welded joints, has been developed to improve the fatigue performance of welded joints. Procedure of design and chemical composition of weld metal and deposited metal of LTTW are introduced. The microstructure of weld metal of LTTW is composed of low carbon martensite and residual austenite. The residual stress distribution of a single welding bead of LTTW was measured and the result shows that compressive residual stress is generated. In addition, fatigue test was also carried out on no-load cruciform welded joints of 304L stainless steel under three conditions: as welded, 308L dressing and LTTW dressing. The result shows that the fatigue life of LTTW dressing joints (2×10⁶ cycles) is improved by 14–23 times and 3–6 times compared with that of as welded joints and 308L dressing joints.     

双相不锈钢药芯焊丝GDQA2205的研制

对所研制焊丝进行气体保护焊试验,测试了焊缝金属的化学成分、金相组织、抗拉强度、点蚀率和接头的洛氏硬度、抗弯强度和冲击韧度.用金相显微镜对焊缝金相组织进行观察,用扫描电镜分析冲击断口的形貌,并且用EDS能谱仪分析夹杂物的成分.结果表明,在焊丝中加入合理的Ni和MnN,可有效地促进奥氏体的形成,使焊缝获得合理的奥氏体铁素体两相组织.还分析了耐点蚀性能和冲击韧度的影响,研究发现除化学成分外,均匀的两相组织有利于改善耐腐蚀性能;金属元素Mn,Ni,Cr等是焊接接头冲击韧度的保证.     

拉丝过程中温升对高碳钢丝扭转性能的影响

设计了一系列的模拟试验,研究了拉丝过程中温升对高碳钢丝扭转性能的影响,确定了钢丝扭转性能恶化的临界回火温度为140℃。三维原子探针分析结果表明:渗碳体中的碳原子在回火过程中发生溶解且在铁素体中局部偏聚,聚集的碳原子对位错运动起到了钉扎作用,降低了铁素体的塑性,这是钢丝扭转性能下降的根本原因。     

双相不锈钢焊接接头疲劳强度

试验对SAF2205双相不锈钢纵向角接板焊接接头的疲劳强度进行了研究，用有限元计算热点应力集中系数，分别得出了名义应力和热点应力疲劳S-N曲线；用国际焊接学会推荐的方法进行统计处理，并和相同接头形式结构钢的疲劳强度进行了比较。试验表明，双相不锈钢纵向角接板焊接接头名义应力疲劳强度试验结果为FAT136，热点应力疲劳强度试验结果为FAT163，高于相同接头形式结构钢的疲劳级别；双相不锈钢的静载强度级别对其疲劳强度设计级别没有明显的影响。     

Resistance microwelding of 316L stainless steel wire to block

Abstract

The excellent corrosion resistance of low carbon vacuum melted 316 stainless steel coupled with its non-magnetic properties makes it ideal for biomedical applications. The typical joint geometry for microcomponents, such as medical implants, includes joining of fine wire to a larger block. However, this type of joint has received little attention in the current literature. The present study was conducted to examine the microstructure and mechanical properties of low carbon vacuum melted 316 stainless steel wire welded to a larger block. Results revealed solid state bonding occurring at low currents, while fusion bonding occurred at higher currents. This was due to the highly asymmetrical heat generation resulting in almost complete melting of the wire before the initiation of interfacial melting. This is a distinctly different bonding mechanism compared to previous studies on crossed wire joints.     

不锈钢自保护药芯焊丝脱渣性研究

为了定量分析药芯焊丝渣系组分对不锈钢自保护药芯焊丝脱渣性的影响,采用极端顶点混料回归设计方法,利用stat-ease公司出品的Design Expert 8.0软件进行试验设计与结果分析,试验中,将渣系中七种组分作为自变量,焊缝的脱渣率作为目标函数,建立了脱渣率与渣系组分的数学模型;并且根据二维等值图与三维响应曲面图直观的观察当固定4种组分的含量时,其它3种组分对因变量的影响情况;利用软件的优化求解功能,得出脱渣率最高的渣系组分理论配比,经实际验证,方程拟合良好,实际脱渣率与预测脱渣率相近,说明该方法对药芯焊丝渣系设计具有指导意义。     

药皮焊丝在不锈钢管道焊接中的应用

通过如何解决低温工况下不锈钢钢管焊接易出现的敏化腐蚀，热裂纹，焊口背面焊缝氧化等问题及焊接接头低温冲击韧度影响问题，详细阐述了不锈钢药皮自保护氩弧焊焊丝在工程中的应用。     

不锈钢药芯焊丝在复合板焊接中的应用

介绍了采用不锈钢药芯焊丝CO2气保焊焊接20R／SUS321复合钢板压力容器的工艺试验,并对焊缝进行了化学成分、硬度、力学性能、耐晶问腐蚀试验,证明了不锈钢药芯焊丝焊接复合板不仅能保证焊缝质量而且大大降低了焊接成本,并对产品焊接要点进行了简要说明。     

Galvanic current induced by heterogeneous structures on stainless steel wire

Galvanic corrosion could be initialized between the heterogeneous structures of an implant and the resulting corrosion products could act as a trigger for thrombosis and inflammation leading to restenosis after deployment of implant inside the artery. Experimental evidence showed that there were significant differences in the electrochemical behaviors among the different grain sizes of an implant. Galvanic current was detected between different grain sizes of 316L stainless steel wires both in vitro and in vivo. Severe corrosion and thrombosis were observed at anodic sites. Results demonstrated that homogeneous structure is the essential requirement for an implant in order to minimize the development of galvanic corrosion and to prevent its aftermath after percutaneous transluminal coronary angioplasty (PTCA).     

TIG welding-brazing joint of aluminum to stainless steel with hot wire

TIG welding-brazing process with high frequency induction hot wire technology was presented to create joints between 5A06 aluminum alloy and SUS32! stainless steel using ER1100 filler wire with different temperature. The joints were evaluated by mechanical test and microstructural analyses. The welding procedure using hot fiUer wire （400 ℃ ） significantly increases strength stability by 71% and average value of tensile strength by 30. 8 % of the joints, compared with cold wire. The research of microstructures in interfaces and welded seams reveals that using 400 ℃ hot filler wire can decrease the thickness of intermetallic compounds （ IMCs ） from 6 to 3.5 txm approximately, which is the main reason of mechanical property improvement.     

不锈钢药芯焊丝立焊性的分析与评价

利用汉诺威分析仪对4种不同配方的不锈钢药芯焊丝的立焊性能进行了电弧参数测试,分析焊接电流、电弧电压、短路时间的概率密度分布及它们的均方差与电弧稳定性和熔滴过渡的关系.结果表明,焊接电流、电弧电压及短路时间t1的均方差越小,有效短路过渡次数的比率越大,则焊丝熔滴短路过渡的均匀性和稳定性越好,飞溅也越小,立焊效果越好,对药...     

时效温度对超高强度不锈钢缺口抗拉强度的影响

借助轴对称光滑和缺口拉伸试验,研究了时效温度对超高强度马氏体时效不锈钢固溶和冷拔状态弹簧钢丝缺口抗拉强度的影响。研究结果表明：时效前的冷加工具有增强时效动力学的作用,降低了光滑和缺口拉伸抗拉强度峰时效温度,而且冷加工具有明显的强化效应,但强化效果随时效温度的提高逐渐衰减。从提高材料和构件的可靠性考虑,推荐500 ℃和480 ℃分别为固溶态和冷拔态钢丝的时效温度。     

烧结不锈钢丝网多孔板材的冲压成形研究

以烧结不锈钢丝网多孔板为材料,在室温条件下通过胀形试验和筒形拉深试验研究材料的冲压成形性能。胀形试验结果显示,材料的胀形极限随着厚度及直径的增大而增大;厚度为1. 4和1. 75 mm的多孔板在直径Φ110 mm的冲模下胀形高度达到30 mm未出现破裂,说明材料具有良好的塑性。筒形拉深试验显示,拉深力随板材的厚度、直径的增大而增大,随孔隙率的增大而减小;厚度为1. 2 mm时,拉深极限比为1. 8。根据塑性力学基本理论,推导了烧结不锈钢丝网多孔板的拉深力预测公式,将理论预测与实际试验数据对比,验证了公式的适用性。研究结果表明,烧结不锈钢丝网多孔材料具有较好的塑性,可进行冷冲压成形,有助于拓展多孔隙功能材料的应用领域。