载气热提取法测定熔敷金属中扩散氢收集条件的探究

探究了GB/T 3965—2012《熔敷金属中扩散氢测定方法》中载气热提取法收集条件对测定扩散氢含量的影响,并与水银法进行了对比。研究结果表明,样本炉温设定为400℃,A型试块的内部温度大约在51 min时稳定在358℃左右,B型试块内部温度大约在27 min时稳定在391℃左右;载气热提取法电信号曲线收集结束点的电信号及斜率均接近0时获得的结果与水银法具有较好的一致性。     

药芯焊丝熔敷金属中扩散氢含量不同测定方法的对比研究

熔敷金属中的扩散氢含量,是产生延迟裂纹的主要原因之一.为防止产生裂纹,除焊前、焊后采取适当的热处理、合适的焊接工艺之外,选用高质量、低氢含量的焊接材料也是极为关键的元素.文中就测试E501T—1型药芯焊丝熔敷金属中的扩散氢含量使用不同标准、不同方法进行对比,客观地总结了它们之间的区别,以方便用户选择合适的标准和试验方法对焊接材料进行扩散氢检验.     

熔敷金属扩散氢逸出的数学模型

针对酒精法测氢中扩散氢从试样表面逸出的试验现象,根据菲克第一、第二定律,引入了表面氢传输系数h,在此基础上,建立了氢非稳态扩散时,利用试样的初始含氢量、扩散系数、表面氢传输系数及试样半径计算扩散氢逸出量-逸出时间关系曲线的数学模型。对实测的扩散氢逸出曲线的拟合结果表明,焊缝金属的表面状况对其中所含扩散氢的逸出行为有较大影响,是研究焊接接头氢扩散行为时必须考虑的因素。利用该数学模型成功解释了酒精法测氢中的一些试验现象,表明该模型具有良好的实用价值。     

熔渣的溶氢能力与熔敷金属的扩散氢

分别改变碱性焊条熔渣中CaO和Mgo与气保护药芯焊丝熔渣中Al2O3和MgO组元的相对含量,研究其对熔敷金属扩散氢的影响.结果表明,碱性焊条熔渣中,用同等质量MgO取代CaO导致熔敷金属扩散氢大幅度提高;药芯焊丝焊接熔渣中,脱氧产物若不是以Al2O3为主而是以MgO为主,熔敷金属扩散氢则大幅度提高.分析认为,熔渣成分的变化导致其溶氢能力的变化是这一结果的主要因素,即Ca2 离子导致熔渣含氧量的提高及氢在Al2O3中具有较高的溶解度等提高了熔渣的溶氢能力.     

钛对药芯焊丝熔敷金属扩散氢的影响

通过添加不同量的钛铁到药芯焊丝中,并在不同保护气焊接的条件下,研究其对熔敷金属扩散氢的逸出和含量的影响.结果表明,保护气体氧化性的增加可以降低熔敷金属扩散氢,而保护气还原性的增加,则熔敷金属扩散氢含量也会相应增加;在药芯焊丝中加入一定量的钛铁,一方面TiO,Ti(C,N)颗粒会在熔敷金属中形成的不可逆氢陷阱,对氢产生捕获作用,可以降低熔敷金属扩散氢;同时,加入的钛铁会提高电弧气氛的还原性,这样会增加熔敷金属的扩散氢,所以适量的添加钛铁,使钛铁对焊接气氛的氧化性的影响和形成不可逆氢陷阱的作用之间合理的结合,能达到理想的降氢效果.

Abstract：

The effects of Ti content on diffusible hydrogen escape characteristic of deposited metal of flux cored wire were investigated by adding different quantities of Ti-Fe and in different protecting gas conditions. The results show that the oxidative susceptibility of protecting gas can decrease the diffusible hydrogen of deposited metal, and the grains of Ti and Ti(C,N) which exhibit irreversible hydrogen traps can also decrease the diffusible hydrogen of deposited metal. The rational adding Ti-Fe, which harmonized the oxidative susceptibility of welding atmosphere and formed the irreversible hydrogen traps, could obviously decrease the diffusible hydrogen of deposited metal.     

焊条原始状态对焊缝金属中扩散氢含量的影响

选用E5015、E8515和E9018三种焊条,分别在常温、200℃×1 h,400℃×1 h三种烘焙温度下分析研究焊缝金属中扩散氢含量。结果表明:随着焊条烘焙温度的升高以及熔敷金属抗拉强度的增大,焊缝金属中扩散氢的含量逐渐减少;常温状态下的焊条其焊缝中马氏体和上贝氏体比烘焙条件下的多;E5015焊条和E8515焊条,其焊缝中板条状铁素体多于E9018焊条,而粒状贝氏体少于E9018焊条。     

空气湿度和钢板初始温度对高强钢熔敷金属扩散氢含量的影响

通过一系列高强钢熔敷金属扩散氢含量的试验,系统地研究了空气湿度和钢板初始温度对焊缝扩散氢含量的影响.结果表明,空气湿度和钢板初始温度对高强钢焊接接头中扩散氢含量有十分明显的影响,通过降低空气湿度和提高钢板的初始温度,是降低高强钢的焊接接头扩散氢含量的有效措施.     

E5015药皮原料粒径对其熔敷金属扩散氢含量的影响

为了研究药皮原料粒径对E5015焊条熔敷金属扩散氢含量的影响,特选取氟石和大理石作为研究对象。对氟石和大理石粉料进行时间梯度球磨、购买纳米大理石粉料、用SEM对粒径观察、对氟石系列和大理石系列进行焊条制备和测试。试验结果表明:氟石原料经过时间梯度球磨后粒径明显减小,焊后熔敷金属扩散氢含量明显降低。随着大理石粒径的减小,焊条熔敷金属扩散氢含量逐渐下降,但随着纳米大理石相对含量的增加,扩散氢含量有逐步升高的趋势。总之,原料粒径的细化对焊条熔敷金属扩散氢含量的减小有明显作用。     

Investigation of the effective coefficient of hydrogen diffusion in the conditions of the thermal cycle of welding

Experimental equipment and the method of measuring the effective coefficient of hydrogen diffusion in the conditions of the thermal cycle of welding are described. The temperature dependences of the coefficient for ferritic–pearlitic, martensitic, bainitic, maraging and austenitic steels, reflecting the special features of the chemical composition and structural transformations in the welding conditions, are determined.     

Control of the diffusible hydrogen content in different steel phases through the targeted use of different welding consumables in underwater wet welding

Due to the rising number of offshore structures all over the world, underwater wet welding has become increasingly relevant, mainly as a repair method. Welding in direct contact with water involves numerous challenges. A topic focused by many studies is the risk of hydrogen-induced cracking in wet weldments due to hardness values of up to 500 HV 0.2 in the heat-affected zone (HAZ) and high levels of diffusible hydrogen in the weld metal. The risk of cracking increases as the equivalent carbon content rises, because the potential to form martensitic structures within the HAZ rises too. Thus, high-strength steels are especially prone to hydrogen-induced cracking and are considered unsafe for underwater wet repair weldments.     

纯镁渗锌处理表面合金化机制研究

对纯镁进行了表面渗锌处理，研究了扩渗温度及扩渗时间对于合金化渗层组织、相结构及反应层连续性的影响。结果表明：扩渗温度的选择有一个合适的范围，温度过低，扩渗速度太慢甚至Zn元素原子的能量达不到其激活能，不能产生活性原子，扩渗过程无法进行。温度过高虽然有利于形成合金化渗层，但会使基体晶粒粗化，甚至改变整个基体，而且，温度过高不利于反应层（金属间化合物区）的稳定：扩渗时间的延长会促使Zn的进入量和金属间化合物的生成量增加，并削弱晶界扩散优势的影响，最终使固溶层和反应层趋于均匀化。要形成连续的反应层，扩渗温度应控制在400℃～420℃，相应的扩渗时间为8h以上。     

Effect of deformation temperature on the hot compressive behavior of metal matrix composites with misaligned whiskers

A multi-inclusion cell model is used to investigate the effect of deformation temperature and whisker rotation on the hot compressive behavior of metal matrix composites with misaligned whiskers. Numerical results show that deformation temperature influences the work-hardening behavior of the matrix and the rotation behavior of the whiskers. With increasing temperature, the work hardening rate of the matrix decreases, but the whisker rotation angle increases. Both whisker rotation and the increase of deformation temperature can induce reductions in the load supported by whisker and the load transferred from matrix to whisker. Additionally, it is found that during large strain deformation at higher temperatures, the enhancing of deformation temperature can reduce the effect of whisker rotation. Meanwhile, the stress-strain behavior of the composite is rather sensitive to deformation temperature. At a relatively lower temperature （150℃）, the composite exhibits work hardening due to the matrix work hardening, but at relatively higher temperatures （300℃ and above）, the composite shows strain softening due to whisker rotation. It is also found that during hot compression at higher temperatures, the softening rate of the composite decreases with increasing temperature. The predicted stress-strain behavior of the composite is approximately in agreement with the experimental results.