焊接电流对Ti3Al/T C11合金焊缝区组织及合金元素扩散的影响

采用真空电子束焊对Ti₃Al合金与TC11合金进行焊接,研究焊接电流对Ti₃Al /TC11焊缝区组织及合金元素扩散的影响。结果表明,随焊接电流增大,焊缝区组织明显粗化,且晶粒尺寸差异逐渐减小;当焊接电流增大至25 mA时,焊缝区组织为粗大β柱状晶。焊接电流对焊缝区各合金元素含量影响较小,但对其均匀性影响较显著,这与焊缝区显微组织形貌有关。随焊接电流的增大,焊缝区合金元素含量均匀性变差。     

304不锈钢激光深熔焊元素蒸发及焊缝合金含量变化

通过模拟和试验的方法对激光深熔焊304不锈钢焊缝合金成分变化进行了研究. 利用电子探针X射线显微分析对母材及焊缝中的Fe,Cr,Mn,Ni元素含量进行分析. 基于对焊接熔池温度场和流场的计算,建立了深熔激光焊元素蒸发和焊缝合金含量变化的模型. 结果表明,深熔激光焊元素蒸发主要发生在小孔及熔池表面,其中小孔内金属蒸发强烈,而小孔外的熔池表面蒸发量较小. 与母材相比,焊缝中Mn,Cr元素含量减少,而Ni,Fe元素含量增加. 焊缝合金含量变化随焊接功率增大而减小,但对于焊接速度的改变不敏感. 计算结果与试验检测结果吻合良好.     

活性剂MATB-I铺设量对镁合金焊接的影响(Ⅱ)

从焊缝成形质量、熔深以及合金元素对焊缝作用角度,选择活性剂的组元,设计活性剂MATB-I配方,研究焊缝元素含量、焊缝的相组成物、焊缝抗腐蚀性,以及接头力学性能.研究表明:活性剂可使焊缝区的特征点元素含量变化,但整区元素含量变化不大;活性剂MATB-I可使焊缝区的Mg相增多,而Mg17Al12相减少,打断网状共晶体,明显细化合金组织,合金强度增加;与TIG焊缝相比,添加活性剂的焊缝耐蚀性得到提高,但两者均比母材弱;活性剂对抗拉强度影响较小,接头抗拉强度最小值为母材的89.04％,可以满足力学性能要求.     

合金元素钼含量对热铸模具钢组织和力学性能的影响

以热铸模具钢为研究对象,分析了合金元素钼的含量对模具钢组织和力学性能的影响。结果表明,当钼含量为3.2%时,热铸模具钢的磨损表面存在着剥落区和未剥落区两部分。在磨损表面的剥落区域存在着大量氧化物,热铸模具钢中的钼含量和回火温度对其磨损率有重要影响。当回火温度较低时,合金元素钼含量对热铸模具钢硬度的影响较为明显;当回火温度较高时,合金元素钼含量对热铸模具钢的硬度影响较小。     

活性剂MATB-Ⅰ铺设量对镁合金焊接的影响(Ⅱ)

从焊缝成形质量、熔深以及合金元素对焊缝作用角度,选择活性剂的组元,设计活性剂MATB-I配方,研究焊缝元素含量、焊缝的相组成物、焊缝抗腐蚀性,以及接头力学性能。研究表明:活性剂可使焊缝区的特征点元素含量变化,但整区元素含量变化不大;活性剂MATB-I可使焊缝区的Mg相增多,而Mg17Al12相减少,打断网状共晶体,明显细化合金组织,合金强度增加;与TIG焊缝相比,添加活性剂的焊缝耐蚀性得到提高,但两者均比母材弱;活性剂对抗拉强度影响较小,接头抗拉强度最小值为母材的89.04%,可以满足力学性能要求。     

嵌入纯钛薄板对TA15钛合金电子束焊焊缝成分及显微组织的影响

在TA15钛合金电子束焊对接接头中嵌入纯钛TA1金属薄片,通过改变焊缝的熔宽调控焊缝内的母材与嵌入材料的比例,以此实现对焊缝内合金成分含量的控制。通过对焊接接头及焊缝内元素分布特征的观察和分析,证明选用适当的焊接工艺参数可以实现合金元素的均匀分布,并可有效地细化焊缝组织、降低焊缝的显微硬度。     

钼铼合金的生产工艺及某些组织性能

前言对高铼含量的钼铼合金的研究,早在六、七十年代国外就有文献报导。而对低铼含量的钼铼合金研究极少。E.M.萨维茨基等指出,铼是能明显降低钼的冷脆转变点的唯一合金元素,钼中加入铼,可以提高     

添加Mo-Ti-Zr填充层的钼镧钇合金电子束焊接特性分析

为了研究TZM合金(Mo-0.5Ti-0.1Zr)填充层对钼镧钇合金电子束焊接性的影响,分析了焊接接头显微组织和力学性能。结果表明,钼镧钇合金直接电子束焊接接头焊后产生贯穿裂纹,而填加TZM合金后,实现了钼镧钇合金的有效焊接。Zr元素的加入降低了Mo的氧化物在晶界处的聚集程度,提高了晶界结合强度;接头各区域显微硬度不同,焊缝区显微硬度与母材相当,为270～290 HV,两侧热影响区显微硬度最低。添加TZM合金后,钼镧钇合金电子束焊接接头抗拉强度明显提高,拉伸断裂发生于焊缝区,为脆性沿晶断裂模式。     

钛钼合金膜制备及其吸氘性能

为提高中子管或中子发生器氚靶钛钼合金膜的吸氘性能,创新的采用钛靶和钼靶双靶磁控溅射方式在钼基片上循环沉积钛膜和钼膜,利用钛钼之间的注入与热扩散得到多层钛钼合金膜,利用辉光放电光谱仪(GDOES)研究了热扩散对多层(5层及10层)钛钼合金膜元素分布的影响。结果表明,500℃加热对合金膜中钛钼元素的均匀化扩散作用不明显,通过增大循环次数,减少每次循环各靶溅射时间,可有效提高合金膜的钛钼扩散程度。镀膜沉积循环次数由5次增加至10次,单次钛靶溅射时间由60 min降低至30 min,钼靶溅射时间由5 min降低至2 min,得到的合金膜钼元素含量峰值从39.5 at%降至8.24 at%,450℃下吸氘平衡时间从15 min降至6 min,平均氘钛比从1.05升至1.85。改进工艺后的钛钼合金膜,有效提高了合金膜的钛钼扩散程度及其吸氘性。     

提高17—4PH合金550℃时效强度的研究

研究了氮、钼、铜等元素含量、锻造变形、成品退火、热处理及冷处理制度对合金室温瞬时性能的影响。通过控制合金主要强化元素及微量元素含量,采用较低锻造加热温度及较大末火变形量的方法,使合金在550℃时效状态下组织性能达到美国宇航标准 AMS5643L 及国外实物水平。     

Microstructure and Mechanical Properties of 9Cr-1Mo Steel Weld Fusion Zones as a Function of Weld Metal Composition

Modified 9Cr-1Mo steel, designated as P91, is widely used in the construction of power plants and other sectors involving temperatures higher than 500 °C. Although the creep strength is the prime consideration for elevated temperature applications, notch toughness is also important, especially for welded components, as it is essential to meet the pressure test and other requirements at room temperature. P91 steel weld fusion zone toughness depends on factors such as welding process, chemical composition, and flux composition. Niobium and vanadium are the main alloying elements that significantly influence the toughness as well as creep strength. In the current work, weld metals were produced with varying amounts of niobium and vanadium by dissimilar joints involving P9 and P91 base metals as well as filler materials. Microstructural studies and Charpy V-notch impact testing were carried out on welds to understand the factors influencing toughness. Based on the results, it can be concluded that by reducing vanadium and niobium weld metal toughness can be improved.     

光束摆动和氮气合金化对钼合金接头组织和性能的影响

钼合金熔化焊接存在晶粒粗大、晶间偏析问题,导致接头力学性能差,采用激光束摆动和氮气合金化方法开展试验研究.结果表明,单独采用光束摆动措施后,焊缝区平均晶粒尺寸减小约28％,焊缝中心显微硬度从190?HV提高到200?HV,钼合金对接接头抗拉强度从29.83?MPa提高到130.03?MPa.单独采用氮气合金化(保护气体...     

TIG焊对低合金钢焊缝金属元素分布状态的影响

采用TIG焊,选取两种成分相近的焊丝,制备了两组低合金钢焊接接头.通过焊材的EDS成分分析、焊缝金属XRF元素分析以及元素分布状态图等手段,研究了焊材及母材的合金元素在焊缝金属中的存在状态和分布特征.结果表明,锰在ER307Si焊缝中较高,镍、铬在ER308LSi焊缝中较高,硅在两组焊缝金属中相差不大;铬、镍、锰、硅在ER307Si焊缝中的起弧处含量较高,在ER308LSi焊缝中的中间处含量较高;起弧处元素分布较均匀,熔合线附近分布较稀疏;焊缝中间位置Ni元素分布较疏,含量较低;收弧处各元素分布不均.     

电子束焊接热效应对镁合金焊缝显微硬度的影响

研究了真空电子束焊接热效应对AZ91D和AZ31B镁合金焊缝显微硬度的影响机制,实验结果表明,真空电子束焊接热效应对AZ91D、AZ31B镁合金焊缝均有不同程度的强化作用。当焊接热输入较大时,影响AZ91D镁合金焊缝硬度的主要因素为因Mg元素烧损而产生的强化相变化,焊接热输入越大,焊缝中的Mg元素烧损增加,使Al元素含量(质量分数,下同)逐渐增加,从而在焊缝中生成了更多的强化β相,使焊缝硬度得到提高,产生的强化相越多,焊缝硬度相对越大;当焊接热输入较小时,影响AZ31B镁合金焊缝硬度的主要因素为焊后冷却速度,焊接热输入越小,焊后冷却速度越快,焊缝晶粒越细小,焊缝硬度相对越大。     

Multipass pulsed current gas metal arc welding of P91 steel

Conventional gas metal arc welding of modified 9Cr–1Mo steels referred to as P91 steels is considered difficult due to loss of alloying elements and degradation of weld joint properties. In comparison to the conventional process, pulsed current gas metal arc welding allows more accurate control of heat input per unit length and electrode deposition and, thus, can be more suitable for the joining of P91 steel. A detailed experimental study is therefore undertaken to examine the roles of welding current, speed and groove angle in the weld bead profiles and joint properties in multipass pulsed current gas metal arc welding of 12?mm thick P91 steel. The results show that the joint properties are strongly influenced by the heat input per unit length and the groove angle. A groove angle of 75° and an appropriate choice of process conditions resulted in fairly acceptable bead profiles and joint properties.     

热处理对喷射成形7xxx系铝合金TIG焊接头组织与性能的影响

采用7055焊丝对喷射成形7xxx系铝合金进行TIG焊接,接头经450℃×1 h＋475℃×1 h的双级固溶后水淬,再进行120℃×24 h的时效处理后,焊缝组织均匀、晶粒有所长大,但没有出现过烧现象.经复合固溶处理后合金元素充分溶入基体,使得基体中的合金元素含量高于固溶前的含量,而固溶之前分布在晶界的合金元素经固溶之后降低了,固溶过程使合金成分区域趋于均匀化,后续的时效过程中过饱和固溶体析出强化相,使得接头强度得到了显著提高7,055达到了母材强度的65%,7475达到了母材强度的91%.结果表明,试验拟定的热处理工艺是合理的.     

工艺参数及焊接材料对T91/P91钢焊缝性能的影响

综合分析了手工电弧焊焊接过程中的预热温度、热处理温度、焊接线能量等主要工艺因素以及焊接材料对T91/P91钢焊缝性能的影响。     

工艺参数及焊接材料对T91/P91钢焊缝性能的影响

综合分析了手工电弧焊焊接过程中的预热温度、热处理温度、焊接线能量等主要工艺因素以及焊接材料对T91／P91钢焊缝性能的影响。     

Influence of the molybdenum content of high-alloy stainless steels and of the precipitation of intermetallic phases on pitting resistance in chloride-containing media

The influence of molybdenum on the resistance of stainless steels and nickel alloys (NiCrMoFe) to pitting corrosion is determined by means of electrochemical measurements (0.5 M NaCl/N2, 0…90°C) in both homogeneous and heterogeneous materials. As far as homogeneous materials are concerned, this influence is due to the inhibiting effect of molybdate formed at the interface passive layer/electrolyte and to a change in structure of the passive layer. The molybdate becomes effective as inhibitor of pitting corrosion only after the transpassive dissolution potential of molybdenum has been exceeded. Due to the precipitation of intermetallic phases, the pitting potential is shifted in cathodic direction. From a certain amount of precipitated intermetallic phases onward, the pitting potential remains constant. Consequently, the pitting potential is not dependent on the concentration of the alloying elements in the depleted matrix. Pitting corrosion preferably occurs at the phase boundaries intermetallic phase/depleted matrix and is due to lattice irregularities. Pit nucleation is observed at potentials at which the molybdate required for the inhibition of pitting corrosion has not yet been formed. Additions of molybdate to the electrolyte inhibit nucleation at the phase boundaries. Molybdenum segregates heavily in the weld microstructure of the afore-mentioned materials when compared with chromium. Pitting corrosion occurs at the dendrites that are poorer in molybdenum. A comparison of solution-annealed materials with different molybdenum contents shows that the molybdenum concentration of the dendrites imparts the same pitting resistance as is observed with solution-annealed materials with the same constant molybdenum content, respectively.     

Einfluß von Seigerungen auf das Korrosionsverhalten von austenitischem nichtrostendem Schweißgut

Influence of segregations on the corrosion behaviour of austenitic stainless weld metal Fully austenitic stainless weld metal on solidification acquires a segregation structure. The segregation takes place with the participation of the alloying elements responsible for the corrosion behaviour. Regions of low alloy content are preferentially attacked and microelements form between them and more corrosion resistant regions. The progress of corrosion is enhanced by lamellar segregation structures and is inhibited by cellular structures. The corrosion due to segregations is particularly pronounced when the resistance in one medium is a pronounced function of an alloying element prone to segregation. This is demonstrated on the example of weld metal X 2 CrNiSi 1815 having different Si contents. The effect of the base metal/weld metal macro-element is discussed. Corrosion due to segregation takes place only when the weld metal is subject to attack in the vicinity of its resistance limit.