低熔点高粘度拭焊用软钎料的研究

本文研究了不同成分含量的Pb—Sn—Cd系多元钎料合金熔点、强度。并对合金结晶过程中各相的形成、其数量关系及对合金粘度等性能的影响进行了分析讨论。成功地制得熔点低、强度高、粘度大的新型拭焊专用饮钎料合金。     

Ag-Cu-Sn-Cu_3P相图及该系钎料强韧机理初探

采用DTA，WDX和金相分析等方法研究测定了5％Sn－Ag－Cu－CU3P四元相图Cu角的部分变温截面；给出了该四元系五相平衡反应及各平衡相的成分；分析了该系钎料的强韧化机理．     

典型添加元素对Sn-Zn系钎料性能的影响

Sn-Zn钎料被认为是传统Sn-Pb共晶钎料的最佳替代合金之一,它以低廉的成本、较好的力学性能以及其共晶成分与Sn-37Pb钎料熔点相近等优点引起了人们的广泛关注,但其润湿性、抗氧化性、抗腐蚀性不够理想.阐述了Bi、A1、In、Ag、Cu及稀土元素(RE)等典型添加元素对Sn-Zn钎料各种性能的影响,以期为Sn-Zn钎料的研究开发和应用提供参考.     

镧对Sn3.5Ag0.5Cu钎料组织和性能的影响

运用莱卡显微镜、扫描电镜和能谱分析等仪器设备,研究添加微量La对Sn3.5Ag0.5Cu钎料组织性能的影响.结果表明,La能显著细化Sn3.5Ag0.5Cu钎料及其与Cu基体焊合后的IMC的显微组织,钎料剪切强度提高10.9%;键参数函数计算结果表明La具有"亲Sn"倾向,可降低IMC的长大驱动力.     

合金元素Cr,Al对Sn-Ag-Cu基无铅钎料高温抗氧化和润湿性的影响

研究了少量合金元素Cr，Al对Sn-3．0Ag-0．5Cu（305）无铅钎料高温抗氧化性的影响。钎料在液态下的表面颜色变化以及热重分析表明，Cr，Al能明显改善305合金钎料的抗氧化性能。通过合金元素Cr，AI的抗氧化机制和X射线衍射分析得出：Al和Cr在钎料表面形成致密氧化膜，形成“阻挡层”，抑制了钎料的氧化。同时也比较了合金元素Cr，Al对305钎料润湿性能的影响，结果表明：单独加Al不利于钎料的铺展，少量的Cr和Al同时加入对钎料的铺展没有太大的影响。实验证实：Cr和Al的共同作用明显提高了Sn-3．0Ag-0．5Cu钎料的高温抗氧化性，同时对钎料的润湿性也没有恶化作用。     

电子组装用含稀土无铅钎料研究

在电子产品的所有故障原因中,60%以上是由焊点失效所引起,而焊点的可靠性很大程度上取决于钎料的综合性能。因此,本文针对目前广泛应用的Sn3.8Ag0.7Cu(%,质量分数)无铅钎料,研究了添加微量的稀土元素Ce,Yb及Eu对Sn3.8Ag0.7Cu无铅钎料在Cu基板上的润湿性能的影响,同时对比分析了含不同稀土元素焊点的力学性能、微观组织和热疲劳性能。结果表明:添加单一稀土元素Ce,Yb及Eu后,Sn Ag Cu钎料的铺展面积显著增加,焊点的力学性能也得到不同程度的提高,提高幅度分别为12.7%,25.4%和18.0%。稀土元素Ce,Yb及Eu的添加细化了钎料的显微组织,焊点内部的共晶组织均匀分布在β-Sn基体中,且显微组织中的Cu6Sn5和Ag3Sn金属间化合物的尺寸也相应减小,这可能是含稀土Sn Ag Cu无铅焊点的力学性能高于Sn Ag Cu焊点的主要原因。此外,在热循环载荷下,发现稀土元素Ce,Yb及Eu可以显著提高Sn3.8Ag0.7Cu焊点的疲劳寿命。     

TiAl合金钎焊研究进展

TiAl合金钎焊因具有无气体杂质、对母材力学性能影响小、钎料成分易控制等突出优点而被广泛应用。概述了TiAl合金的发展历程及其组织特点,重点介绍了TiAl合金钎料种类以及钎焊工艺对焊接接头组织与性能的影响,最后指出TiAl合金钎焊技术的发展方向：加强焊接接头的动态试验研究,如疲劳性能、冲击韧性及蠕变试验;从扩散机理出发,首先进行热力学和动力学分析,再根据母材成分变化设计专用钎料;进一步扩展TiAl合金钎焊技术的应用领域。     

Zr对Ag-Cu-Ti钎料合金显微组织与力学性能的影响

通过非自耗电弧熔炼与氩气保护浇铸,制备Ag-50Cu-4Ti基钎料合金。采用差热分析(DSC)、X射线衍射(XRD)、显微组织观察及力学性能测试方法,研究Zr含量对基体钎料合金显微组织与力学性能的影响。结果表明,Zr含量的增加并不明显影响钎料合金的熔化温度,其熔点均为783℃左右。随Zr含量的提高,基体合金的显微组织发生明显变化,Zr的添加可降低基体合金中针状Cu3Ti相的体积分数与尺寸,促进弥散分布的(Cu,Ag)5(Ti,Zr)相形成,从而提高合金的维氏硬度与剪切强度。高温氧化实验表明,含Zr合金表现出相对基体合金更为优异的高温抗氧化性能。     

Sn1.0Ag0.5Cu和Sn3.0Ag0.5Cu钎料组织与性能对比研究

Sn3.0Ag0.5Cu无铅钎料已广泛应用于电子封装中,但是与传统的Sn Pb钎料相比,其抗冲击能力相对较差,且成本远远高于锡铅钎料。因此,为了改善抗冲击性能,降低钎料的成本,低银型无铅钎料成为研究热点。本文对比分析了Sn1.0Ag0.5Cu和Sn3.0Ag0.5Cu两种无铅钎料的润湿性及力学性能,同时研究了焊后和高温时效300 h后两种钎料焊点的显微组织。结果表明:随着Ag含量的增加,钎料的铺展面积显著增加,不同钎焊温度条件下,钎料的铺展面积随着钎焊温度的升高而明显增大。Sn3.0Ag0.5Cu钎料焊点的拉伸力和剪切力也明显高于Sn1.0Ag0.5Cu钎料,但随着时效时间的增加,高银型钎料的力学性能下降速度略高于低银型钎料。焊后两种钎料对应界面层为Cu6Sn5,经150℃时效300 h,界面金属间化合物的厚度随着时效时间的增加而增加。同时,界面层随着Ag含量的增加而增厚。     

合金元素对Sn-9Zn基无铅钎料润湿性和组织的影响

研究了分别添加混合轻稀土、磷和铋对Sn-9Zn共晶合金在铜基上的润湿性能及对钎料内部显微结构和钎料/铜界面的影响。研究结果表明:Bi、RE和P都能有效地改善Sn-9Zn基合金钎料在铜基上的润湿性;且添加RE和P对钎料/铜界面无明显的影响,也不改变Sn-9Zn钎料内部的扫把状共晶结构;而添加Bi促进了Sn-9Zn合金中锌的富集析出。     

Effect of Heat Input on Cleavage Crack Initiation of Simulated Coarse Grain Heat-affected Zone in Microalloyed Offshore Platform Steel

The combined effects of martensite-austenite(MA)constituent and pearlite colony on cleavage crack initiation in the simulated coarse-grained heat-affected zone(CGHAZ)of V-N-Ti microalloyed offshore platform steel under different heat inputs were investigated.The results of welding simulation,instrumented impact test,and quantitative analysis indicated that the size of the MA constituent decreased with the increase in cooling time,and by contrast,the size of the pearlite colony increased.According to Griffith theory,the critical sizes of cleavage microcracks were calculated.With the increase of cooling time,the calculated microcrack size could be characterized by the size of the MA constituent first,and then fitted with the size of the pearlite colony.Moreover,the calculated microcrack size variation was opposite to the microcrack initiation energy.This phenomenon is probably due to the combined effects of the MA constituent and pearlite colony with increasing the cooling time of the specimen′s temperature from800 to 500 ℃.     

Laser beam welding with filler metal

Laser beam welding generally does without the use of filler metal, in contrast to conventional welding processes. The use of filler metal in laser beam welding or in the combined GMA (g as-m etal-a rc) - laser beam - hybrid welding process widens the field of application for laser beam welding. The main advantages worthy of mention include, primarily, a greater weld gap bridging ability and a metallurgical influence on the weld metal. Based on the current state of knowledge, this article gives a few examples of different materials and material combinations the limited weldability of which is broadened when filler metal is used with laser beam welding. Listed as examples are low-alloy steels with partly elevated carbon contents, duplex steels, and the material combinations of steel/cast iron and austenite-ferrite joints. Besides laser beam welding with filler metal wire, examples of the combined GMA-laser hybrid welding process are also described.     

The structure and properties of aluminum alloys produced by mechanical alloying: Powder processing and resultant powder structures

Mechanical alloying of two aluminum alloy powders to form composite A1-A1₂O₃ powders has been studied. Changes in powder microstructure with processing are reported and interpreted. Mechanical alloying proceeds by the continual cold welding and fracturing of the constituent powder particles when subjected to the large compressive forces of a high speed mill. A suitable organic surfactant must be added so that a balance between cold welding and fracturing is obtained. The organic surfactant is embedded and finely distributed in the powder particles during mechanical alloying and is converted to discrete A1₄C₃ particles after hot pressing. The establishment of steady state processing conditions, characterized by equiaxed powder particles, a constant particle size distribution and a saturation hardness, is found to depend on the size distribution of the initial powders. The oxide particles formed and distributed during mechanical alloying are equiaxed, small (30 nm) and homogeneously distributed with a volumetric center to center distance of about 60 nm. Formerly Graduate Research Assistant in the Department of Materials Science and Engineering at Stanford.     

电渣焊在制作箱型构件中的应用

箱型截面构件壁板与隔板电渣焊时,易产生壁板烧穿和焊缝未熔合现象,通过焊接熔透性工艺试验,调控焊接工艺参数,优选装配坡口尺寸,提高衬条及隔板加工精度,保证了电渣焊质量和焊接效率的提高.     

Solidification of an alloy 625 weld overlay

The solidification behavior (microsegregation, secondary phase formation, and solidification temperature range) of an Alloy 625 weld overlay deposited on 2.25Cr - 1Mo steel by gas metal arc welding was investigated by light and electron optical microscopy, electron microprobe, and differential thermal analysis techniques. The overlay deposit was found to terminate solidification at ≈ 1216 °C by aγ/Laves eutectic-type reaction. The Laves phase was highly enriched in Nb, Mo, and Si. The solidification reaction and microsegregation potential of major alloying elements in the overlay deposit are compared to other Nb-bearing Ni base alloys and found to be very similar to those for Alloy 718. Solidification cracks observed in the overlay were attributed to the wide solidification temperature range (≈170 °C) and formation of interdendritic (γ+Laves) constituent. Reasonable agreement is obtained between the calculated and measured volume percent (γ+Laves) constituent with the Scheil equation by treating the overlay system as a simpleγ-Nb “binary” and using an experimentally determinedk ^Nb value from electron microprobe data.     

线能量对插销临界应力的影响

本文用Ar+20％CO_2气体保护焊方法对15MnVN钢进行插销试验,试验结果表明,焊接线能量在15～40 kJ/cm范围内,插销试验的临界断裂应力高于15MnVN钢的屈服强度;也高于用J507焊条及J557MoV焊条电弧焊15MnVN钢插销试验的临界断裂应力。观察金相试样得知,15MnVN钢焊接热影响区组对焊接线能量比较敏感,脆硬马氏体及粗大铁素体的产生都会降低插销试样的临界断裂应力。为使15MnVN钢焊接热影响区获得最佳组织和最好的抗裂性能,焊接线能量应选择20～30 kJ/cm。     

Inclusion Characteristics and Acicular Ferrite Nucleation in Ti-Containing Weld Metals of X80 Pipeline Steel

X80 steel weld metals with Ti contents of 0.003 to 0.13 pct were prepared by the single-pass submerged-arc welding process. The effects of Ti content in weld metals on the constituent phases of inclusions and chemical compositions of the constituent phases, as well as the potency of acicular ferrite (AF) nucleation on the inclusions were investigated. Moreover, the crystallographic orientation relationship between the AF and inclusion was examined. The results show that with an increase in Ti content, the primary constituent phases of the inclusions change from the (Mn-Al-Si-O) compound to a mixture of spinel and pseudobrookite solid solutions, and eventually to pseudobrookite. The spinel solid solution is characterized by the MnTi₂O₄ constituent. Compared to pseudobrookite, spinel has a lower Ti concentration, but a significantly higher Mn content. In the case of the presence of a considerable amount of spinel, the Mn element is enriched strongly in the inclusions, resulting in the development of a Mn-depleted zone (MDZ) in the matrix around the inclusions, which enhances the driving force for AF formation. AF shows the Baker–Nutting orientation relationship with MnTi₂O₄. The formation of MDZ and the presence of the Baker–Nutting orientation relationship promote the ability of inclusions to nucleate the intragranular AF.     

700MPa级高强度调质钢板焊接性能研究

从低成本700 MPa级调质中厚钢板的焊接性能着手,分析了母材的成分、组织及性能特点,研究了其焊接冷裂纹敏感性、焊接过程中的热输入量以及焊后热处理过程对试验钢焊接接头组织和性能的影响。结果表明,针对50 mm厚的700 MPa级高强度调质钢板,在中等拘束条件下,采用BHG-4M焊丝富氩混合气体保护焊、预热100℃的工艺进行焊接可以防止冷裂纹产生;在苛刻拘束条件下,最低预热温度在120℃以上才能防止裂纹产生;试验钢对焊接工艺规范有较强的适应性,焊接热输入量在8.85~24.17 kJ/cm范围内变化时,试验钢焊接接头的综合力学性能保持在较高水平。     

不同5xxx系焊丝对5182-H111组织和性能的影响

使用3种焊丝ER 5183、ER 5356、ER 5554对6mm 5182-H111铝合金板材进行半自动MIG焊对接试验,通过对焊接接头进行力学性能试验、显微硬度测试及金相组织的观察,探究3种焊丝对5182-H111铝合金组织和性能的影响。结果表明,使用3种焊丝所焊接头中,ER 5183及ER 5356接头抗拉强度均大于ISO 15614-22005要求的焊缝接头系数(1.0),而ER 5554接头焊缝系数仅为0.949;3种焊丝所焊接头硬度均在焊缝区及热影响区有所降低,其中ER 5356所焊接头焊缝强度较其他两种焊丝焊缝区硬度高,为85.5HV;3种焊丝所焊接头组织形貌相近,均存在β(Mg2Al3)强化相,但由于ER 5183与ER 5356焊丝中含有更多的Mg,因此生成了更多的β(Mg2Al3)相,使得焊缝组织更加致密。     

不锈钢厚壁管道的焊接实践

详细介绍材质为X 6CrNiMoTi17-12-2的不锈钢厚壁管道焊接方法,重点叙述在焊接过程中需特别注意的关键环节,以及焊接实际操作要点。