钛基钎料的不同制备状态对钎焊接头显微组织的影响

使用同等成分的Ti-Zr-Cu-Ni晶态钎料和非晶态钎料进行TiAl合金真空钎焊,研究了钎料的不同制备状态对TiAl合金钎焊接头显微结构的影响。通过对比分析得出。2种钎焊接头区域都可分为α-Ti相区、α2-Ti3Al相区、不规则析出区、富Cu,Ni相区、残余钎料区;非晶态钎焊接头的富Cu,Ni相区的相组织为(Ni,Cu)3 Ti固溶体,残余钎料区的相组织为(CuTi),(NiTi3)固溶体,而晶态钎焊接头对应区域的相组织为(Ni,Cu)Ti和α-Ti固溶体。     

PLC控制钎焊Cu/Al焊接接头的组织与性能研究

采用PLC控制固定间隙超声波辅助Cu/Al异质金属的钎焊工艺,在钎焊温度为380、420和460℃下制备Al/Zn-3Al/Cu钎焊接头,观察了不同温度超声钎焊时接头的显微组织与力学性能变化。结果表明,当钎焊温度为380℃时,钎缝层由Zn-Al共晶、α-Al树枝状晶和CuZn_5相组成;当钎焊温度为420和460℃时,钎缝层由α-Al树枝状晶、CuZn_5相和Al_(4.2)Cu_(3.2)Zn_(0.7)相组成;在钎焊温度为420℃时,金属间化合物层厚度为1.9μm,扩散层厚度1.3μm,整个界面层厚度为三种钎焊温度下的最低值,此时取得钎焊接头抗拉强度最大值。     

微机控制钎焊Cu/Al焊接接头的组织与性能

采用微机控制固定间隙超声波辅助汽车零部件焊接中Cu/Al异质金属的钎焊工艺,在钎焊温度为380、420和460℃时制备Cu/Zn-3Al/Al钎焊接头,观察了不同温度超声钎焊时接头的显微组织与力学性能变化。结果表明,当钎焊温度为380℃时,钎缝层由Zn-Al共晶、α-Al树枝状晶和CuZn5相组成;当钎焊温度为420和460℃时,发现钎缝层由α-Al树枝晶、CuZn5相和Al4.2Cu3.2Zn0.7相组成;在钎焊温度为420℃时,金属间化合物层厚度为1.9μm,扩散层厚度为1.3μm,整个界面层厚度为3种钎焊温度下的最低值,此时钎焊接头的抗拉强度最大。     

真空钎焊工艺对Al_2O_3陶瓷/304不锈钢接头成形的影响

采用Ag-Cu-Ti钎料对Al_2O_3陶瓷与304不锈钢进行了不同工艺参数下的真空钎焊连接试验。通过SEM、EDS、XRD方法分析了钎焊接头的显微组织和界面反应产物,研究了钎焊温度和保温时间对钎焊接头组织和裂纹的影响。结果表明,Al_2O_3/304接头钎缝分为3个反应区,分别是靠近陶瓷的反应层,由Ti O反应层和Ti3Al反应层组成;钎缝区,由Ag(Cu)固溶体、Cu(Ag)固溶体和Ti Fe_2组成;靠近不锈钢的Ti Fe_2+Ti O反应层。随着钎焊温度升高,保温时间的延长,接头钎缝中Ti Fe_2数量增加,尺寸增大,这降低了通过塑性变形缓解接头残余应力的能力,同时陶瓷侧界面反应层增厚。这些使得接头陶瓷的裂纹现象越严重。     

镁/钢激光-MIG熔钎焊接头微观组织分析及性能研究

在钢表面电镀20μm的纯铜,以AZ31B镁合金焊丝作为填充材料,采用激光-MIG熔钎焊连接AZ31B镁合金和Q235钢,研究不同参数下熔钎焊接头宏观形貌、微观组织及力学性能。结果表明:在合适的焊接参数下,激光-MIG熔钎焊能得到较好的焊缝表面成型。焊接速度为6 mm/s时,钢侧界面区有3～5μm的界面反应层,且为双层结构。通过EDS和XRD分析,钢侧反应层主要是Al Fe3、Al2Cu3化合物,靠反应层的焊缝区是α-Mg固溶体和Mg2Cu、Al CuMg化合物,焊缝中部为是α-Mg固溶体和Al12Mg17化合物。在最优焊接工艺下,抗拉强度最高,达到188.97 MPa。     

Al-Si-Cu-Zn急冷钎料钎焊铝及铝合金的界面结构及强度

采用Al70Si7.5Cu20Zn2.5和Al65Si10Cu20Zn5两种急冷钎料钎焊L2纯铝和6063铝合金,研究钎焊接头的界面微观结构和力学性能.结果表明,急冷钎料钎焊接头由母材、界面区和钎缝中心组成.界面区为αAl固溶体,钎缝中心组织为αAl固溶体 θ(Al2Cu)相 Si相.采用Al65Si10Cu20Zn5急冷钎料钎焊的接头抗剪强度均高于Al70Si-7.5Cu20Zn2.5急冷钎料钎焊的接头强度;匹配氯化物钎剂钎焊的接头强度均高于氟化物钎剂.在相同的工艺条件下,采用急冷钎料钎焊的L2纯铝接头,其抗剪强度都明显高于相应的常规钎料,其增加值在40%左右.     

铝/钢CMT熔-钎焊接头微观组织及力学性能研究

使用CMT熔-钎焊技术以ER4043(A1Si5)焊丝作为填充金属对6061铝合金及表面预涂特种钎剂的304不锈钢异种材料进行了焊接。使用SEM、EDS、XRD及显微硬度试验对焊接接头的显微组织及力学性能进行了研究。结果表明:铝和不锈钢的CMT熔-钎焊缝成形良好,且熔化的焊丝向不锈钢侧铺展比较理想。焊接接头由热影响区、熔合区及钎焊界面层组成。热影响区及熔合区的组织为α-Al固溶体和Al-Si共晶相;在钎焊界面层形成一定厚度的化合物层,主要为FeAl_2相及Al_(0.5)Fe_3Si_(0.5)三元相。拉伸断裂于焊缝/钎焊界面层,断口为脆性断裂,接头强度为84.1MPa。     

0.4mm不锈钢单边薄板钎焊工艺及组织分析

采用BNi-2镍基钎料对不锈钢单边薄板(厚度小于0.4 mm)真空钎焊,运用金相分析方法对钎焊接头的微观组织特征进行了研究。试验表明:在真空钎焊过程中,钎料和母材中元素扩散显著;钎缝组织由两部分组成:一部分是接近母材钎缝区一侧的固溶体组织,另一部分是位于中部的化合物相组织。不锈钢单边薄板的焊接接头组织均匀,钎料与母材之间得到了良好的冶金结合,从而得到满足要求的焊接接头。     

药芯铝钎料钎焊Cu/Al异种金属接头的力学性能及反应物

以3种药芯铝钎料对Cu/Al异种金属进行了火焰钎焊,研究了钎焊接头的力学性能及反应物.通过测试和分析3种钎焊接头的强度、组织和显微硬度,从中选取综合性能较优的试样ZAAg2;采用扫描电镜(SEM)、X射线衍射仪(XRD)、X射线能谱仪(EDS)等进一步分析该钎焊接头的组织及反应物.结果表明:性能较优钎焊接头ZAAg2接头强度高达75 MPa,接头的主要断裂形式为沿晶脆性断裂,断裂主要产生在CuAl,CuAl2,Al4Cu9等脆性组织与α - Al基体的界面处.钎料与母材发生界面反应,钎缝中靠近铝侧生成α-Al固溶体,靠近铜侧生产CuAl,CuAl2,Al4 Cu9等脆性相.     

TC4/TNM钎焊接头界面组织及性能

采用Ti-25.65Zr-13.3Cu-12.35Ni-3Co-2Mo(wt.%)非晶箔带钎料在900 ℃~1020 ℃/10 min工艺下真空钎焊连接TC4和TNM合金,并系统研究了TC4/TNM钎焊接头的界面组织和形成机理以及钎焊温度对界面组织和剪切强度的影响规律。结果表明：钎焊温度900～980 ℃时接头的组织为TC4/细小网篮状(α+β)-Ti/γ-(Ti,Zr)2(Cu,Ni) + α-Ti/Ti3Al/TNM,随钎焊温度升高,钎缝中硬脆的γ相减少、韧性的α-Ti增加。钎焊温度1000 ℃和1020 ℃时,接头的界面反应层由三层演变成两层且对应的物相分别是韧性差的粗针状(α+β)-Ti和Ti3Al,粗针状(α+β)-Ti随温度升高进一步粗化。钎焊接头剪切强度随温度升高先增加后减小,钎焊温度980 ℃时剪切强度达到最大值494.83 MPa。剪切测试的钎焊接头均脆性断裂于TNM侧的钎缝中。     

Formability of AA5052/polyethylene/AA5052 sandwich sheets

The formability of AA5052/polyethylene/AA5052 sandwich sheets was experimentally studied. Three kinds of AA5052/polyethylene/AA5052 sandwich specimens with different thicknesses of core materials were prepared by the hot pressing adhesive method. Then, the uniaxial tensile tests were conducted to investigate the mechanical properties of AA5052/polyethylene/ AA5052 sandwich sheets, and the stretching tests were carried out to investigate the influences of polymer core thickness on the limit dome height of the sandwich sheet. The forming limit curves for three kinds of sandwich sheets were obtained. The experimental results show that the forming limit of the AA5052/polyethylene/AA5052 sandwich sheet is higher than that of the monolithic AA5052 sheet, and it increases with increasing the thickness of polyethylene core.     

Development and analysis of frits for enamelling AA2024, AA6082 and AA7075 aluminium alloys

This study reports the development of frits with different composition, time, and firing temperature for mitigating the corrosion of AA2024, AA6082, and AA7075 aluminium alloys in chloride-containing solutions. The melting points of the frits were determined using a heating microscope, while the thermal expansion was measured using dilatometry. Several frits were prepared, of which seven were coated on AA2024, AA6082 and AA7075 aluminium alloys. The corrosion resistance of the coated samples was tested in 5 wt% NaCl solution at 25°C using potentiodynamic curve measurements. The corrosion resistance of the coated samples increased compared with the respective uncoated aluminium alloys. The composition and in-depth homogeneity of the best-performing coated samples were confirmed using a gas cluster ion beam sputtering source associated with X-ray photoelectron spectroscopy analysis. Furthermore, O₂⁺ sputtering was performed in association with time-of-flight secondary ion mass spectrometry to describe the three-dimensional composition of the frits.     

Corrosion behaviour of brazed multilayer material AA4343/AA3003/AA4343: Influence of coolant parameters

This paper is the second part of a work devoted to corrosion in brazed AA4343/AA3003/AA4343 materials on the water side of automotive heater cores. In the first part of the study [S. Tierce, N. Pébère, C. Blanc, C. Casenave, G. Mankowski, H. Robidou, Electrochim. Acta 52 (2006) 1092], corrosion initiation in the surface layer (i.e. the residual cladding) has been investigated. It has been associated to defective sites in the passive film covering the alloy. The defective sites are linked to α-Al(Mn,Fe)Si particles built up during brazing process. Interactions between α-Al(Mn,Fe)Si particles and the matrix are responsible for the observed behaviour. The present study focuses on the propagation of corrosion through the material in neutral water–ethylene glycol mixtures with and without chlorides. Comparison of the electrochemical behaviour of the three layers of the brazed material (i.e. the residual cladding, the “band of dense precipitates (BDP)” and the core material) revealed that the residual cladding was nobler than the BDP and the core material and thus that the corrosion should propagate through the inner layers due to galvanic coupling: the inner layers constitute the anode and the residual cladding the cathode. Increasing the ethylene glycol content in the water–ethylene glycol mixture decreased the rate of consumption of the materials whereas addition of chloride ions increased it. Mass variation measurements of brazed material in different solutions containing the degradation products of ethylene glycol showed that only glycolate ions had a slight detrimental effect. Corrosion tests performed in heater core tubes allowed the propagation mechanisms to be confirmed.     

The effect of inhibitor structure on the corrosion of AA2024 and AA7075

A range of structurally-related compounds were tested for their capacity to inhibit corrosion on aluminium alloys AA2024-T3 and AA7075-T6 in 0.1 M NaCl solution. It was found that the thiol group, positions para- and ortho- to a carboxylate, and substitution of N for C in certain positions strongly inhibited corrosion. The hydroxyl group was slightly inhibitive, while the carboxylate group provided little or no corrosion inhibition on its own. In several cases, different activities were found on the different alloys, with some compounds (particularly thiol-containing compounds) being more effective on AA2024 than on AA7075.     

AA5083铝合金表面处理对AA5083/低温胶胶接性能的影响

目的为适应LNG船运输液化天然气时的低温工作环境,选择AA5083铝合金和外围保温材料,通过低温胶胶接的方式进行液货维护系统内部结构的搭建,保证满足基本强度要求的同时,降低生产成本。方法对AA5083铝合金进行喷砂和阳极氧化处理,对其表面形貌、表面粗糙度、表面能以及与低温胶的接触角进行表面性能表征,同时进行25、0、-60、-120℃四种不同温度下的单搭剪切力学性能测试,研究揭示不同表面处理方法对AA5083/低温胶胶接强度的影响。结果与AA5083铝合金原始试样对比,表面处理后的铝合金表面粗糙度变大,表面能升高,与低温胶的接触角变小,胶接接头强度显著提升,其中,阳极氧化后试样的胶接强度在0℃达到最大,为29.80 MPa,比原始试样提升了128.18%,比喷砂试样提升了29.90%。结论结合表面性能表征以及低温下的单搭剪切试验结果,喷砂和阳极氧化均能提高AA5083铝合金与低温胶的粘结强度,而且阳极氧化后的AA5083铝合金具有较好的综合性能。     

Investigation of the Friction Stir Lap Welding of Aluminum Alloys AA 5182 and AA 6022

Friction stir lap welding of the similar and dissimilar aluminum alloys is investigated. AA 5182 and AA 6022 aluminum alloys (the widely used aluminum alloys for automobile applications) are selected for the feasibility studies. The friction stir lap welding shows that the placement of the aluminum alloys in the different orders over each other affect the final weld quality and its mechanical properties. The welding parameters such as rotational and traverse speeds and the penetration depth are key factors to affect the micro-structure soundness. The mechanical and the micro-structural characterization is performed on the joints formed with varying welding parameters and from the different order of placement of the AA 6022 and the AA 5182 sheets. The weld failure occurs on the advancing side during the peel tests indicating that the retreating side is relatively stronger. Measured temperatures indicate that the advancing side has higher developed temperature during the course of welding compared to the retreating side.     

Mechanical properties and microstructure evolution in incremental forming of AA5754 and AA6061 aluminum alloys

This study performs single point incremental forming (SPIF) on two aluminum alloys (i.e. AA5754 and AA6061), and analyzes their post forming mechanical properties and microstructure evolution. The forming parameters namely wall angle (35°–55°), feed rate (1–4 m/min), spindle rotational speed (50–1000 r/min), and lubricant (grease and hydraulic oil) are varied to probe detailed processing effects. The pre- and post-SPIF mechanical properties and microstructures are characterized by conducting tensile tests and optical microscopy, respectively. It is shown that an increase in the wall angle, feed rate and rotational speed causes microscopic variations in the alloys such that the grains of AA5754 and the second phase particles of AA6061 elongate. As a result, the ultimate tensile strength of the formed parts is increased by 10% for AA5754 and by 8% for AA6061. And, the ductility of AA5754 is decreased from 22.9% to 12% and that of AA6061 is decreased from 16% to 10.7%. Regarding the lubricant effect, it is shown that the mechanical properties remain insensitive to the type of lubricant employed. These results indicate that SPIF processing modifies the microstructure of Al alloys in a way to enhance the strength at the cost of ductility.     

Electrical conductivity field analysis for evaluation of FSW joints in AA6013 and AA7075 alloys

To fully characterize Friction Stir Welding several techniques are required, mainly destructive, as hardness or metallographic testing. However, there is still a need for developing dedicated methods, preferably non-destructive. Electrical conductivity, based on a different physical principle, may constitute an alternative. The present study aims to characterize the electrical conductivity in friction stir welds and to investigate the correlation between this and the hardness observed in different regions of a weld. An eddy current planar probe was used for the measurements at different depths. For this, welded samples were machined in steps and in ramp and scans along orthogonal axis were performed. The results were correlated with the microstructural modifications. A close match between the electrical conductivity field and the microstructure was observed. A good correlation with hardness was noticed, suggesting that the non-destructive test has the potential to complement or substitute destructive methods as hardness tests.