ANALYSIS OF HOT IMPREGNATED Al-Si COATINGS

The microstructure and chemical composition of the hot impregnated Al-Si coating on 08Alsteel sheet were analysed by SEM,EPMA and X-ray diffraction.The coating consists ofthree parts:the outer is an α-Al solid solution enriched Si and γ-(Fe,Al,Si)phases;the in-termediate FeAl_3 and Fe_2Al_5 phases mainly and the inner neighbouring the substrate mainlyFe_2Al_5 phase.     

Evolution Behavior of γ-Al_(3.5)FeSi in Mg Melt and a Separation Method of Fe from Al–Si–Fe Alloys

The recycling of high Fe-content Al–Si alloys is a green industry. Eliminating the harmful effect of Fe,achieving the separation of Al and Fe is one of the key problems. Different from traditional methods for iron removal, a novel method using magnesium melt to separate Al and Fe is proposed. By introducing Al–14 Si–5 Fe alloy into Mg melt, it was found that the γ-Al_(3.5)FeSi phase evolves to Al_3SiFe_(3.5) and Al_5Fe_2 through the melting and solidification process.Compared with the primary Al-rich γ-Al_(3.5)FeSi phase, the formation of Fe-rich Al_3Si Fe_(3.5) is quite beneficial for the separation of Al and Fe. Mg–Si–Al and Mg–Si–Fe alloys can be obtained at the top and bottom of the cooled ingot,respectively. The results in this study provide meaningful suggestions for recycling scrap Al–Si–Fe materials.     

Microstructure and Mechanical Properties of Galvanized Steel/AA6061 Joints by Laser Fusion Brazing Welding

Laser fusion brazing welding was proposed.Galvanized steel/AA6061 lapped joint was obtained by laser fusion brazing welding technique using the laser-induced aluminium molten pool spreading and wetting the solid steel surface.Wide joint interface was formed using the rectangular laser beam coupled with the synchronous powder feeding.The result showed that the tiny structure with the composition of a-Al and Al–Si eutectic was formed in the weld close to the Al side.And close to the steel side,a layer of compact Fe–Al–Si intermetallics,including the Al-rich FeAl3,Fe2Al5 phases and Al–Fe–Si s1 phase,was generated with the thickness of about 10–20 lm.Transverse tensile shows the brittlefractured characteristic along to the seam/steel interface with the maximum yield strength of 152.5 MPa due to the existence of hardening phases s1 and Al–Fe intermetallics.     

Joint Characteristics and Corrosion Properties of Bypass-Current Double-Sided Arc-Welded Aluminum 6061 Alloy with Al–Si Filler Metal

Sheets of aluminum 6061 alloy were welded using bypass-current double-sided arc welding with Al–Si filler wire to investigate the effect of Al–Si intermetallic compounds on the microstructure, microhardness and corrosion behavior of weld joint. Experimental results indicated that the Al_(4.5)FeSi phase in the topside of the weld joint was finer than that in the backside and newly formed phase of Al_(0.5)Fe_3Si_(0.5)was observed in the backside. The formation of reinforcing phases of Al–Fe–Si in the weld improved the microhardness of the weld by about 18%. The corrosion resistance of the weld zone was greater than that of the base metal, while the corrosion current displayed opposite, and the corrosion resistance of the weld region was better than that of the base metal.     

Comparative Study of Bypass-Current MIG Welded–Brazed Aluminum/Galvanized Steel and Aluminum/Stainless Steel

A bypass-current metal inert-gas welding–brazing technology has been developed to join aluminum/galvanized steel and aluminum/stainless steel. Microstructure, intermetallic compounds and hardness distribution of the joints were studied by optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis and microhardness tests. Comparative study on both types of joints was carried out. During aluminum to galvanized steel assembling, finer seam was obtained under a more stable process. A uniform interfacial reaction layer with a thickness of 2–4 μm was formed. During aluminum to stainless steel assembling, an uneven interfacial reaction layer with a thickness of 5–45 μm was formed. Intermetallic compounds at the interface of aluminum/galvanized steel were identified as Fe–Al–Si–Zn complex phases, while Fe–Al–Cr–Ni complex phases were found at the aluminum/stainless steel interface.Microhardness of interfacial layer increases rapidly within reaction layer due to possible brittle intermetallic compounds.     

Microstructural evolution of direct chill cast Al-15.5Si-4Cu-1Mg-1Ni-0.5Cr alloy during solution treatment

Heat treatment has important influence on the microstructure and mechanical properties of Al-Si alloys. The most common used heat treatment method for these alloys is solution treatment followed by age-hardening. This paper investigates the microstructural evolution of a direct chill (DC) cast Al-15.5Si-4Cu-1Mg-1Ni-0.5Cr alloy after solution treated at 500, 510, 520 and 530℃, respectively for different times. The major phases observed in the as-cast alloy are α-aluminum dendrite, primary Si particle, eutectic Si, Al7Cu4Ni, Al5Cu2Mg8Si6, Al15(Cr, Fe, Ni, Cu)4Si2 and Al2Cu. The Al2Cu phase dissolves completely after being solution treated for 2 h at 500℃, while the eutectic Si, Al5Cu2Mg8Si6 and Al15(Cr, Fe, Ni, Cu)4Si2 phases are insoluble. In addition, the Al7Cu4Ni phase is substituted by the Al3CuNi phase. The α-aluminum dendrite network disappears when the solution temperature is increased to 530℃. Incipient melting of the Al2Cu-rich eutectic mixture occurrs at 520℃, and melting of the Al5Cu2Mg8Si6 and Al3CuNi phases is observed at a solution temperature of 530℃. The void formation of the structure and deterioration of the mechanical properties are found in samples solution treated at 530℃.     

Analysis of Intermetallic Phases Formed on Surface Vapor Oxidized H13 Hot Work Steels in Molten Aluminum

In this paper, the author dipped surface vapor oxidized H13 steel specimens into 700℃ molten aluminum liquid for a certain period of time. Analyze the intermetallic phases formed on the H 13 samples surface with optical microscope and X-ray diffraction method. The observation of immersion test sample‘s cross-section shows that Fe304 film will protect die substrate from molten aluminum erosion. The identification of the intermetallic phases reveals that they consist of 2 parts, which is named as the composite layer and the compact layer. Further investigations are made in order to know the phase constituents of the 2 layers, they are Al8Fe2Si (outer composite layer), (AlCuMg) and Al5Fe2 (compact layer), respectively. The experimental results show that on the same specimen, a convex surface with bigger radius of curvature is more likely to be molten and the melting loss speed is also faster than a flat and smooth surface. The thickness of compact layer on a smooth surface is much bigger than that of the convex surface. Therefore, the author supposes the compact layer is favorable in stabilizing the die surface material from further melting loss, as their formation on the die surface, the melting loss speed will decrease.     

Influence of Si content and heat treatment on microstructure of Al-Fe-Si alloys

The effect of Si addition and heat treatment on the Al-5wt.%Fe al oy has been investigated by OM, SEM-EDS and XRD. The results show that the Si plays a significant role in refining the primary Al3Fe phase. It was found that the addition of 3.0wt.% Si made the al oy present the finest and wel -distributed primary Al3Fe phase, but the Al3Fe phase almost disappeared when 5wt.% Si was added. With further increase in the Si content, some Fe-rich phases appeared in the inter-grains and coarsened. In addition, the heat treatments exert a significant impact on the microstructural evolution of the Al-5wt.%Fe-5wt.%Si al oy. After heat treatment for 28 hours at 590 oC, the coarse platelet or blocky Fe-rich phase in Al-5wt.%Fe-5wt.%Si al oys was granulated; the phase transformation from metastable platelet Al3FeSi and blocky Al8Fe2Si to stable Al5FeSi had occurred. With the extension of heat treatment, the Si phase coarsened gradual y.     

Microstructure characteristics of dissimilar metal weld between aluminum alloy and brass

Dissimilar metal joining between 5A02 aluminum alloy and H62 brass sheets was conducted by gas tungsten arc welding with Zn-15% Al and Al-12% Si flux-cored filler wires. The microstructure in the weld and distribution of major alloying elements in the intelfacial layer were examined, and the tensile strength of the resultant joints was measured. Pores appeared in the weld made with Zn-15% Al flax-cored filler wire, the interracial layer mainly consisted of AlCu phase, and the specimens fractured through the weld with tensile strength of 129 MPa. When Al-12% Si flux-cored filler wire was used, Cu diffused into the weld and Al2 Cu phase formed, and the specimens fractured along the interfacial layer with tensile strength of 122 MPa.     

陶瓷/AgCuTi/不锈钢钎焊连接界面组织与结构

采用Ag-Cu-Ti钎料对日用陶瓷与1Cr18Ni9Ti不锈钢进行了钎焊连接.用扫描电镜、能谱仪以及X射线衍射仪对接头的微观组织形貌、特征点的成分以及钎焊接头的物相等进行了分析研究.结果表明,接头界面处形成了多种化合物,包括TiO,TiSi_2,Ti_5Si_3和Fe_2Ti.当温度为850℃,保温时间为5 min时,接头界面结构为1Cr18Ni9Ti不锈钢/Fe_2Ti/Ag[s,s]+Cu[s,s]+Fe_2TiO+Ti_5Si_3+TiSi_2/陶瓷.当钎焊温度较高或保温时间较长时,界面反应层厚度增加,界面中基体相Ag[s,s],Cu[s,s]所占比例显著减小.

Abstract：

Domestic ceramics and lCrl8Ni9Ti stainless steel were brazed using Ag-Cu-Ti filler metal. Microstructure, the component of characteristic points and the phases of brazing joints were studied by scanning electronic microscopy ( SEM) , energy distribution spectrometer (EDS) and x-ray diffraction (XRD). The results show that several kinds of intermetallics such as TiO_2, TiO, TiSi_2 , Ti_5 Si_3 and Fe_2 Ti were formed. The interfacial structure of joints is 1Cr18Ni9Ti stainless steel/Fez Ti/Ag[ s, s] + Cu[s,s] + Fe_2Ti/TiO_2 + TiO + Ti_5Si_3 + TiSi_2/ceramics when brazing temperature and time are 850 ℃ and 5min, respectively. The depth of interfacial reactive layer increases and the ratio of matrix phase Ag [ s, s ], Cu [ s, s ] which are in the middle of interface reduces evidently as brazing temperature is very high or holding time is very long.     

铝合金/不锈钢预涂层钨极氩弧熔钎焊接头的特性

通过在不锈钢表面预涂钎剂层,采用铝硅共晶钎料实现铝合金/不锈钢TIG熔钎焊连接,获得具有熔焊与钎焊双重性质的对接接头,运用OM、SEM、EDS分析接头的微观组织及成分,通过拉伸实验评定接头的力学性能.结果表明:铝母材局部熔化,与液态钎料混合后凝固形成焊缝,焊缝组织主要由α(Al)基体和在晶界析出的Al-Si共晶相组成;不锈钢不发生熔化,液态钎料与不锈钢在界面反应形成不均匀分布的金属间化合物层,最大厚度不超过10 μm,界面上部金属间化合物较厚,呈锯齿状,主要相成分为α(τ5)-Al7.4Fe2Si;界面下部金属间化合物较薄,呈细须状,由α(τ5)-Al7.4Fe2Si+α(Al)混合相构成;接头的平均抗拉强度为90.6 MPa,焊缝/不锈钢界面下部为连接的薄弱环节,成为断裂的起始位置.     

INHIBITORY ACTION OF Si ON GROWTH OF INTERFACIAL COMPOUND LAYER DURING HOT－DIP ALUMINIZING

对添加２ａｔ．－％Ｓｉ后热浸镀Ａｌ钢带界面化合物层的结构和组成进行了实验研究。结果发现，Ｓｉ在界面化合物层区产生富集，界面化合物具有Ｆｅ_２Ａｌ_５相的结构，其化学式可写成Ｆｅ_２（ＡｌＳｉ）_５．认为Ｓｉ的作用在于填充Ｆｅ_２Ａｌ_５相中的原子空位，阻碍Ａｌ的扩散，使界面化合物层厚度大大下降．     

焊丝成分对SiCp/6061 Al复合材料MIG焊焊缝组织及性能的影响

采用Al-Mg及Al-Si两种焊丝分别对SiCp/6061Al复合材料进行了MIG焊及脉冲MIG焊,利用光学显微镜、电子显微镜及MTS-810试验机对焊缝的组织及性能进行了分析.结果表明,采用Al-Mg焊丝焊接时,无论是MIG焊还是脉冲MIG焊,熔池中Al-SiC间的界面反应程度均较大,生成了较多的针状Al4C3,且Al4C3的尺寸较大.采用Al-Si焊丝时,MIG焊熔池中的界面反应程度显著降低,仅生成了少量尺寸较小的针状Al4C3;而采用Al-Si焊丝的脉冲MIG焊焊缝中没有发现针状Al4C3.同时,利用Al-Si焊丝可有效地防止焊缝熄弧处的宏观结晶裂纹.力学性能试验表明,采用同样焊丝时,脉冲MIG焊接头的强度及伸长率比MIG焊接头的高,而用Al-Si焊丝焊接的接头强度比用Al-Mg焊丝焊接的接头强度高.     

热浸镀铝硅镀层微观组织结构表征

目的 研究热成形钢热浸镀铝硅镀层的微观组织与物相组成.方法 利用扫描电镜(SEM)和能谱仪(EDS)分析铝硅镀层表面与截面的微观组织形貌与成分,利用X射线衍射(XRD)和电子背散射衍射技术(EBSD)分析铝硅镀层的物相组成与比例.结果 热浸镀铝硅镀层表面由富Al相、少量的富Fe相以及树枝晶网状分布的高Si相构成,截面是由内外两层组成,其靠近铁基体的内层为Fe-Al-Si合金层,外层为Al-Si层.进一步的研究显示,Al-Si层由富Al相、少量的富Fe相以及柱状分布的高Si相构成,高Si相主要存在于合金层与铝硅层界面以及Al-Si层中.结论 热浸镀铝硅镀层中富Al相、富Fe相、高Si相和Fe-Al-Si三元合金层的物相分别为Al、Al13Fe4、Si和Al8Fe2Si.对热浸镀铝硅镀层中高Si相的研究显示,分布于合金层与铝硅层界面处的高Si相,可以有效阻碍镀层的生长,而分布于铝硅层中的高Si相在空间中以立体网状骨架的结构形式存在,这种立体网状结构形式作为镀层的主体框架,可以有效地提高镀层的强韧性和成形性能.     

镁/钢异种金属CMT对接熔钎焊连接机理

文中用AZ61镁焊丝以及冷金属过渡焊接方法对接形式连接镁合金AZ31和镀锌钢板,在焊接过程中保持焊接速度不变,通过调节送丝速度和对钢板开不同的坡口研究不同焊接工艺参数下焊缝的表面成形、接头的力学性能和微观组织结构. 结果表明,通过调节合适的焊接参数以及坡口形式,镁-钢之间能形成焊缝成形美观、接头最大抗拉载荷达到4.02 kN的镁钢对接熔钎焊接头. 并且熔钎焊接头包括镁侧的熔焊接头和钢侧的钎焊接头,钎焊接头由两部分组成,一部分是坡口面上的镁与裸钢板之间的钎焊接头,另一部分是镀锌钢板上表面的镁-镀锌钢之间的钎焊接头. 镁-镀锌钢侧的钎焊连接主要由靠近镁侧的(α-Mg+MgZn)的共晶相,以及靠近钢侧的Fe-Al相反应层实现连接. 无镀锌层的钢和镁连接主要依靠焊丝中的微量Al元素扩散到钢表面形成Fe/Al相来实现连接.     

铜/钢爆炸复合板浸铝铸件的界面组织

采用扫描电镜技术观察和分析了爆炸复合铜／钢板浸铝铸件的铝／钢界面组织，用面扫描探明了界面组织中主要成份的分布，结合粉末样品的X射线谱确定了界面组织的相组成，用拉剪方法测得了界面的结合强度。结果表明：爆覆在钢板上的铜全部溶入铝液中，界面上出现了Fe2Al5与FeAl3两层连续的中间化合物；同时界面附近还出现了FeAl3颗粒相，这种颗粒相的形成可能和浸铝用钢板的爆炸焊接组织有关。界面的结合强度为80．5MPa。     

复合渗铝钢管焊接HAZ渗铝层相组成特征

采用光镜，电镜，Ｘ射线衍射和电子衍射等测试技术对电感应料浆法（ＧＬ）渗铝钢管焊接接头区域的力学性能和热影响区（ＨＡＺ）渗铝层的相结构特征进行了研究。试验结果表明，ＧＬ渗铝钢管焊接ＨＡＺ渗铝层主要是由α－Ｆｅ（Ａｌ）固溶体，Ｆｅ３Ａｌ相和ＦｅＡｌ构成，渗铝层中不存在含铝较高的ＦｅＡｌ２，Ｆｅ２Ａｌ５和ＦｅＡｌ３等脆性相。显改善了渗铝钢管的承受形变能力和焊接性，使焊接接头区域的组织与性能容易得到保证。     

Analysis on interfacial layer of aluminum alloy and non-coated stainless steel joint made by TIG welding-brazing

Dissimilar metals TIG welding-brazing of aluminum alloy and non-coated stainless steel was investigated. The resultant joint was characterized in order to identify the phases and the brittle intermetaUic compounds (IMCs) in the interfacial layer by optical metalloscope (OM), wanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), and the cracked joint was analyzed in order to understand the cracking mechanism of the joint. The results show that the microfusion of the stainless steel can improve the wetting and spreading of liquid aluminum base filler metal on the steel surface and the melted steel accelerates the formation of mass of brittle IMCs in the interracial layer, which causes the joint cracking badly. The whole interfacial layer is 5 - 7 μm thick and comprises approximately 5 μm-thickness reaction layer in aluminum side and about 2 μm-thickness diffusion layer in steel side. The stable Al-rich IMCs are formed in the interfaciallayer and the phases transfer from (Al + FeAl3) in aluminum side to (FeAl3+ Fe2Al5) and (α-Fe + FeAl) in steel side.     

铝合金/镀锌钢板Nd:YAG激光+MIG电弧复合热源熔-钎焊接头的组织与性能(英文)

基于铝合金和镀锌钢在熔点上的差异,以ER4043(AlSi5)为填充材料,采用大光斑Nd:YAG激光+MIG电弧复合热源焊接工艺实现两者的熔-钎焊接,研究熔钎焊接头组织和性能。铝合金/镀锌钢板熔钎焊接头分为熔焊接头和钎焊缝两部分,熔焊缝组织由α(Al)等轴晶和晶界上短棒状的Al-Si共晶组织组成,焊趾处的富锌区为α-Al-Zn固溶体和Al-Zn共晶组织。钎焊缝为Fe-Al金属间化合物层,厚度为2~4μm,金属间化合物包括FeAl2、Fe2Al5和Fe4Al13,其中FeAl2和Fe2Al5位于近钢侧的紧密层,而Fe4Al13则呈舌状或锯齿状向熔焊缝内生长。接头抗拉强度随着焊接电流和激光功率的增大呈先增大后减小的趋势,最高可达247.3 MPa。拉伸断裂位置一般位于熔焊缝的熔合区,为以韧性断裂为主的混合断裂。接头内硬度的最大值位于钎焊缝处,然后分别沿着两侧钢板和铝合金熔焊缝逐步降低。