Improving pulsed laser weldability of duplex stainless steel to 5456 aluminum alloy via friction stir process reinforcing of aluminum by BNi-2 brazing alloy

Effects of laser pulse distance and reinforcing of 5456 aluminum alloy were investigated on laser weldability of Al alloy to duplex stainless steel (DSS) plates. The aluminum alloy plate was reinforced by nickel-base BNi-2 brazing powder via friction stir processing. The DSS plates were laser welded to the Al5456/BNi-2 composite and also to the Al5456 alloy plates. The welding zones were studied by scanning electron microscopy, X-ray diffractometry, micro-hardness and shear tests. The weld interface layer became thinner from 23 to 5 μm, as the laser pulse distance was increased from 0.2 to 0.5 mm. Reinforcing of the Al alloy modified the phases at interface layer from Al-Fe intermetallic compounds (IMCs) in the DSS/Al alloy weld, to Al-Ni-Fe IMCs in the DSS/Al composite one, since more nickel was injected in the weld pool by BNi-2 reinforcements. This led to a remarkable reduction in crack tendency of the welds and decreased the hardness of the interface layer from ~950 HV to ~600 HV. Shear strengths of the DSS/Al composite welds were significantly increased by ~150%, from 46 to 114 MPa, in comparison to the DSS/Al alloy ones.

Fabrication of in-situ synthesized ceramic reinforced Ni-based alloy composite coatings by reactive braze coating processing

In-situ synthesized ceramic such as TiC,Cr7C3 and Cr5B3 reinforced Ni-based alloy composite coating was fabricated on the surface of mild steel substrate by reactive braze coating processing with colloidal graphite,Cr,Ni,ferro-boron,Si and titanium powders as the raw materials at low temperature of 1000℃,and a new kind of coating materials was developed.By means of SEM,EDS,XRD and surface hardness tester,the microstructures,phases,hardness and wear-resistance of the coating were analyzed,respectively.The results revealed that the coating was mainly composed of the ceramic in-situ synthesized reinforcement phases of TiC,Cr7C3 and Cr5B3 and the binder phases in-situ synthesized of Ni31Si12 and(Ni,Fe)solid solution;The ceramic reinforcement phases of TiC,Cr7C3 and Cr5B3 were randomly distributed in the binder phases of Ni31Si12 and(Ni,Fe)solid solution;The coating had about 15vol%pores and can possibly be applied as a self-lubrication coating;The coating and the substrate were integrated together by metallurgical bonding;The coating had a hardness up to 91-94HR15N.

Influence of filler metal and processing on brazed joints of TiAl alloy and 42CrMo

The filler metals of AgAlTi and AgAlTiCo were selected for the vacuum brazing of TiAl alloy and 42CrMo under different processing parameters. The results show that for both filler metals, the highest tensile strength of joint can be achieved at 950℃, 15min, and with the addition of Co the joint strength becomes higher. By the comparison of the microstructure of joints, the joint interface is the main factor that influences the joint strength.

The Integration of Vacuum Brazing into Heat Treatment - A Progressive Combined Process

The continuous constructive challenge to improve the functionality and efficiency of components always results in higher demands on production engineering, against the background of the generally increasing cost pressure. In many cases, you will just succeed in producing competitive and innovative products by combining and coupling of different procedures to an independent (hybrid) technology. The use of hybrid procedures for metal joining and heat treatment of metallic materials finds more and more industrial fields of application. Modern vacuum lines with integrated pressurized gas quenching are considered high-performance and flexible means of production for brazing and heat treatment tasks as well in the turbine industry as in the mould making and tool manufacturing industry. In doing so, the heat treatment is coupled with the brazing cycle in a combined process so that the brazing temperatures and soak times are adapted to the necessary temperatures and times for solution heat treatment and austeniting. This user-oriented article describes on the one hand examples of brazing of turbine components, but above all the practical experience from the plastics processing industry, where the requirement for a high-efficient cooling of injection moulding dies gains more and more importance. The combined procedure "Vacuum Brazing and Hardening" offers plenty of possibilities to produce mould inserts with an efficient tempering system in an economic way.

A brief review of brazing diamond in cutting tools

Diamond has high hardness and good wear resistance.It is widely used in cutting tools and workpieces.Brazing is an effective method to realize high quality cemented carbide joints in various materials connection technologies.This paper analyzes the research status of diamond brazing in detail.The materials used as brazing filler in diamond brazing are reviewed.Copper base filler and nickel base filler are the most commonly used brazing filler in diamond brazing.The advantages and disadvantages of diamond grinding tools under different production methods are analyzed.In addition,a series of new brazing alloys such as amorphous Ni based brazing filler metals are analyzed.Finally,the development trend of diamond brazing is pointed out.

Canny edge detector and its application to analyze the brazed joint interfaces

Image processing is widely used as a method for visnal inspection in industry. Analyzing the microstructure image of a brazed joint is a very important part of the quality control in products related to brazing aUoys. Edge detection techniques are introduced to analyze the bonding strength of the brazing alloys in this paper. Gaussian filter is used for image smoothing. The sharp edge map produced by the Canny edge detector is added to the smoothed noisy image to generate the edge image, which can show the brazing elements clearly. Using the Canny edge detector as a tool to analyze the bonding strength of brazed joint, the experiment results are robust with a very high level. Therefore, the Canny edge detector can be reliably used to analyze the brazed joint interfaces.

Comparison between the electrical resistance and the shear strength of brazed cemented carbides

Brazing is a suitable technology to join different materials such as cemented carbides and steel. Even though this technology has been investigated for many years, insufficient joints can occur easily, as the brazing process is very sensitive concerning the handling parameters. Defects such as voids and cracks are hard to detect by commonly used visual inspection methods. Other nondestructive methods such as radiography or ultrasonic testing are usually not economical for the examination of these joints. Studies proved that the electrical resistance has the potential to serve as an effective alternative for the evaluation of brazed joints. In this study, the authors have compared the electrical resistance and the shear strength. For this, cemented carbides were brazed to steel by means of induction heating at an ambient atmosphere. A silver-based filler metal （ BrazeTec 4900 / Ag 449 ） and a flux （ BrazeTec spezial h / FH12） were selected to enable the brazing process. The brazing time and the temperature were varied in order to produce different joint qualities. After brazing, the resistance was measured on each joint with the 4-point probe method to facilitate a high accuracy. The results underline the possibility to use electrical resistance measurements as an effective tool for a quality control of brazed joints.

A study on reactive braze coating of (TiC+Cr_3C_2)/Fe composite coatings

A new hardfacing process, reactive braze coating process (RBCC) was studied, and (TiC+Cr_3C_2)/Fe composite coatings were prepared by RBCC using carbon, Cr_3C_2, iron, ferrochromium and titanium powder as the raw materials in vacuum braze furnace. The results show that TiC is in-situ synthesized in the coatings. The methods of introducing Cr_3C_2 have great effects on the distribution of TiC. Adding Cr_3C_2 directly to the raw materials for coatings, fine TiC particles aggregate into discoids parallel to the coating surface, whereas, in-situ synthesizing Cr_3C_2 in coatings, the aggregations of TiC are lumpish. During braze coating, Cr_3C_2 particles directly added dissolve and precipitate to become needle-shaped. The coatings have an even and smooth surface and are combined with their mild steel substrates by a metallurgical bonding.

热流道板真空钎焊有限元模拟与分析

采用BNi-2镍基钎料对热流道板进行真空钎焊,须根据钎焊件设定加热工艺曲线。加热工艺曲线的设定是钎焊过程最重要的环节之一,决定着钎焊的质量和效率。该文结合真空加热的特点及钎焊要求,运用Ansys有限元软件数值模拟的方法,对壁厚、体积较大的多层热流道板真空钎焊进行仿真分析,通过对比不同工艺方案及不同钎焊件的模拟结果,探究真空钎焊过程升温规律,从而调整各阶段的相关参数及制定合理的加热工艺曲线,避免了现场反复调试参数造成的资源浪费,节约了时间和成本,提高了效率。此外,通过在实际钎焊试验过程中布置热电偶对钎焊件测量温度,并与数值模拟结果对比,两者基本吻合,验证了有限元分析的准确性,能为之后其他零部件的真空钎焊提供参考。

纯铝导体电阻钎焊工艺与接头性能

【目的】结合电机纯铝导体绕组用材质和接头结构型式,以及钎焊纯铝的固有特点,解决在大气中实现纯铝导体绕组电阻钎焊的技术难点。【方法】以Zn-Al合金为金属皮、氟氯酸铯钎剂为药芯,与钎料制造厂家共同研制了药芯焊片。以药芯焊片为预置钎焊填充材料,药芯焊条为手工辅助钎焊填充材料,电阻钎焊为钎焊接头连接方法,进行钎焊试验。结合电机绕组用纯铝导体线规和产品结构特点,设计了纯铝导体的钎焊搭接接头,钎焊后进行了目视检测、宏观金相、维氏硬度、面钎着率、拉伸性能、直流电阻和通电温升等检测。【结果】钎焊接头目视检测结果符合ISO 18279 B级要求,接头宏观金相线钎着率和接头搭接区面钎着率检测结果符合ISO 18279 B级大于等于80%的要求,接头钎缝的维氏硬度平均值为57.8 HV0.1,接头抗拉强度平均值60.59 MPa略低于母材抗拉强度平均值63.08 MPa,接头直流电阻平均值353.64μΩ略低于母材直流电阻平均值354.93μΩ,接头通电温升平均值117.2℃略低于母材通电温升平均值117.5℃。【结论】采用0.3 mm Zn-Al药芯焊片作为预置钎焊填充材料、同材质φ2.0 mm药芯焊条作为外围辅助填充材料,可实现大气中电机绕组用纯铝导体的电阻钎焊,钎焊接头的综合性能可满足设计和工艺要求。

层状铝合金复合板钎焊工艺的研究

采取简便改进措施,探索4343/3003层状铝合金复合板在普通箱式炉中的钎焊工艺。结果表明:在普通箱式炉中,用预热的钢块使试样快速升温,同时将热电偶探头与试样表面直接接触进行测温,用木炭覆盖试样表面防止氧化,在这些改进措施实施后,可以获得质量良好的钎焊接头。讨论了钎焊温度、保温时间及载荷压力对钎缝宏观形貌和微观组织的影响,得出结论:在普通箱式炉中,均匀施加1.5 N载荷,在610℃下保温8 min或620℃下保温6 min, 4343/3003层状铝合金复合板钎焊接头质量良好。

基于Nocolok法的铝合金电子机箱钎焊工艺研究

现有的手工TIG焊接工艺不满足产品设计对精度的要求,因此开展了铝合金电子机箱钎焊工艺研究,分析了真空钎焊工艺的局限性和Nocolok法钎焊工艺的优势。进一步研究了Nocolok法钎焊的工艺参数、焊接头间隙与钎料用量,并重点针对机箱焊接效率和质量进行了设计优化和工艺改进,提出了机箱高效装夹及高精度控制措施。焊后机箱尺寸精度和形位公差均≤0.1 mm,满足了横插系列电子机箱的高精度装配需求,实现了提高批生产效率和质量稳定性的研究目标。

钎焊工艺对双层焊管材料时效性能的影响

使用退火模拟器对双层焊管用钢带进行热处理,模拟其在不同制管速度、钎焊温度下的钎焊过程。使用拉伸试验机检测不同钎焊温度及不同制管速度下钢带的屈服点延伸率和时效指数,以研究钎焊温度和制管速度对双层焊管材料时效性能的影响。结果表明,钎焊温度越高,材料的屈服点延伸率越小,时效指数也越小,制管的抗时效性越好。随着制管速度的提高,钎焊后钢带的屈服点延伸率和时效指数均呈增大趋势,抗时效性变差。这是由于制管生产速度增大,冷却段时间变短,渗碳体析出量减小造成的。钎焊前钢带时效指数为10.6 MPa,模拟钎焊后钢带的时效指数为76.8~104.9 MPa,其抗时效性明显变差。

燃气轮机扇形弧段蜂窝修理钎焊工艺研究

针对某型进口燃气轮机热端部件蜂窝封严修理开发,本文介绍了传统工艺流程修理扇形弧段蜂窝封严组件遇到的技术壁垒,通过改进衬板定位方式、创新焊料预埋方案、设计制作专用钎焊夹具、优化真空钎焊工艺参数等措施,对扇形弧段蜂窝钎焊质量进行了检测、分析,总结出一套可靠性高、钎焊质量好的标准工艺,并在实际生产中得到了广泛应用。

汽车贯穿式尾灯高度影响因素分析

汽车贯穿式尾灯设计已成为汽车主流设计之一,尾灯高度的大小直接影响车灯造型、尾灯支架结构及尾灯支架的连接工艺,进而影响可制造性及制造成本。文章在介绍汽车贯穿式尾灯的基础上,分析了影响贯穿式尾灯高度的相关因素,讨论了钣金造型设计、尾灯发光区域设计、尾门钣金结构设计、尾门钣金连接工艺等方面对贯穿式尾灯高度的影响,并分析其对整车成本的影响情况,为汽车贯穿式尾灯造型设计提供参考。

铝及铝合金钎焊用硬钎料的研究现状与展望

铝及铝合金以其优良的特性,在当代工业材料中占有越来越重要的地位。钎焊作为一种可靠连接铝及铝合金结构件的连接方法而被广泛应用。铝及铝合金钎焊用硬钎料的开发一直是国内外学者争相研究的热点,然而,钎料合金熔化温度高、加工成形性差、钎焊接头强度低等因素严重制约着钎料合金的开发应用,实现商业化的钎料甚少。添加合金元素能够降低钎料熔化温度,改善钎料显微组织和性能,这对铝钎焊用硬钎料的发展是一个行之有效的方法。结合国内外对铝及铝合金钎焊用硬钎料的最新研究成果,全面阐述合金元素的添加对钎料熔化温度、加工成形性及钎焊接头组织性能的影响,指明铝及其合金钎焊用硬钎料目前研究中存在的问题及今后的研究方向。

镍基合金钎料高频感应钎焊金刚石试验研究

选用Ni-Cr合金钎料,采用高频感应加热的方法实现了金刚石与钎料间的连接。扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)分析结果表明:钎焊过程中钎料中的活性元素Cr向金刚石表面扩散富集,生成了层片状碳化物Cr3C2。研究了金刚石感应钎焊工艺参数对钎焊质量的影响,并通过石材磨削试验确定了优化的感应钎焊工艺。

镍基钎料钎焊不锈钢的钎缝组织及工艺的研究

研究了常用镍基钎料BNi-2钎焊1Cr18Ni9Ti不锈钢的钎缝组织特征和相组成以及采用扩散热处理和加压钎焊工艺对钎缝组织的影响,钎缝宽度对接头性能的影响。研究结果表明,采用合适的扩散热处理和加压钎焊工艺可以有效的消除钎缝组织中的脆性化合物相,合适的钎缝宽度可以提高钎焊接头的物理性能。

大粒度镍基合金焊料真空钎焊金刚石工艺

为解决金刚石钎焊工艺所用粉末状合金焊料用量难以控制、焊料层均匀性较差的问题,提出大粒度合金焊料真空钎焊金刚石的工艺构想并建立了几何模型,得出金刚石最优钎焊效果的大粒度合金焊料与金刚石粒度关系方程组,并求得基于合金焊料润湿角的实际解.根据测定的镍基合金焊料润湿角得出50目大粒度合金焊料匹配的金刚石粒度为60目.进行了金刚石真空钎焊试验与重负载磨削试验.结果表明,大粒度镍基合金焊料熔化完全,流淌性好,对金刚石具有良好的包埋、爬升效果;金刚石出露60%~70%,表面清洁无杂质.重负载磨削后金刚石出现刃口磨损、局部破碎、磨平三个正常磨损状态,证明了新工艺的可行性.

金刚石磨粒用钎料的研制及钎焊工艺

通过分析钎料元素对金刚石作用的原理,研制出了AgCuNi、AgCuCr和AgCuTi3种适合不同钎焊条件的焊接金刚石磨粒的钎料,并进行了钎焊工艺研究。试验结果表明,采用二次钎焊和两级加热工艺,用所研制的钎料并在自制的钎焊装置中,能够实现小规模加工钎焊单晶金刚石磨料片。