321不锈钢焊接波纹管失效分析

应用光学显微镜、扫描电镜和能谱仪等手段对321不锈钢焊接波纹管表面腐蚀物的化学成分、焊缝区域的显微组织、腐蚀裂纹的形态特征等方面进行检验和分析。结果表明，波纹管局部电镀端内壁腐蚀导致漏气失效，即加工应力、焊接残余应力与含Cl^-或含Cl^-和溶解氧的腐蚀性介质的联合作用使波纹管局部电镀端产生了点蚀和应力腐蚀开裂；退火工艺设计的不合理和钎焊工艺控制不恰当使焊缝热影响区敏化而出现了晶间腐蚀。据此提出了降低和避免321不锈钢焊接波纹管因腐蚀而漏气的措施。     

铜管焊接弯头开裂分析

利用光学金相显微镜、扫描电子显微镜、电子能谱仪等方法对开裂铜管焊接弯头进行失效分析,发现该铜管焊接弯头久置于腐蚀性介质中,当在腐蚀坑处应力集中,便产生了开裂失效.同时,还发现该工件在弯制时易形成微裂纹.     

甲醛车间外管线裂纹泄露机理分析

通过对甲醛生产车间室外主工艺管线工作环境考察,管线弯管处的裂纹部位进行观察,并通过对裂纹处成分、组织和裂纹形貌进行分析,得出奥氏体不锈铜管线预制产生加工硬化和马氏体相变,焊接产生马氏体相变和焊接残余应力,以及管线所在外部环境造成管表面氯离子富集是造成管线裂纹的根本因素,得出了管线弯管裂纹泄露失效的原因;并提出了治理和防范管线弯管处容易产生裂纹泄露失效的具体办法。     

压缩机铜管钎焊接头裂缝原因分析

采取化学成分分析、金相检验、扫描电镜(SEM)断口分析方法对压缩机铜管钎焊接头裂缝缺陷进行研究与分析,并通过在线模拟试验方法验证分析结果。结果表明,铜管钎焊接头裂缝主要原因为接头受到不均匀的二次加热出现收缩不一致,局部加热温度过高且超过钎料熔点使钎料重新熔化,钎料再次凝固时,部分空气残留在焊缝区域伴随钎料一起冷却,最终在钎料内部形成疏松和孔洞,降低钎焊接头强度;钎焊接头母材的热膨胀系数不同,使钎料在冷却过程中形成的内应力过大,最终导致铜管钎焊接头出现裂缝。     

超超临界火电机组热交换器BFe10-1-1白铜管泄漏分析

某超超临界火电机组热交换器BFe10-1-1白铜管运行4a(年)后发生泄漏失效。通过宏观观察、化学成分分析、金相检验、断口分析、管子内壁沉积物检验等方法对白铜管的失效原因进行了分析。结果表明:白铜管内壁存在明显的沉积物,沉积物下形成氧浓差腐蚀,导致管子内壁产生点腐蚀;点腐蚀坑区域Cl~-存在对于晶界部位的铁元素产生进一步腐蚀使得富集于晶界处的铁元素不断流失而形成空位,空位的不断形成及合并导致晶间裂纹的萌生,最终导致管子发生晶间腐蚀开裂。     

某型非标准波导管钎焊接头裂纹分析

针对某型非标准波导管使用中发现90°波导弯头钎焊接头处存在裂纹的问题,运用X光检测和扫描电镜分析等手段,对裂纹产生的原因进行了分析。结果表明:在波导管加工过程中,线切割后的焊接面形成一层氧化膜,由于钎焊前清洗不彻底,在焊接时焊料无法粘结,造成钎料未钎满;另波导管在焊接时定位不准,偏向一边,造成单边间隙过小,焊料不能充分流入,使得波导管在焊接过程中焊料未能充分渗透、填满。根据故障原因,采取了相应的改进措施,使钎焊接头裂纹问题得到了解决。     

L-B型组合式制动梁产生裂纹原因的分析与建议

采用残余应力和力学性能测定、化学成分分析、断口扫描及金相检验等方法对铁路货车用L-B型组合式制动梁撑杆翼板产生裂纹的原因进行了分析。结果表明，由于焊前未预热且焊接工艺不规范，导致在焊缝处存在较大残余拉应力和不良显微组织；焊后又未采取必要措施消除上述缺陷；加上材质本身存在力学性能和化学成分不符合有关标准的要求，使该制动梁在运行中产生裂纹，最终导致失效。提出了改进措施。     

紫铜管焊接接头的断裂分析

对紫铜管焊接接头零件的断裂从成分、金相、断口等方面做了综合分析.金相分析表明,裂纹萌生于紫铜管的内外壁表面,沿晶界向壁中心扩展.金相和能谱分析证实,断口附近紫铜管基体晶界上含有大量的Cu2O第二相和一定的杂质元素铁,这些均使基体的晶界强度大大降低.断口分析表明,该铜管断口为沿晶韧性断裂特征.同时,来样铜管断裂位置均距焊接部位较近,计算表明,在高温(600～700℃)焊接过程中由于铜具有较高的导热率和热膨胀系数,因而在焊接过程中将在总接头长度范围内产生约0.5～1mm的热膨胀,从而在组织中会产生较大的热应力.综合分析认为,轧制铜管本身组织应力、焊接过程的热应力以及水压试验应力的共同作用导致晶界裂纹源的萌生、扩展和最终的沿晶韧性断裂.     

安全阀配对法兰焊口裂纹产生原因分析

某集气装置原料气放空安全阀配对法兰焊口处出现裂纹,通过宏观以及微观检验、化学成分分析、力学性能测试等方法对裂纹产生的原因进行了分析。结果表明：该裂纹为硫化物应力腐蚀开裂所致,焊接工艺不当或焊后冷却速度过快导致焊接接头区域出现硫化物应力腐蚀开裂敏感性组织是该焊口产生裂纹的主要原因。     

船体外板装配焊接裂纹分析

某船体尾部外板装配焊接后出现一条贯穿于焊缝和母材的裂纹,通过对船板原材料进行理化性能检验和裂纹断面进行宏、微观检查,对船体外板裂纹产生的原因进行了分析。结果表明:船体外板开裂主要是由于焊接顺序及焊接措施不当,导致船板强制装配拘束应力大,焊缝中存在较多焊接缺陷,从而使得裂纹在两条焊缝交接处的高应力区萌生并延伸扩展至母材区。     

紫铜焊接脆化原因分析

通过对材料的金相组织和断口的SEM观察,对压缩机贮液罐用铜导管的脆断进行了分析,认为铜管氧含量过高,钎焊时被C2H2还原是造成脆化的重要原因。     

Liquid metal induced embrittlement in fuel line braze joints

This paper documents an instance of liquid metal induced embrittlement (LMIE) that occurred during the manufacture of automobile engine fuel lines. The fuel lines were constructed of low-carbon steel fittings press fit onto 304 stainless steel tube. The joints were subsequently furnace brazed with copper braze paste. The carbon steel fittings were occasionally observed lying separately as the part exited the brazing furnace. Failure analysis using metallographic techniques, scanning electron microscopy, and energy-dispersive spectroscopy indicated that the fractures were intergranular with no observable ductility. Copper from the braze filler metal was observed on the stainless steel tube fracture surfaces and within the tube wall grain boundaries. Copper and austenitic stainless steel are a well-known LMIE couple. Subsequent investigation indicated the stress required for rapid fracture was due to impacts of the parts against one another and the brazing furnace stationary components while the braze metal was liquid.     

焊接参数对中频逆变铜管焊接质量的影响

根据压缩机的使用要求,铜管焊缝应具有较强的密封性、焊接强度和良好的物理性能。本文针对壳体与铜管中频逆变焊工艺,通过调整焊接压力、焊接时间和焊接电流3个主要参数的对比试验,确定合理的焊接参数。试验结果对实际控制铜管焊接质量具有一定的指导意义。     

Laser–arc hybrid welding of high-strength steel and aluminum alloy joints with brass filler

The laser–tungsten inert gas hybrid welding method was adopted to realize the welding process between Q460 high-strength steel and 6061 aluminum alloy. The influence of the dual heat source on the mechanical properties and microstructure of the welded joints are discussed. In addition, the effects of including a copper–zinc interlayer on the microstructure, elemental distribution, and mechanical properties of welded joints are also studied. The results show that the mechanical properties of the welded joints are influenced by the relative heat inputs of the two heat sources and the Cu-Zn interlayer. The braze welded joint fabricated without a Cu-Zn interlayer fractured at an Al-Fe intermetallic compound (IMC) layer formed at the interface, whereas the braze welded joint fabricated with a Cu-Zn interlayer fractured at an Al-Cu IMC layer formed at the interface. Comparisons show that the maximum tensile shear load of the brazed welded joint with the Cu-Zn interlayer was increased by about 20% relative to that formed without the interlayer. The formation of Al-Fe IMC layer in the deep penetration joint was inhibited by the combined effect of the dual heating sources and the Cu-Zn interlayer.     

制冷装置管道钎焊工艺

钎焊作为一种常用的焊接方法,在形状复杂和薄壁零件连接中获得广泛应用。本文针对制冷装置中管道连接的特点和要求,阐述制冷装置管道钎焊工艺的要点,包括钎焊前的检查和准备、加热焊接中的操作要领和钎焊后处理等。     

铍焊接技术研究发展概况

铍及铍合金在航空航天、电子工业和国防工业等方面应用十分广泛.结合铍的焊接性,论述了当前国内外铍的焊接技术概况,针对钎焊、熔化焊、扩散焊等焊接工艺,介绍了一些比较成功的铍的焊接工艺以及部分连接工艺,同时分析了铍焊接中存在的缺陷问题.     

Evaluation of braze materials used for automotive liquid hydrogen tanks with special respect to hydrogen embrittlement and low temperature toughness

Copper (CU 104 and CW021A), Nickel (NI 102 and MBF51) and Silver (AG102) braze joints with stainless steel 1.4401/1.4404 were investigated with respect to hydrogen embrittlement and cryogenic toughness. CW021A and MBF51 with different braze thicknesses and temperatures were Charpy V tested at 20 °C and ‐196 °C. Neither the seam thickness nor the test temperature had a significant influence on the Charpy V toughness. All toughness values were below 15 J/cm². The reason is the low thickness of the braze seam and therefore the low volume of deformable material. CU 104, CW021A, NI 102, MBF51 and AG102 braze joints were tensile tested in hydrogen of different pressures and temperatures. Neither of the soldering showed any kind of hydrogen embrittlement.     

AlN陶瓷的薄膜金属化及其与金属的焊接研究

针对AlN陶瓷在微波管中的应用特点 ,采用磁控溅射镀膜方法对AlN陶瓷进行表面金属化 ,并与无氧铜焊接 ,测试焊接体的抗拉强度并对陶瓷 金属接合界面进行了微观分析。     

空调器中铜管焊接分析

对空调器中的铜管焊接方法、影响因素及常见的问题进行分析,阐述出现问题的原因,提出预防措施。     

Applying of ultrasonic waves on brazing of alumina to copper using Zn-Al filler alloy

Ultrasonic waves were applied during brazing of alumina to copper, The intensity of ultrasonic wave was 1 kW and 18 kHz and the aim of this work was to study the effect of the ultrasonic wave and brazing temperature on the properties of the braze joint between alumina and copper using Zn-Al alloys as filler metal.First the alumina was metallized by applying on ultrasonic wave in a Zn-Al braze bath. Then the metallized alumina was brazed with copper using the same filler alloy. The joining mechanism was investigated by measuring the joining strength and analyzing the microstructure at the interface of the joint. The ultrasonic waves improved the wetting in the molten Zn-Al bath by accelerating the removal of bubbles from the interface between alumina and the filler, and this was reflect in improved joint strength.