压力容器用铝合金5083-O厚板搅拌摩擦焊研究

采用搅拌摩擦焊对5083-O厚板铝制压力容器进行了焊接,焊后用万能试验机对不同参数的接头进行了拉伸试验,并使用光学显微镜对焊接接头组织和表面形貌进行了分析。结果表明:在焊接速度50 mm/min、旋转速度1800 r/min的情况下,获得的接头拉伸性能最高可达到296 MPa;同时焊缝表面平整规则,界面结合良好。     

碳纤维增强聚苯硫醚复合材料感应焊接研究

以碳纤维/聚苯硫醚(CF/PPS)层合板为研究对象,采用DOE方法优化设计感应焊接实验方案,研究焊接接头性能,并对其截面和断口形貌进行观察,揭示焊接工艺参数对焊接接头性能的影响机制。结果表明,通过DOE方法获得最佳焊接工艺参数(功率2.0kW、压力1.5MPa、时间3.0min),焊接接头最大单搭接剪切强度为13.87MPa,与实验验证结果(13.25MPa)相近;接头剪切强度随着焊接工艺参数值的增加,均呈现先增大后减小的变化趋势;在最佳焊接工艺参数下,焊接接头结合紧密,失效形式为不锈钢网的撕裂与纤维的断裂拔出,呈现出高剪切强度;而在过低或过高焊接工艺参数下,界面脱黏为主要失效形式,剪切强度较低。     

42CrMo/GH4169异种金属连续驱动摩擦焊焊接接头组织性能分析

采用连续驱动摩擦焊的焊接方法对42Cr Mo和GH4169进行异种材料焊接。利用光学显微镜、扫描电镜等仪器分析了连续驱动摩擦焊焊接接头的外观特征、显微组织和断口形貌等,并分别利用维氏显微硬度仪和拉伸试验机检测了接头区域硬度和接头强度。结果表明,使用连续驱动摩擦焊对42Cr Mo和GH4169进行焊接时,接头缺陷较少,接头及热力影响区域(HFZ)力学性能较好,软化区软化程度较小,接头成型质量较好。     

低体积分数SiCp/Al复合材料封装盒体搅拌摩擦焊研究

碳化硅颗粒增强铝基复合材料具有优异的性能,在许多领域都备受青睐,然而焊接性较差,成为制约其广泛应用的瓶颈难题.本文采用搅拌摩擦焊的方法,实现了低体积分数SiCp/Al复合材料封装盒体的连接.试验中采用圆锥形WC-Co合金搅拌头,搅拌头轴肩直径为10 mm,锥头直径3 mm,锥尾直径5 mm,搅拌针高度2.5 mm,采用下压力控制方式,焊接工艺参数为:下压力控制在2 kN,搅拌头倾角为3°,搅拌头转速为1500 RPM,焊接速度保持在120 mm/min,下压深度为2.55 mm,能够获得表面及内部质量良好的焊接接头.经过搅拌摩擦焊后,搅拌区的碳化硅颗粒尺寸更加细小,分布也更加均匀,搅拌区中没有出现孔洞、沟槽等搅拌摩擦焊常见缺陷.热机影响区内部分布着大量严重变形的结构,这主要是由于母材组织被拉长后伴随着塑性流动而产生的较大变形.母材区的平均硬度值最高,为61.9 HV3,搅拌区的平均硬度为58.3 HV3,热机影响区的平均硬度最低,为55.4 HV3.     

树脂基复合材料界面结合的研究I:界面分析及界面剪切强度的研究方法

本文分析了树脂基复合材料受力状况下对界面结合的要求 ,着重介绍了微量冲击和临界纤维断裂长度分析两种检测树脂基复合材料界面剪切强度的方法及其研究成果。通过对单丝纤维断点周围基体树脂形态的分析 ,提出了一种判断优化界面的方法。     

树脂基复合材料界面结合的研究Ⅱ:界面优化及界面横晶的研究

分析了树脂基复合材料受力状况下对界面结合的要求,着重介绍了微量冲击和临界纤维断裂长度分析两种检测树脂基复合材料界面剪切强度的方法及其研究成果.通过对单丝纤维断点周围基体树脂形态的分析,提出了一种判断优化界面的方法.     

树脂基复合材料界面结合的研究Ⅰ:界面分析及界面剪切强度的研究方法

本文分析了树脂基复合材料受力状况下对界面结合的要求,着重介绍了微量冲击和临界纤维断裂长度分析两种检测树脂基复合材料界面剪切强度的方法及其研究成果.通过对单丝纤维断点周围基体树脂形态的分析,提出了一种判断优化界面的方法.     

CF/纳米SiO_2改性树脂复合材料界面性能研究

本文以纳米SiO2改性树脂作为树脂基体,以连续碳纤维作为增强体制备复合材料,研究了纳米SiO2掺入树脂中百分含量对树脂基体与增强体之间的界面性能的影响。通过对树脂基体与增强体纤维浸润性、微脱粘、层间剪切强度和扫描电子显微镜,对复合材料界面性能测试和表征。结果表明,随着纳米SiO2含量的增加,常温下,基体树脂和增强体纤维浸润性能下降,单丝纤维与树脂微球的界面剪切强度和复合材料单向板层间剪切强度在某一含量范围均有所提高。     

竹片/环氧乙烯基酯树脂复合材料的界面性能研究

采用不同浓度的碱与不同浓度的硅烷偶联剂对竹片进行表面改性,研究了表面改性对竹片抗拉强度及其复合材料制品界面层间剪切强度的影响。实验结果表明:适当浓度的碱处理改性方法对竹片拉伸强度和竹复合材料界面剪切强度的提高要明显优于KH550改性方法,双重改性对竹片的抗拉强度具有较好的改善效果;通过扫描电镜分析冲击断面破坏方式发现,竹片/环氧乙烯基酯树脂复合材料界面损伤模式主要表现为竹片中竹纤维抽拔断裂、基体断裂、纤维/基体界面脱粘以及剪切分层,界面性能有所改善。     

热固性树脂基复合材料结构电阻焊接研究

采用碳纤维增强环氧树脂复合材料层压板与热塑性粘接剂共固化工艺,制备层压板焊接面覆有粘接剂的复合材料结构试件,利用粘接剂作为焊接介质对热固性环氧树脂基碳纤维复合材料结构试件进行电阻焊接。粘接剂与环氧树脂基体界面形成了半互穿网络聚合物(S-IPN)结构,有利于提升粘接剂与环氧树脂基体界面粘接性能,提高接头强度。对焊接试件的接头力学性能表征表明:采用AX8900粘接剂作为焊接介质的试件接头强度最高;单搭接剪切强度(LSS)可以达到7.35MP;编织碳纤维和金属网作为加热电阻可以使接头强度较单向碳纤维加热电阻分别提高60%和73%;[0°/90°]编织碳纤维加热电阻焊接的AX8900试件的平均层间断裂韧性可达1880J/m2。根据[0°/90°]编织碳纤维加热电阻焊接AX8900试件的LSS建立了基于焊接时间和功率密度的焊接工艺窗口。     

Investigations on Mechanical and Metallurgical Properties of Friction Welding of AlB<Subscript>2</Subscript> Reinforced Aluminum Matrix Composites

Friction stir welding (FSW) of AlB₂ reinforced aluminum matrix composites was conducted by varying two process parameters namely rotational speed of the tool and travelling speed. Six welds were made on the metals to determine the optimum level of process parameters for welding aluminum matrix composites. Microstructures evaluation conducted by optical microscopy (OM) and scanning electron microscopy shows the boron particle agglomerations at the interface of joints form larger grain structures in the stir zone (SZ). Mechanical properties were investigated using a tensile strength test and microhardness measurements. The joints made with rotational speed of 1000 rpm and travelling speed of 10 mm/min exhibit the highest strength of 152.7 MPa in the weld zone. The friction coefficient, wear behavior and scratch morphology of the friction stir welded AMCs were studied. The hardness and wear properties improved in the base metal region in comparison to the welded region.     

Studies on Fractures of Friction Stir Welded Al Matrix SiC-B<Subscript>4</Subscript>C Reinforced Metal Composites

Studies pertaining to joining of Al alloy metal matrix composites reinforced with B₄C and SiC by solid state friction stir welding (FSW) are presented in this paper. FSW tool dimensions are designed and fabricated to suit the weld sample dimensions and subsequently, the implications of the tool pin profile on the weldability is investigated. Through experimental recordings, the heat generated during the friction stir joining process of composites is estimated by developing relative equations. Maintaining the tool traverse speed constant, the rate of rotation and its effects on the tensile strength at the joints are investigated which reveals reduced ductility. The study emphasizes that when the speed is maintained between 100–400 mm/min, the tensile strength is at its optimal maximum while speeds higher or lower than the optimal range indicate detrimental effects on the tensile strength. This is followed by fracture studies on samples welding with varying traverse speed and rate of welding. Traverse speed appears to govern the fracture modes while brittle fracture is predominantly noticed indicating the importance of feeding optimal heat input during joining.     

Lap joint formed by friction stir spot welding between SiC and magnesium alloy containing aluminum

A lap joint between plates of SiC and AZX612-magnesium alloy containing aluminum was formed by friction stir spot welding using a drilling machine. The joint interface was analyzed by scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. Aluminum from the AZX612-magnesium alloy segregated along the joint interface suggesting that SiC and AZX612-magnesium alloy could be strongly joined by friction stir spot welding due to the formation of aluminum compounds. SiC and A1050-aluminum alloy plates were joined by friction stir spot welding and a tensile-shear test was performed. At 245 N, the lap joint fractured in the SiC matrix rather than the joint interface. These results confirmed that SiC and A1050-aluminum can be strongly joined due to the formation of aluminum compounds.     

Microstructure,Hardness and Tensile Properties of Friction Stir Welded Aluminum Matrix Composite Reinforced with SiC and Fly Ash

Silicon - In the present work, aluminum alloy 6061/SiC/fly ash aluminum matrix composites were welded successfully using friction stir welding process. Microstructure of weld joints was examined...     

Microstructures and mechanical properties of thin 304 stainless steel sheets by friction stir welding

Friction stir welding (FSW) was performed on 304 stainless steel sheets. The welding speed was varied from 30 to 70 mm/min. Because the FSW of thin plates is sensitive to heat input. The surface of the welds is smooth and without any macroscopic cracks and cavities only when the rotation speed is 50 mm/min. The stir zone had equiaxed grains with austentic structure due to dynamic recrystallization. There was not any evidence for the presence of sigma phases being found in this study. Meanwhile, there was a weak region in the advancing side because of the flow of plastic metals. However, compared with the base material, mechanical properties of the joint are maintained in a comparatively high level.     

Establishing Mathematical Relationships to Study Tensile Behavior of Friction Stir Welded AA5086-H32 Aluminium Alloy Joints

Silicon - In the present work, 5 mm thick rolled plates of AA5086-H32 alloy were friction stir butt welded, varying the six input process parameters, namely rotational speed, welding speed, tool...     

Effect of welding parameters on the heat affected zone and the mechanical properties of friction stir welded poly(ethylene-terephthalate-glycol)

The bond strength and the heat affected zone (HAZ) of friction stir welded seams made of poly(ethylene-terephthalate-glycol) are analyzed in the article. The seams were prepared with various settings (rotation speed and feeding rate) and with various welding tools. Using the welding parameters (rotation speed, the feed rate, and the tool diameter) a K-factor characterizing the welding process was defined. The novel K factor is related to the welding heat input, which is in direct correlation with both the range of the HAZ and the mechanical properties of the seam. The HAZ formed was analyzed by stress optical method, the mechanical properties by flexural test. It has been demonstrated that the efficiency factor of the welded joint is closely related to the width of the HAZ and it depends on the welding parameters and the tools. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Comparative potential of alternative wood welding systems,ultrasonic and microfriction stir welding

Two alternative welding systems were evaluated for wood welding. Ultrasonic welding produces joints of good strength but it appears to be applicable only to thin wood pieces. It does not appear that further possible process improvement could bring the joint strength to a structural level. Microfriction stir welding does show potential for welding continuously wooden plates without any limitation on length of wood pieces. The strength of the weld obtained was low due to the limited depth of the weldline. Optimisation of parameters is necessary. A drawback at present appears to be the limited thickness of the wooden pieces that can be welded. X-ray micro densitometry, scanning electron microscopy and optical microscopy showed that the main difference compared to the other techniques is that in the microfriction stir weld, there is a veritable welded line of molten material. This molten material comes from the wood in contact with the rotating steel cylinder, which has flowed down in the micro gap between the two pieces of timber where it has bonded by solidifying.     

聚丙烯塑料板搅拌摩擦焊接头缺陷分析

搅拌摩擦焊具有高效、节能、无污染等优点,既能焊接铝合金等低熔点材料,也能焊接聚丙烯塑料板材。各种工艺参数合理匹配时,焊缝美观,质量良好。但是,工艺参数选择不当时,焊缝会存在明显缺陷。本文分析了用搅拌摩擦焊焊接聚丙烯塑料板时所出现的飞边、孔洞等缺陷。