Corrosion Evolution in Al/Steel Dissimilar Joints

2020 ◽  
Author(s):  
Weiling Wen ◽  
Tian Liu ◽  
Mihaela Banu ◽  
Joseph Simmer ◽  
Blair Carlson ◽  
...  
Keyword(s):  
Automotive Industry ◽  
Emission Reduction ◽  
Spot Welding ◽  
Mechanical Performance ◽  
Dissimilar Joints ◽  
Corrosion Initiation ◽  
Cyclic Corrosion ◽  
Initiation And Propagation ◽  
Corrosion Mechanisms ◽  
Steel Joints

Abstract Al/steel joints are increasingly used in the automotive industry to meet the requirement of energy saving and emission reduction. Among various joining technologies, self-pierce riveting (SPR) and resistance spot welding (RSW) are two promising technologies to fabricate dissimilar joints with stable and high mechanical performance. However, corrosion will occur in these joints inevitably due to different electrochemical properties, which can degrade the surface quality and the mechanical performance, including strength, ductility, etc. In this paper, 1.2 mm AA6022 and 2.0mm HDG HSLA340 are joined by SPR and RSW. After the fabrication of these Al/steel joints, cyclic corrosion tests are performed, which lasts 26 cycles and 48 cycles. By comparing the microstructure of the joints with and without corrosion, different corrosion mechanisms in SPR and RSW are revealed, including the corrosion initiation and propagation.

Resistance spot welding of additively manufactured maraging steels Part II: Failure behavior

2021 ◽  
pp. 1-31
Author(s):  
Cheng Luo ◽  
Yansong Zhang ◽  
Michael Oelscher ◽  
Yandong Shi ◽  
Niels Pasligh ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Fracture Mode ◽  
Automotive Industry ◽  
Material Properties ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Melting Process ◽  
Spot Welds ◽  
Laser Melting ◽  
Maraging Steels

Abstract Application of maraging steels via selective laser melting process in the automotive industry was unavoidably involved in the resistance spot welding with conventional steels. Due to the rapid cooling rate of welding process, selective laser melted maraging steels with unique chemical components and stack microstructure could induced the different microstructural evolution, resulting in the complicated fracture behavior in the spot welds. This paper developed a FEA model to predict the fracture mode of spot welds of DP600 to maraging steel and the effect of test conditions and printing orientations were studied. A method was proposed to calculate the material properties of fusion zone by introducing the combined effect of melting DP600 and maraging steels via selective laser melting, resulting in the accurate prediction of fracture mode and strength of spot welds. An interlayer with lower strength was found around the fusion zone and the fracture path propagated in the region, resulting in the partial interfacial failure of spot welds. Meanwhile, the printing orientation had no significant effect on the fracture mode and strength of spot welds, but the different material properties of maraging steels could affect the fracture displacement of spot welds. These findings could pave a way to guide the application of maraging steels via selective laser melting process in multiple industries, especially in the automotive industry.

Suppressing Cracking in Resistance Welding AA5754 by Mechanical Means

2000 ◽  
Author(s):  
Hongyan Zhang ◽  
Jacek Senkara ◽  
Xin Wu
Keyword(s):  
Temperature Field ◽  
Crack Initiation ◽  
Spot Welding ◽  
Mechanical Analysis ◽  
Crack Initiation And Propagation ◽  
State Of Stress ◽  
Initiation And Propagation ◽  
Thermal Mechanical Analysis ◽  
The Impact ◽  
Analytical Approaches

Abstract In this paper mechanical aspects of cracking during single- and multi-spot welding of AA5754 was investigated by both experimental and analytical approaches. The impact of mechanical loading on crack initiation and propagation was studied with the consideration of various process parameters including the loading imposed by electrodes, the formation of liquid nugget, and constraining factors during and after welding. Tensile properties of AA5754 and their dependence on the temperature were tested at room and up to solidus temperatures, in order to provide a reference of cracking stress. Thermal-mechanical analysis was conducted based on the temperature field around the nugget and the state of stress encountered during welding. This analysis revealed that tensile stress might build up in the vicinity of the nugget during cooling, thus explained the experimental observation. General guidelines for suppressing cracking were proposed, i.e. to provide sufficient constraint around the weld spot during and after welding.

Fundamental Aspects, Mechanical Behaviour and Mathematical Understanding of Friction Spot Stir Welds: A Review

2021 ◽  
Vol 39 (11) ◽  
Author(s):  
Arash Fattahi ◽  
E.E. Supeni ◽  
M.K.A. Ariffïn ◽  
M.R. Ishak ◽  
Sahar Zolfaghari ◽  
...  
Keyword(s):  
Spot Welding ◽  
Mechanical Performance ◽  
Processing Parameters ◽  
Friction Stir Spot Welding ◽  
Mathematical Understanding ◽  
Environmental Conservation ◽  
Service Industries ◽  
Effective Control ◽  
Friction Stir ◽  
Welding Processes

The energy-saving and environmental conservation are increasingly important issues in manufacturing and service industries worldwide that have received considerable attention in recent years. Most importantly, this process eliminates the grain solidification errors generated by the standard fusion process. Thus, in this papers types and methods of stir welding will be explained and discussed accordingly .   Friction stir spot welding is a tunable method as it allows an effective control and amendment of processing parameters using refill and powder-assisted schemes that can solve the problem of the keyhole and mechanical weaknesses in the joining of light metals processed by conventional Friction stir spot welding. This comprehensive review mainly focuses on the fundamental aspects of Friction stir spot welding processes and their impacts on the microstructural features and mechanical performance and mathematical understanding of various similar and dissimilar systems. To conclude, the challenges in further modification of Friction stir spot welding and future outlooks in different engineering applications are presented.

Application of Laser Remote Welding to an Aluminum Automotive Part

2010 ◽  
Vol 654-656 ◽  
pp. 966-969
Author(s):  
Cheol Hee Kim ◽  
Won Ho Choi ◽  
Ki Young Park
Keyword(s):  
Laser Welding ◽  
Automotive Industry ◽  
Spot Welding ◽  
Thin Disk ◽  
Al Alloys ◽  
Thermal Distortion ◽  
Focal Distance ◽  
High Brightness ◽  
Automotive Part ◽  
Remote Welding

Aluminum alloys are extensively used in the automotive industry in response to increasing requirements for weight reduction in car body architecture. Laser welding of Al alloys has many advantages such as low heat input, narrow heat affected zone, minimal thermal distortion and flexibility. Recently, the development of high brightness lasers - thin disk lasers and fiber lasers enable long focal distance welding so that laser remote welding with scanning mirrors can be used in laser welding of Al alloys. In this study, laser remote welding was implemented to a heat shield part of an automobile by utilizing a 4kW disk laser and a 2-axis scanner. By replacing conventional resistance spot welding, the weld flange length could be reduced from 15mm to 8mm and a cycle time for each welding point could also be reduced from 3.5s to 0.6s.

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