Maximum Tensile Shear Force Research Articles

Effect of duty cycle on microstructure and mechanical properties of pulsed GTAW lap joint of Invar

0.7mm and 1.0mm Invar sheets in vertical position were lap-jointed by pulsed gas tungsten arc welding (pulsed GTAW). The macro morphology, microstructure and mechanical properties were studied. The feature size La (the largest weld width of lower sheet), P (the largest weld penetration of lower sheet) and R (the shortest distance from the cutting-edge of the uncombined sheets to the weld surface) are directly proportional to duty cycle. The fusion zone (FZ) is completely composed of columnar grains in which two forms of substructure are observed. Series of layer lines, which spread roughly parallel to the partially melted zone (PMZ), periodically appear in the FZ. No apparent precipitation, phase transformation and welding defects such as hot cracks are found in heat affected zone (HAZ) and FZ. Microhardness tests reveal that the microhardness of HAZ can reach more than 85% of base metal (BM), and the microhardness of FZ can reach more than 90% of BM. The effective bonding area has dominant influence on the tensile shear force in this study and the maximum tensile shear force is 4425N.

Resistance Element Welding of 6061 Aluminum Alloy to Uncoated 22MnMoB Boron Steel

A novel resistance element welding technology was applied to join 6061 Al alloy and uncoated 22MnMoB boron steel. To conduct the resistance element welding process, a technological hole was drilled in the Al sheet into which a Q235 steel rivet was inserted. Resistance spot welding was carried out at the rivet. The mechanical properties, fracture morphology, nugget formation process, dynamic resistance, microstructure, and hardness distribution of the resistance element welding were investigated. Traditional resistance spot weld joints were also prepared for comparison. Resistance spot welding could barely join Al 6061 and boron steel, and had a maximum tensile shear force of less than 1000 N. Novel resistance element welding could join the metals reliably with a maximum tensile shear force of over 7000 N and a relatively high toughness. Nugget formed at the interface of rivet and steel acted as loading position, and IMC interlayer connected rivet and aluminum.

Optimization of Parameters and Research on Joint Microstructure of Resistance Spot Welding for 316 Stainless Steel

The experimental investigations on resistance spot welding are presented for 316 stainless steel. The influence of spot welding parameters (welding time, electrode force and welding current) on the tensile shear load and the diameter of nugget have been researched, based on an orthogonal test and analysis method. The results show that welding current has significant influence on the tensile shear load and diameter of nugget, and then is electrode force, welding time in turn. The optimum parameters are as follows: welding time is 5 cycles, electrode force is 3.5KN and welding current is 5.5KA. And the maximum tensile shear force of joint is up to 13.55KN.

Optimization of Parameters and Research on Joint Microstructure of Resistance Spot Welding of 201 Stainless Steel

The experimental investigations on resistance spot welding of 201 stainless steel are presented. Experiments are carried out to study the influence of spot welding parameters (electrode force, welding current and welding time) on the tensile shear load and the diameter of nugget, based on an orthogonal test and analysis method. The optimum parameters are as follows: electrode force is 3600N, welding current is 6400A and welding time is 8 cycles. The maximum tensile shear force is up to 8920N.The microstructure of spot weld is columnar crystals in the nugget and equiaxed grains around periphery induced by non-equilibrium freezing. And the heat input has great influence on the welding defects which can cause joint quality degradation.

Study on the Resistance Spot Microwelding Parameters of Copper and Nickel-Plated Steel Dissimilar Metals

0.2-mm-thick copper and 0.3-mm-thick nickel-plated steel dissimilar metals were jointed by resistance spot microwelding. The processing parameters were optimized by orthogonal experimental and influence of processing parameter on the morphology and microstructure of welded joint was studied. The results show that the optimized processing parameters that can get the maximum tensile-shear force are: preheat current is 0.8KA, welding current is 3.5 KA, up time is 0.5ms, preheat current is 2ms, cool time is 0.5ms, welding time is 5ms, and electrode pressure is 20N. With the optimized processing parameters, the tensile-shear force of the welded joint can achieve 108.9N. The microstructures of welded joint that has best tensile-shear force are composed of swirling structure in weld nugget, uniform distribution of copper in weld nugget with a little of nickel.