Hongxin Shi

Effect of Welding Time on the Joining Phenomena of Diffusion Welded Joint between Aluminum Alloy and Stainless Steel

In the present study, direct diffusion welding of aluminum alloy 5A02 and stainless steel SUS304 has been carried out in vacuum in the welding time range of 35–110 minutes. The effect of welding time on the interfacial microstructure and tensile shear strength of the joint were investigated. The joint with tensile shear strength of 101.3 MPa was obtained under the condition of the welding time of 60 minutes. The results reveal that the reaction layer thickness increases with the increasing of welding time and that the reaction layer consists of Al5Fe2 and Al13Fe4 formed in the interface. The strength of the joint is related to the reaction layer thickness and the value of the joint strength reached maximum when the reaction layer thickness was approximately 0.8 µm.

Effects of Electrode Force on the Characteristic of Magnesium Alloy Joint Welded by Resistance Spot Welding with Cover Plates

Magnesium alloy AZ31B sheets were welded using the technique of resistance spot welding with cover plates. The effects of electrode force on the joining performance and pore formation during welding were investigated. The results reveal that the enhanced electrode force is an effective way to inhibit pore formation and improve magnesium alloy resistance spot welding performance.

Non-parametric effects on pore formation during resistance spot welding of magnesium alloy

Abstract The effects of faying surface condition, pre-existing pores in base material and cover plate on the pore formation during resistance spot welding of magnesium alloy were investigated. The results reveal that the hydrogen rejection and the pre-existing pores in base material have little effect on the pore formation, and that the larger pore formation is mainly caused by shrinkage strain during resistance spot welding of magnesium alloy.

Joining steel to aluminum alloy by resistance spot welding with a rivet

Abstract A new joining method, termed resistance spot welding with a rivet, was tried to weld steel to aluminum alloy. Scanning electron microscopy studies of the interfacial microstructures revealed the presence of an FeAl reaction layer at the rivet/aluminum alloy interface, and of FeAl3 at the steel/aluminum alloy interface. A tensile shear load of a maximum of 3.85 kN was obtained at a welding current of 21 kA. The results reveal that resistance spot welding with a rivet is an effective method for joining steel and aluminum alloy.

Microstructure and properties of Sn2.5Ag0.7Cu0.1RE lead-free soldering joints with ultrasonic assisted

Sn2.5Ag0.7Cu0.1RE/Cu solder joints were obtained with ultrasonic vibration assisted. Microstructure and properties of the joints were studied. Experimental results show that reliable soldering of Sn2.5Ag0.7Cu0.1RE/Cu can be achieved under condition of ultrasonic power of 88 W and low-halogen flux. The maximum shear strength of 26.0 MPa is obtained from the joint soldered at ultrasonic vibration time of 60 s, which increased by 35%. Compared with that of the solder joint obtained without external energy assisted, the application of ultrasonic vibration during soldering can decrease thickness and roughness of the interfacial Cu6Sn5 intermetallic compound, and the fracture mechanisms of the solder joints transforms from brittle fracture to mixed fracture, which is dominated as ductile fracture.

Joining phenomena of stainless steel/aluminium alloy joint welded by thermal compensation resistance spot welding

Aluminium alloy and austenitic stainless steel were welded using a thermal compensation resistance spot welding technology. The interface region was observed using electron microscopy, and the temperature distribution on the welding zone was investigated as well. The results reveal that higher heat can be obtained in thermal compensation resistance spot welding in comparison with conventional one, and that the morphology and thickness of the reaction layer vary with the position at the welding interface.

Solid-state bonding of superplastic ultra-high carbon steel and structure steel with an interlayer

Solid-state bonding between two superplastic steels-ultra-high carbon steel (UHCS) and a structure steel (commonly referred to as 40Cr in china; yet contains only 1 mass% Cr)- was investigated. Industry-grade pure iron sheet was used as an interlayer and the bonding was carried out at the superplastic deformation temperature T = 750 °C . For a pre-pressing stress of P = 56.6 MPa, the initial strain rate was 1.5 × 10−4s−1, and for a bonding time of t = 10min, the joint tensile strength reached up to 702 MPa a value 35% higher than what could be obtained without an interlayer. The bonding strength reached the tensile strength of 40Cr base metal through the same thermal-stress cycling. Based on the results, it was concluded that the weldability of 1.6 mass%C-UHCS / 40Cr steel was improved by using a pure iron interlayer.