In Situ and Post-Mortem Characterizations of Ultrasonic Spot Welded AZ31B and Coated Dual Phase 590 Steel Joints

Jian Chen,Donovan Leonard,Hui Huang,Xin Sun,Yong Chae Lim,Zhili Feng

doi:10.3390/met10070899

Abstract

Ultrasonic spot welding using different welding conditions was applied to join dissimilar metals of galvanized DP590 steel and AZ31B magnesium sheets. In situ high-speed imaging, digital image correlation, and infrared thermography were utilized to quantitatively study the interfacial relative motion, surface indentation, and heat generation across the joint faying interface and the sheet/sonotrode interfaces under the welding condition of moderate welding power and short welding time. For welds made with high power and long welding time, lap shear tensile tests as well as fatigue tests were carried out. Different fracture modes were observed after the lap shear tensile tests and fatigue tests performed under different peak loads. Post-weld cross-sectional analysis with scanning electron microscopy coupled with energy dispersive X-Ray spectroscopy revealed the variation of morphology and chemical composition at the joint interface for welds made with different welding conditions.

Highlights

With increasing demand of lightweight materials in automobiles to reduce fuel consumption and greenhouse gas emissions, magnesium (Mg) alloys have received much attention due to their low density and high specific strength [1]
Interfacial Relative Motion, Surface Indentation, and Heat Generation In Experimental Setup 1 as listed in Table 1, the displacement of the sonotrodes and the metal listed in Table 1, of the sonotrodes and theofmetal sheets monitored by the approach
It the wasdisplacement found that the oscillation amplitude both sheets were during monitored by the

Summary

Introduction

With increasing demand of lightweight materials in automobiles to reduce fuel consumption and greenhouse gas emissions, magnesium (Mg) alloys have received much attention due to their low density and high specific strength [1]. Joining Mg alloys with steel structures is challenging. This is because the physical and chemical properties of these two materials are quite different. The melting point of Mg is 650 ◦ C versus steel or iron (Fe) at approximately 1500 ◦ C. The solubility between them is very low. One effective way to metallurgically join Mg and steel is to obtain an interlayer. The elements of the interlayer can be from the alloy elements of the base metals or by adding a layer of coating material such as zinc (Zn) [2]

Methods

Results

Conclusion