Masoud Harooni

Welding of Aluminum Alloys to Steels: An Overview

Abstract Since the need for the joining of dissimilar materials is increasing, the wide range of requirements of the numerous industries would lead to the development of new welding techniques or at least to improvement of the existing technologies capable of joining the components from the miniature assemblies to extremely large earth-moving vehicles. Among the different materials, iron-based alloys and aluminum-based alloys are the most significant materials that are finding applications in the various industries to offer more viable and sustainable products. However, welding of these metals has been always a kind of dilemma for the engineers. There are a certain number of methods to join these dissimilar metals but no one could establish a reliable or a sort of credible welding method for the industrial applications while quality, cost, human resources and facilities are taken into the main considerations. This paper reviews the recent works on the joining of different aluminum alloys to different steels. The effect of the joining conditions on the formation of intermetallics and microstructural development, mechanical properties and applications of the joints are discussed.

Mitigation of Pore Generation in Laser Welding of Magnesium Alloy AZ31B in Lap Joint Configuration

Magnesium, as the lightest structural metal, has been widely used in the automotive and aerospace industries. Porosity is the main issue in the welding of magnesium alloys and can be caused by surface coatings, hydrogen gas, pre-existing porosity, the collapse of an unstable keyhole and vaporization of alloying elements. In this study, the effect of the oxide layer on pore generation in the welding of AZ31B-H24 magnesium alloy is investigated. A fiber laser with a power of up to 4 kW is used to weld samples in a lap joint configuration. Two groups of samples are studied: as received (AR) surfaces (where an oxide layer remains on the surface) and treated surfaces. The surface treatment includes two techniques: mechanical removal (MR) and the use of a plasma arc (PA) as a preheating source. Also, a separate set of experiments are designed for preheating samples in a furnace in order to investigate whether the pore mitigation effect of a plasma arc is caused by preheating. Observations include a weld bead profile achieved through optical microscopy, chemical compositions tested by Electron Dispersive Spectroscopy (EDS), and mechanical properties measured with a tensile test. The results obtained show that the preheating effect of a plasma arc procedure can effectively mitigate pore generation. The tensileshear results reveal that PA samples have a higher strength than other groups of samples.

Effect of Process Parameters on the Weld Quality in Laser welding of AZ31B Magnesium Alloy in Lap Joint Configuration

Magnesium is the lightest structural metal; therefore it has been used in a variety of industries such as automotive, aerospace, electronics and defense. Among different joining processes, laser welding is advantageous due to its low heat input, high depth-to-width weld ratio and good mechanical properties. In this study, a fiber laser is used to weld AZ31B magnesium alloy in a lap joint configuration. Pores were formed in the weld bead that are caused by a thick oxide layer existing on the surface of as-received AZ31B samples. Process parameters including laser power and welding speed are studied to determine their effects on pore formation and maximum lap-shear load of the weld bead. Hardness and tensile tests are carried out to reveal the mechanical properties of the weld bead. A regression analysis is performed that establishes a mathematical relation between the process parameters and the weld maximum lap-shear load. Three regression models are compared in order to determine their accuracy in prediction of the maximum lap-shear load and results revealed that the linear model could best predict the maximum lap-shear load by process parameters.Magnesium is the lightest structural metal; therefore it has been used in a variety of industries such as automotive, aerospace, electronics and defense. Among different joining processes, laser welding is advantageous due to its low heat input, high depth-to-width weld ratio and good mechanical properties. In this study, a fiber laser is used to weld AZ31B magnesium alloy in a lap joint configuration. Pores were formed in the weld bead that are caused by a thick oxide layer existing on the surface of as-received AZ31B samples. Process parameters including laser power and welding speed are studied to determine their effects on pore formation and maximum lap-shear load of the weld bead. Hardness and tensile tests are carried out to reveal the mechanical properties of the weld bead. A regression analysis is performed that establishes a mathematical relation between the process parameters and the weld maximum lap-shear load. Three regression models are compared in order to determine their accuracy in predict...

Studying the Effect of Laser Welding Parameters on the Quality of ZEK100 Magnesium Alloy Sheets in Lap Joint Configuration

Magnesium has unique properties which makes it superior to many other metals. It has the best strength-to-weight ratio and the lowest density among structural metals. Therefore, it has been used in a variety of industries, including the automotive, aerospace, and electronics industries. However, because of magnesium metallurgical properties, fusion welding poses a significant challenge. Laser welding is one of the most efficient joining processes for welding magnesium alloys because of its low heat input. Low alloy magnesium ZEK100 has been used in the automotive industry; however, little research has been published on the welding of this alloy. In this study, a fiber laser is used to weld samples in a lap joint configuration in order to study the effect of process parameters on weld profile geometry including penetration depth and width on top surfaces and interfaces as well as its quality. Process parameters include laser power, scanning speed and gap between two sheets. Observations include weld bead surface quality, weld bead profile and micro-hardness. The obtained results show that each process parameter has a different effect on weld profile geometry and its quality. Then a regression model is used in order to obtain the geometry of the weld bead based on different process parameters. The performance evaluation of the regression model reveals that a well-related model is established.Magnesium has unique properties which makes it superior to many other metals. It has the best strength-to-weight ratio and the lowest density among structural metals. Therefore, it has been used in a variety of industries, including the automotive, aerospace, and electronics industries. However, because of magnesium metallurgical properties, fusion welding poses a significant challenge. Laser welding is one of the most efficient joining processes for welding magnesium alloys because of its low heat input. Low alloy magnesium ZEK100 has been used in the automotive industry; however, little research has been published on the welding of this alloy. In this study, a fiber laser is used to weld samples in a lap joint configuration in order to study the effect of process parameters on weld profile geometry including penetration depth and width on top surfaces and interfaces as well as its quality. Process parameters include laser power, scanning speed and gap between two sheets. Observations include weld bead s...

Laser Welding of Magnesium Alloys: Issues and Remedies

Automotive industry tends to use lightweight alloys to save on mass in order to have more economic and environment friendly automobiles. A variety of alloys have been used in automotive industry such as magnesium, aluminum, and galvanized steel. Magnesium is the lightest structural metal that can significantly help decrease the body structure weight. Laser welding is one of the main joining processes used in automotive industry due to its superior joint properties. In the current study, the main issue that was pore formation during the laser welding of magnesium alloy is investigated. First, the process was performed using different process parameters to study their effect on the weld quality. Then a variety of approaches were used to mitigate pores in the weld. The results showed that these approaches could effectively mitigate pore formation in the weld bead. In addition, the pore formation issue was nondestructively detected using real‐time methods such as spectrometer and high speed charge‐coupled device (CCD) camera. The results showed that there was a good correlation between pore for‐ mation and the real‐time‐monitoring detected data.