Metallographic Study of Overlapped Laser Welds of Dissimilar Materials

Abstract

The paper deals with the metallographic analysis of overlapped laser welds of dissimilar materials based on galvanized and ungalvanized steels in various combinations. In addition to a gallery of metallographic sections, the paper presents the monitoring of weld defects, the measurement of selected weld geometrical characteristics and changes in weld microstructure by measuring the microhardness profile across the joint. The mixing of materials was monitored by area and line EDX analysis in the melting zone. Subsequently, the load carrying capacity of the formed joints was determined and compared with FEM simulation. Finally, the dependences of hardness and strength of welds on carbon content and carbon equivalent were determined.

Microstructure and mechanical properties of fibre laser welded joints of CP780 and TRIP690 steel

“…These steel grades can utilise several sophisticated strengthening mechanisms, including martensite transformation during straining. These steel grades, representing the first generation of AHSS, have found the most application in the body in white applications [1][2][3][4][5][6]. The DP steels exhibit dual ferrite martensite microstructure.…”

Experimental Study of Steel–Aluminum Joints Made by RSW with Insert Element and Adhesive Bonding

“…Welding involves the different melting temperatures of the materials, resulting in the formation of brittle intermetallic compounds at the steel–Al alloy interface [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. Many authors [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ] have taken the route of reducing the heat input during welding [ 3 , 4 , 5 , 6 , 7 , 15 , 16 ], thereby reducing the thickness of brittle IMCs, or have taken advantage of the better solubilities of Al and Zn compared to the very low solubilities of Fe and Al and have used the zinc interlayer and the associated eutectic reaction for joining [ 8 , 9 , 10 , 11 , 12 , 13 ].…”

“…Welding involves the different melting temperatures of the materials, resulting in the formation of brittle intermetallic compounds at the steel–Al alloy interface [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. Many authors [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ] have taken the route of reducing the heat input during welding [ 3 , 4 , 5 , 6 , 7 , 15 , 16 ], thereby reducing the thickness of brittle IMCs, or have taken advantage of the better solubilities of Al and Zn compared to the very low solubilities of Fe and Al and have used the zinc interlayer and the associated eutectic reaction for joining [ 8 , 9 , 10 , 11 , 12 , 13 ]. Experiments were carried out focusing on a reduction in the IMC layer thickness using an ultrasonic-resistance welding process or a novel projection welding technology, consisting of joining an insert element (a short piece of welding filler of suitable composition) to an aluminum plate and then joining the aluminum plate to the steel plate using RSW technology [ 17 , 18 ].…”