On the fatigue properties of a third generation aluminium-steel butt weld made by Hybrid Metal Extrusion & Bonding (HYB)

The present investigation is concerned with the high-cycle axial fatigue behaviour of a third generation Al-steel butt weld made by Hybrid Metal Extrusion & Bonding (HYB). In this particular weld, metallurgical bonding is achieved by a combination of microscale mechanical interlocking and intermetallic compound (IMC) formation, where the IMC layer is in the sub-micrometre range (<1 mu m). During high-cycle axial fatigue testing this microstructure provides a high intrinsic resistance against interfacial cracking. In the as-welded condition, fatigue fracture typically initiates at the weld toe on the aluminium side of the joint due to the unfavourable effect of having a geometrical stress riser localised inside the soft heat-affected zone. Since the interfacial bond strength is not a limiting factor, the fatigue properties of the Al-steel HYB butt weld are seen to fully match those of corresponding Al-Al weldments produced by gas metal arc welding, laser beam welding and friction stir welding.

Automated summary

This study investigates the high-cycle axial fatigue behavior of a third generation Al-steel butt weld made by Hybrid Metal Extrusion & Bonding (HYB). The microstructure in this specific weld provides high intrinsic resistance against interfacial cracking during high-cycle fatigue testing. Fatigue fracture typically initiates at the weld toe on the aluminum side due to a geometrical stress riser localized inside the soft heat-affected zone, rather than being limited by interfacial bond strength.