High-Strength titanium laser welding with a subsequent combination of mechanical and laser heat treatment

Abstract

Titanium and its alloys are characterized by a high specific strength and extraordinarily good corrosion resistance; therefore, welded titanium parts show a high potential in the aerospace industry and in chemical plants for pipeline and tank constructions. At present, an increasing use of titanium materials can be observed in the automotive industry, e.g. for exhaust systems or high performance engines. Although high-strength pure titanium materials are considered to be weldable, the welding application potential is limited, due to strongly decreased ductility based on disadvantageous microstructures in the welding seam and the heat affected zone.A newly-developed process based on a subsequent mechanical and pyrometer-controlled laser heat treatment of laser welds for titanium allows exact control of the welding seam microstructure.The mechanical characteristics of welding seams, especially ductility and the associated formability, could be improved almost up to the base material level by refining the grain. At the same time, mechanical strength could be maintained. This permits the manufacturing of high-strength welded titanium constructions, which could not be manufactured up to now, due to unsatisfactory ductility of the welding seams.Titanium and its alloys are characterized by a high specific strength and extraordinarily good corrosion resistance; therefore, welded titanium parts show a high potential in the aerospace industry and in chemical plants for pipeline and tank constructions. At present, an increasing use of titanium materials can be observed in the automotive industry, e.g. for exhaust systems or high performance engines. Although high-strength pure titanium materials are considered to be weldable, the welding application potential is limited, due to strongly decreased ductility based on disadvantageous microstructures in the welding seam and the heat affected zone.A newly-developed process based on a subsequent mechanical and pyrometer-controlled laser heat treatment of laser welds for titanium allows exact control of the welding seam microstructure.The mechanical characteristics of welding seams, especially ductility and the associated formability, could be improved almost up to the base material level by refining the gr...