Effect of an electron beam surface treatment on the microstructure and mechanical properties of SAF 2205 joints produced with electron beam welding

Abstract

The aim of present investigation is to study the effect of an electron beam surface treatment on 2205 duplex stainless steel joints produced by the same electron beam process. Heat treatment of the joints is necessary, to re-establish the ferrite/austenite balance, which is extremely disturbed during the electron beam welding process. For assessing the effectiveness of the electron beam surface treatment, similar weld joints were subjected to conventional furnace heat treatment at 1050 °C, and used as reference. Metallographic techniques and mechanical testing were used to assess the microstructure and corresponding mechanical properties of the as-welded and heat treated specimens. The metallographic results showed that an austenite/ferrite ratio approaching the one produced by a typical furnace post-weld heat treatment can also be achieved by heating locally the weld surface with an electron beam. At the same time the tensile properties show considerable improvement, approaching those obtained by means of a conventional furnace heat treatment, whereas the impact strength is also improved compared to the as welded specimen, but remains clearly lower than the one of the furnace heat treated weld.