A microstructural and low-cycle fatigue investigation of weld-repaired heat-resistant cast steels

Abstract

WeldingCracking Low-cycle fatigue a b s t r a c tThe multi-pass weld-repair of heat-resistant cast steels is carried out using an automated shielded metal arc welding (SMAW) process, with various filler materials and pre-heating at 400 • C. Specimens weld-repaired with a filler material more resistant than the heat-resistant cast steel (over-matching) generally crack within the base metal following the tenth filling pass, whereas specimens buttered with a soft alloy prior to welding remain free of cracks.The high temperature strain-controlled fatigue lifetime of material weld-repaired without buttering is lower than that of bulk initial material. This is due to an increase of the stress amplitude as a result of the so-called over-matching. In the case of material welded following a prior buttering, the fatigue lifetime is reduced because of the stress tri-axiality generated in the thin soft layer which prevents its plastic flow. As a consequence, it is concluded that even though buttering prevents cracking efficiently during welding, it is not acceptable as far as fatigue performance, especially lifetime, is concerned.

Welding of Aluminum Alloys

“…Fatigue behavior of aluminum alloys welded by conventional process has been investigated by some authors (Ambriz et al 2010b;Branza et al, 2009;Seto et al, 2004). In terms of fatigue behavior considering FSW, some interesting studies have been published (Matic & Domazet, 2005, Chiarelli et al, 1999, James & Paterson, 1998.…”

Analysis of weld-cracking and improvement of the weld-repair process of superplastic forming tools

“…This method allowed, under special conditions, to prevent cracking during weld-repair of 20 mm deep V-grooves. However, the fatigue life time of such repairs was very low [9], so other weld-repair techniques have to be investigated for weld-repair SPF dies.…”

“…However, recent works have shown that weld repair samples obtained with buttering technique have very low fatigue life time, so this repair process is not convenient for SPF dies [9].…”

Fusion Welding with Indirect Electric Arc

“…Fatigue behavior of aluminum alloys welded by conventional process and MIEA has been investigated (Ambriz et al 2010b;Branza et al, 2009;Seto et al, 2004). Fig.…”