TWI Industrial Member Report Summary 1080/2017
By Robert Shaw
Precipitation-strengthened nickel alloys are commonly used for cast components in the aero-engine and power generation industries. The components are of high value, such that their scrappage can have a significant economic impact. Therefore, it is desirable to be able to perform arc weld repairs on these components, particularly in low stress regions in which post-weld heat treatment might be deemed unnecessary.
Precipitation-strengthened nickel alloys have a range of weldability with weld cracking susceptibility being often well correlated with aluminium and titanium content. Alloys containing more than six atomic percent combined aluminium and titanium are generally considered unweldable. This includes alloys which are widely used, like Mar-M247 and Alloy 713C, in which TWI’s Industrial Members have expressed an interest.
Previous work on these alloys has shown significant difficulty in performing weld repairs without solidification or liquation cracking, so this body of work was initiated with the intent of investigating process space not yet explored. A literature review was undertaken, ‘Shaw, 2013: TWI Technical Literature Review 22954: A Review of Weld Repairs of Mar-M247 and Similar Alloys’, which set the direction of this work.