Laser additive repairing of nickel base superalloy components

摘要

Ni base superalloy components containing relatively large amounts of Al and Ti are known to be difficult to build up by a weld build up process without cracking. As the Al and Ti content of the superalloy is increased to improve the strength, the susceptibility to cracking is increased. It is shown herein that reducing the γ′ phase in the additive built up material improves robustness against cracking. A stepwise, controlled heating and cooling process is described to be used in cooperation with an additive build up process to reduce the γ′ present and thereby reduce cracking.

主权项

1. A method of repair additive build up of a nickel (Ni) base superalloy with significant titanium (Ti) and aluminum (Al) content comprising:
a) preplacing a Ni base superalloy powder having significant Ti and Al content onto a substrate of the same composition as the Ni base superalloy powder; b) preheating the preplaced powder to a temperature above 1200 deg. C. with a first heat source; c) melting the preplaced powder with one or more passes of a directed energy beam second heat source so as to produce a heat affected zone having a width less than 100 microns, removing the second heat source when melting is completed; d) performing a controlled step and hold cooling of the melted preplaced powder with the first heat source such that no more than 20 weight percent of γ′ phase is formed during the step and hold cooling.