A method is provided for repairing degraded and/or eroded areas on gas turbine blades and vanes. The method is directed to turbine blades and vanes made of advanced superalloy materials with high elevated-temperature properties. The method uses multiple laser beams to perform steps of preheating the repair area, welding the repair area, and post-welding heating of the repaired area. The method uses an array of two or more lasers to perform the steps of heating, welding, and post-weld heat treatment in nearly simultaneous operation thereby dramatically reducing or eliminating the hot cracking associated with other welding methods used with superalloy materials. The method is further directed to cladding or material buildup of degraded turbine blades where the weld material is the same as the matrix or better superalloy materials.

Multi-laser beam welding high strength superalloys

A process for producing a crack-free and dense three-dimensional article of a gamma-prime precipitation-strengthened nickel-base superalloy, with more than 6 wt. % of [2 Al (wt. %)+Ti (wt. %)], which involves: (a) preparing a powder layer of a gamma-prime precipitation-strengthened nickel-based alloy material, with uniform thickness on a SLM apparatus substrate plate, or on a previously processed powder layer; (b) melting the prepared powder layer by scanning with a focused laser beam an article cross section area according to a three-dimensional sliced model with calculated cross sections, stored in the SLM control unit; (c) lowering the substrate plate by one layer thickness; and (d) repeating (a) to (c) until reaching a final cross section according to the three-dimensional sliced model, wherein, for (b), the laser power, focus diameter of the focal spot, and scan speed of the focused laser beam are adjusted to obtain heat dissipation welding.

A process for the production of articles made of a gamma-prime precipitation-strengthened nickel-base superalloy by selective laser melting (SLM)

A laser repair method for a high gamma prime content Ni base superalloy substrate surface, with gamma prime content in the range of at least about 30 volume %, conducts the repair at ambient temperature without preheating the substrate surface and by controlling processing parameters to avoid cracking of the resulting weld bead during and after welding. The laser beam, operating in a power range of about 50-10000 watts per centimeter, is focused away from the substrate surface to provide a laser spot in the size range of about 0.03-0.2″. A relative movement between the substrate surface and the laser beam, for example at a rate in the range of about 1-100 inches per minute, provides an interaction time of no greater than about 10 seconds between the laser beam and the substrate surface. Concurrently, a repair alloy powder is deposited in the laser beam to melt and fuse the repair alloy powder into a molten repair alloy deposited on the substrate surface.

Laser repair method for nickel base superalloys with high gamma prime content

A method is disclosed for removing casting defects (5) from an article (1) with an oriented microstructure. The method comprises the steps of locating at least one casting defect (5) and melting the casting defect (5) locally by a heat source (7) to a depth at least as great as the casting defect (5) itself. Subsequently the molten material is solidified epitaxially with respect to the surrounding oriented microstructure of the article (1) in a way that the resulting solidified area is substantially free of any defect.

Method of removing casting defects

A welding method for welding workpieces made of highly heat-resistant superalloys is provided. The method includes generating a heat input zone on the workpiece surface by means of a heat source, feeding welding filler material into the heat input zone by means of a feeding device, and generating a relative motion between the heat source and the feeding device on one hand and the workpiece surface on the other hand by means of a conveying device. Furthermore, according to the welding method, the mass feed rate is ≦350 mg/min.

Method for welding workpieces made of highly heat-resistant superalloys, including a particular mass feed rate of the welding filler material

A process is provided for laser welding a nickel or cobalt based superalloy article to minimize cracking by preheating the entire weld area to a ductile temperature, maintaining such temperature during welding and solidification of the weld, with the welding utilizing a powder alloy feed and the speed of the laser controlled to less than 10 inches per minute.

D. Lovelace

Papers

Laser welding superalloy articles

Laserschweissen von artikeln aus superlegierungen