Strategies for Increasing the Productivity of Pulsed Laser Cladding of Hot-Crack Susceptible Nickel-Base Superalloy Inconel 738 LC

Abstract

A novel repair strategy based on decoupled heat source for increasing the productivity of wire-assisted pulsed laser cladding of the γ’-precipitation strengthening nickel-base superalloys Inconel 738 low carbon (IN 738 LC, base material) and Haynes 282 (HS 282, filler material) is presented. The laser beam welding process is supported by the hot-wire technology. The additional energy is utilized to increase the deposition rate of the filler material by increasing feeding rates and well-defining the thermal management in the welding zone. The simultaneous application of laser pulse modulation allows the precise control of the temperature gradients to minimize the hot-crack formation. Accompanying investigations such as high-speed recordings and numerical simulations allow a generalized statement on the influence of the adapted heat management on the resulting weld seam geometry (dilution, aspect ratio and wetting angle) as well as the formation of hot-cracks and lack of fusion between base and filler material. Statistical analysis of the data—the input parameters like laser pulse energy, pulse shape, hot-wire power and wire-feeding rate in conjunction with the objectives like dilution, aspect ratio, wetting angle and hot-cracking behavior—revealed regression functions to predict certain weld seam properties and hence the required input parameters.

The Relevance of Process Parameter Optimization and Geometric Figure for Direct Laser Deposition of Inconel 738 Alloy and Its Theoretical Modeling

“…At present, the inclusion cracking issue of Inconel 738 alloy can be addressed through three main approaches: optimizing the powder composition, optimizing the process parameters of laser additive manufacturing, and incorporating physical field technology. It has attracted great attention in various fields, and related research work has been carried out [3][4][5]. Compared to other popular alloys, such as Inconel 718, Inconel 600, Monel 400, and Ti6Al4V, Inconel 738 holds a greater economic and industrial significance.…”

Investigation of the γ′ Precipitates Dissolution in a Ni-Based Superalloy During Stress-Free Short-Term Annealing at High Homologous Temperatures

“…[12] Preheating temperature and time, i.e., the influence of short-term heat treatment cycles on nickel superalloy's microstructure changes, is a particularly important area in designing new technologies, as welding processes are widely used for regenerating foundry defects and repairing of serviced components. [13][14][15][16] Hot cracking, including liquation cracking in the heat-affected zone, is directly dependent on the c¢ behavior during heating and subsequent cooling. Superalloys with more than 40-50 pct of c¢ precipitates are commonly considered as difficult to weld.…”