Refurbishing Inconel 738 blades in GE-Frame5 gas turbines through laser cladding and welding

Subject Areas : Surface Engineering

Peyman Toosi ¹ , Hamid Zarepour ^{2 *} , Mohammad-Ali Rezaei ³

1 - Modern Manufacturing Technologies Research Center, Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
2 - Modern Manufacturing Technologies Research Center, Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
3 - Department of Materials Engineering, Tarbiat Modares University, Tehran, Iran

Received: 2024-04-08 Accepted : 2024-12-07 Published : 2024-12-12

Keywords: Laser welding, Laser cladding, Turbine blade refurbishment, Inconel 738,

Abstract :

This study aims to study the refurbishment of the first-stage Inconel 738 blades for GE-Frame 5 gas turbines through laser cladding and welding techniques. Laser welding employed a pulsed Nd:YAG system outfitted with a manual 0.7mm Inconel 625 filler wire feed. Meanwhile, laser cladding utilized a continuous fiber laser coupled to an automated powder injection system for Inconel 625. Process parameters such as scan speed, laser power output, and powder feeding rate were carefully optimized to refine the laser cladding protocol. Testing revealed laser settings of 400W power, 15g/s powder feed, and 8mm/s scan speed generated coats with superior geometry, eliminated hot cracking entirely, and minimized porosity. Preliminary welds determined optimal settings of 4mm/s scan speed at 5kW maximum power. Subsequently, 20 layers were deposited in simulation of worn blade tip repair welds. Both methods effectively reduced heat-impacted zones through refined parameters. Pulsed laser welding with filler material expanded repair options for gas turbine blades. However, surface hardness in treated areas was somewhat less than the base due to phase transformations during laser cladding and welding.

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