Novel Cutting-Edge In-situ Deposition of Soft Metallic Solid Lubricant Coatings for Efficient Machining of High-Strength alloys

Abstract

Inconel 718 has widespread use in critical industries like aerospace, marine, and power generation. However, its challenging machinability, characterized by tool chipping/failure, and poor surface quality, remains a significant concern. Despite numerous efforts to enhance tool performance in machining hard-to-machine materials, the issue of sudden tool failure and chipping persists. This study presents an innovative in-situ tool treatment method, complemented by an optimized recoating strategy, aimed at tackling these challenges. The approach involves the application of a lubricating soft metallic Al-Si alloy coating to the tool’s faces, which can be recoated when needed. During subsequent Inconel machining, the Al-Si layer deposited on the tool melts due to high temperatures. The molten material fills microcracks on the tool surface, preventing their propagation. Moreover, the tool can slide on the beneficial tribo-films Al-Si layer which reduces friction, sticking, seizure, and built-up edge formation, resulting in decreased tool wear and chipping. The newly developed pre-machined recoating method has yielded promising outcomes, reducing cutting force and significantly improving tool lifespan compared to the PVD benchmark and uncoated tools. Additionally, this novel method enhances surface quality and minimizes undesirable microstructural alterations induced by machining.