Surface quality and Tool Wear Analysis in AISI D2 Tool Steel Hard Turning: A Comprehensive Review of Cooling Techniques

Abstract

Due to its low heat conductivity and strong resistance to wear, AISI D2 tool steel, recognized for its high level of hardness (58-62 HRC) and complex structure with tough carbides, poses significant challenges in machining. A review of 106 freely available studies from 2020 to 2026 examines hard turning operations on D2 steel, focusing on surface roughness, surface quality, and tool wear. The study evaluates various cooling and lubrication methods including dry cutting, flood coolant, minimum quantity lubrication (MQL), nanofluid-MQL, cryogenic cooling, hybrid techniques, and high-pressure coolant. The research identifies feed rate as the primary factor influencing surface roughness, explaining a substantial portion of the observed variations. It highlights the effectiveness of hybrid cryogenic-MQL and Nanofluid-MQL treatments in increasing tool lifespan by 80-400% compared to dry cutting while enhancing surface finish. The article also identifies seven critical research gaps such as the need for a deeper understanding of white layer formation during cryogenic cooling and the stability evaluation of nanofluids. Keywords: AISI D2 tool steel; hard turning; surface roughness; surface integrity; tool wear; MQL; nanofluid; cryogenic cooling; white layer; residual stress; CBN;