Study on the metallurgical structure characters of sub-surface layer of ultra-high strength alloy steel in high speed milling condition

With the cutting speed of 157-314 m/min, by use of 2^3-1 factorial design, the high speed dry face-milling experiments were carried out on an ultra-high strength alloy steel, a type of difficult-to-cut materials used widely in ordnance industry. Beside the regularity of cutting parameter on surface roughness, the characters of metallurgical structure and microhardness distribution in work-piece's sub-surface layer were also discussed. It was concluded that, when high speed milling of this ultra-high strength alloy steel, the cutting parameter had remarkable effects on the metallurgical structure of sub-surface layers; the effects were plastic deformation, over tempered martensite, under tempered martensite etc.; larger feed per tooth in high speed milling process could bring unremarkable influence on the metallurgical structure of sub-surface layers.