Accession Number : AD0728827

Title :   Machining of High Strength Steels with Emphasis on Surface Integrity.

Descriptive Note : Technical rept.,

Corporate Author : AIR FORCE MACHINABILITY DATA CENTER CINCINNATI OHIO

Personal Author(s) : Field,Michael ; Koster,William P. ; Kohls,John B. ; Snider,Robert E. ; Meranchik,John , Jr

Report Date : MAY 1970

Pagination or Media Count : 276

Abstract : As the strength level of High strength steels increases, fatigue and stress corrosion resistance exhibit a marked increase in sensitivity to surface conditions produced in machining. There are several significant surface alterations produced in machining which can seriously affect fatigue and stress corrosion resistance. These include untempered martensite, overtempered martensite, plastic deformation, cracks, tears, laps, burrs, spattered or redeposited metal, and residual stress. The effect of machining conditions on the formation or avoidance of these surface alterations is discussed in detail. Machining relationships and recommendations are given for chip removal operations, abrasive operations, as well as nonconventional operations, to minimize surface alterations. To maintain high surface integrity in milling, turning, drilling, etc. machining conditions are selected to provide long tool life. In addition, tools must be kept sharp, that is, tools must be changed frequently to minimize metallurgical alterations within the surface layer. In grinding, low wheel speeds, light down feeds, together with the use of highly active cutting oils are necessary to minimize surface alterations. Post-operative machining processes, such as heat treatment and shot peening are often needed to obtain desirable surface conditions. Rigid inspection techniques and often repair procedures are required to insure proper surface integrity. Particular attention is given to the problem of drilling and reaming holes with high surface integrity in high strength steels. (Author)

Descriptors :   (*MACHINING, *STEEL), SURFACE PROPERTIES, FATIGUE(MECHANICS), STRESS CORROSION, CORROSION RESISTANCE, QUALITY CONTROL, STRESSES, DISTORTION

Subject Categories : Fabrication Metallurgy

Distribution Statement : APPROVED FOR PUBLIC RELEASE