Surface Chemical Analysis of Pretreatment by Shot Blasting Prior to Environmentally Friendly Lubrication for Cold Forging and Estimation of Its Lubrication Performance

Abstract

For lubrication in cold forging, pretreatment by shot blasting to workpieces is widely used to prevent galling and realize high lubrication performance for replacing conventional conversion coatings with environmentally friendly lubricants. Previous studies suggest that an appropriate surface topography on workpieces pretreated by shot blasting improves lubricant adhesion and lubrication performance. Shot blasting generates not only an appropriate surface topography but also freshly activated surfaces on workpieces. In this study, results of surface chemical analysis by X-ray absorption near edge structure (XANES) on a steel surface which is conducted pretreatment by shot blasting and lubricant application. In the lubrication, an environmentally friendly lubricant with phosphorus extreme-pressure additives is used under conditions of different interval times after shot blasting. It was found that lubricant application immediately after pretreatment by shot blasting raised the potential of lubrication performance, as shown by the results of the ball penetration test.