Galling resistance and wear mechanisms – cold work tool materials sliding against carbon steel sheets

Abstract

One of the major causes for tool failure in sheet metal forming is transfer and accumulation of adhered sheet material to the tool surfaces, generally referred to as galling. In the present work, the galling resistance of several tool materials was investigated against two-phase ferritic-martensitic carbon steel under dry sliding test conditions. Tribological evaluation was carried out at different contact pressures by using a slider-on-flat-surface (SOFS) tribometer. For all selected test conditions, a consistent ranking of the materials was obtained with best performance observed for nitrogen alloyed powder metallurgy tool steel. Worst galling resistance was observed by nodular cast iron.

Wear Mechanisms in Galling: Cold Work Tool Materials Sliding Against High-strength Carbon Steel Sheets

“…The duration of each regime depends on both tool microstructure and heat treatment and sheet material. In [1], similar tool materials were investigated in sliding against medium-strength carbon steels using the SOFS tribometer. Compared to the high-strength carbon steel used throughout this study, the first regime was substantially longer.…”

“…The damage is of high concern for the forming industry and particularly for the sheet metal forming society. In general, galling is a multi-stage process [1][2][3][4], distinguished as a sequence of events with an initial stage of local transfer of sheet material to the tool surface. Subsequent forming operations lead to growth of the transfer layer and initiation of a second stage with scratching of the work piece.…”

“…Especially carbon-based DLC coatings have shown promising results in both lubricated and unlubricated systems [10,14,18]. Recently, nitrogen alloying of powder metallurgy (PM) tool steels, for formation of V(C,N) particles, has gained a lot of attention because significant improvement in tool's lifetime is achieved [1,15,19]. However, the governing mechanisms owing to the improvements have not yet been fully explored.…”

“…The SOFS tribometer, which utilizes a disc-shaped tool slid over a real sheet surface, has been efficiently used for galling evaluation [1,2]. For example in [1], mediumstrength steel sheets were used for tests in dry sliding test conditions.…”

“…For example in [1], mediumstrength steel sheets were used for tests in dry sliding test conditions. It was found that changes in the galling stages may be detected by changes in friction.…”