Wear performance assessment of alternative stamping die materials utilizing a novel test system

Abstract

Stamping of Ultra/Advanced High Strength Steel (U/AHSS) sheets leads to high contact stresses and non-uniform strains. These, in turn, cause high wear rates and springback. In order to prevent the excessive wear effect in stamping dies, various countermeasures have been proposed such as alternative coatings, modified surface enhancements in addition to the use of newer die materials including cast, cold work tool, and powder metallurgical tool steels. A new slider type of test system was developed to replicate the actual stamping conditions including the contact pressure state, sliding velocity level and continuous and fresh contact pairs (blank-die surfaces). A vertical machining centre, with vertical and normal force sensors mounted on its spindle, was employed to generate the contact pressure and controlled movement of die samples on sheet blank. Several alternative die materials in coated or uncoated conditions were tested against different AHSS and stainless steel blanks under certain load, sliding velocity, lubrication circumstances. This paper briefly describes the test system and experimental methodology, and presents the results for wear resistance performance of an air-hardening cold-work tool steel sample with different coatings tested against DP 600 AHSS grade sheet blanks.