1 Risø National Laboratory for Sustainable Energy, Technical University of Denmark2 Department of Mechanical Engineering, Technical University of Denmark
Three fractured tool dies used for industrial cold forging have been investigated using light optical microscopy and scanning electron microscopy. Two of the specimens were produced using the traditional Böhler P/M steel grade s790, while the lastspecimen was a third generation P/M steel produced using new technology developed by Böhler. All three steels have the same nominal composition of alloying elements. The failure in both types of material occurs as a crack formation at a notch inside ofthe tool. Generally the cold forging dies constructed in third generation steels have a longer lifetime than the ones constructed in traditional steel, which is connected to differences in micro-structure. Focus has been put on differences in the size anddistribution of car-bides. It is found that the third generation steel contains smaller and more finely dis-persed carbides and has an increased resistance towards abrasive wear compared with the traditional P/M steel.