Improved tool wear properties in sheet metal forming using Carbide Steel, a novel abrasion resistant cast material

Abstract

This work presents a comparative study regarding wear behavior between a novel abrasion resistant cast iron, “Carbide Steel” and a number of conventional tool materials frequently used in the automotive industry. Carbide Steel is basically a high-Cr white cast iron heavily alloyed with cemented carbide. The high chromium content and additional alloying elements like WC, TiC or NbC results in a material containing a large portion of hard, wear-resistant carbides with a composition different from conventional white irons normally used in wear applications. Characteristic properties for the material are: superior as-cast properties, improved wear resistance and hardness. The as-cast hardness of Carbide Steel is comparative to hardened steel but depending on desirable properties of the wear part the alloying content can be varied within a wide range. An interesting aspect of the material is potential for sustainable manufacturing, due to the fact that the critical alloying elements are added in the form of recycled carbide inserts. The experimental work was carried out in a U-bending test equipment to simulate conditions in a stamping process. One type of sheet material was used and seven different conventional tool materials were evaluated. The selection of tool materials ranged from white cast irons to tool-steels and powder steels. The wear patterns were analyzed and expressed in percentages of reduction of weight of the test specimens, galling tendency and temperature variations during the experiments. All parameters were correlated to the number of strokes. The press force was measured and a friction coefficient was calculated. An important conclusion from the experimental work is that Carbide Steel has a significantly higher wear resistance compared to the other conventional tool materials evaluated. Galling is also significantly reduced when using Carbide Steel. The volume part of carbides and the relative size of the same play a significant role in the process leading to less galling and wear, when using Carbide Steel as a tool material.