Analysis of the main types of damage on a pair of industrial dies for hot forging car steering mechanisms

The paper presents an analysis of the main types of damage on industrial upper and lower hot-forging dies for hot forging of car steering mechanisms. The dies were previously gas nitrided at various conditions and exhibit various microstructures after nitriding. They failed after a different number of forging strokes. Measurements of microhardness depth profiles and examinations of nitrided layers with an optical microscope were conducted. The design of die shape in sequential forging steps has the predominant role for a prolonged die life in comparison to the quality of nitrided die cavity surface. Improvements of die cavity design as well as improvements of nitriding process are suggested.