Analysis of Degradation and Failure Mechanisms that Develop in Hot Forging Die
A failed die, used to forge gas valves, was analyzed using macroscopic and microscopic equipment on some specimens. Fatigue cracks on the die were evidently observed on all the surfaces of the die. Many processes were found to be major contributors to have caused the die failure. Oxidation was observed in some areas, especially on plane surfaces and thin sections. Surface layers of tools at the tool-workpiece interface were not only exposed to high mechanical stresses but also to severe temperature cycles, which could have led to loss of strength and hardness. Metallographic analysis revealed that the oxide layers consisted of different diffusion layers which accelerated thermal fatigue mechanisms.
KeywordsDegradation Forging Wear Fatigue Die
The authors wish to thank the management and the employees of SOPAL Society for their cooperation and assistance in the preparation of samples for laboratory analysis.
- 6.Njeh, F., Kchaou, M., Elleuch, R., Hallouani, F.: Failure modes of die used for hot forging. In: Premier Congrès Tunisien de Mécanique (COTUME 2008), Hammamet, 17–19 Mar 2008Google Scholar
- 8.Kchaou, M., Elleuch, R., Desplanques, Y., Boidin, X., Degallaix, G.: Etude du comportement de l’acier X40CrMoV5-1 pré-oxydé en frottement-usure sous faible vitesse de glissement. Ann. Chim. Sci. Mater. 35(1), 41–57 (2010)Google Scholar
- 13.Spera, D.A.: What is thermal fatigue? Thermal fatigue of materials components. In: ASTM STP 612, pp. 3–9. ASTM, Philadelphia (1976)Google Scholar