Fatigue Failure of Extrusion Dies: Effect of Process Parameters and Design Features on Die Life
- PDF / 767,971 Bytes
- 12 Pages / 595.276 x 790.866 pts Page_size
- 12 Downloads / 296 Views
TECHNICAL ARTICLE—PEER-REVIEWED
Fatigue Failure of Extrusion Dies: Effect of Process Parameters and Design Features on Die Life S. S. Akhtar • A. F. M. Arif
Submitted: 3 May 2009 / Published online: 26 November 2009 ASM International 2009
Abstract Analysis of die failure plays an important role in the prediction and prevention of die failure, and subsequently in improving economics of any metal-forming process. Industrial experience has shown that fracture is the most common mode of failure in the case of hot aluminum extrusion dies. The purpose of the present work is to implement fatigue damage models in a Finite Element code for identification of critical process parameters and die design features in the case of fatigue being the dominating failure mode. For the maximum number of billets extruded by the die before fatigue crack initiation (fatigue life cycles in extrusion), Morrow’s stress- and strain-life damage models are implemented for axisymmetric flat extrusion die. With the help of finite element software ABAQUS, extrusion process is simulated and dynamic stress and strain values were obtained by first identifying the potential fatigue location in the die. The evaluation of applicability of the damage models is done for specific hot extrusion die made of H13 steels with Al-6063 as billet material. By considering temperature and strain rate as process parameters and bearing length and fillet radius of the die as geometric features, different simulation runs are performed to investigate the effect of process and design features on the useful die life. Morrow’s stress life model shows a good correspondence between computed and actual failure of dies. By establishing correlations of die life with process and design parameters under different conditions, it was shown that the present investigation is a useful guideline at die design and extrusion process stages.
S. S. Akhtar A. F. M. Arif (&) Mechanical Engineering Department, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia e-mail: [email protected]
123
Keywords Fatigue analysis Extrusion die FE simulation Critical parameters
Introduction A very important factor contributing to the performance and economics (efficiency and quality) of any hot metalforming process is the service life of tooling. Product rework and rejects can be traced back to various defects spread over the die life cycle: die design, die manufacture, heat treatment, and die service. A number of mechanisms can cause initiation and propagation of die damage. Analysis of tool and die failure thus plays an important role in the prediction and prevention of die failure, and subsequently in improving process economics. In die fracturefailure, there are two common modes: one is overload fracture and the other is fatigue fracture. The large deformation load that exceeds the strength limit of the die in the forming processes can cause overload fracture, while, on the other hand, fatigue fracture is generally caused by the fact that the die works under severe loadin
Data Loading...
