Numerical die life estimation of a crack susceptible industrial hot forging process

Design, Characterisation and Numerical Investigations of Additively Manufactured H10 Hybrid-Forging Dies with Conformal Cooling Channels

“…In some areas, plastic deformations can occur, which can lead to material fatigue and finally to die failure due to cracks. For this reason, the FE method is increasingly used to determine the local stress values for the design of dies [19]. Optimised numerical die design can take into account the process variables that occur in the manufacturing process [20] and enable a more efficient design of the dies and step sequences.…”

“…This temperature was slightly reduced by a cooling time of five seconds, which depicts the transfer from the heating unit to the forming die. The thermomechanical properties of the used semi-finished product AISI 4140 (42CrMo4) were taken from a previous work described in [19] and modelled using the analytical approach by Hensel and Spittel. The preheated dies were set to a starting temperature of 180 • C.…”

Numerical Investigations on Stresses and Temperature Development of Tool Dies during Hot Forging

“…Within both investigations (stresses at different radii and temperature evolution over several cycles), the semi-finished product of material 1.7225 according to ISO 683-1 (also referred to as AISI 4140 or 42CrMo4) is used, which has already been characterised and parameterised for simulations within the scope of a previous work [3]. The tool steel 1.2367 according to ISO 4957-2 (also referred to as X38CrMoV5-3) is selected as a typical die material.…”

“…A press with a constant speed of 290.57 mm/s was set, resulting in a process time of 0.14 s. This corresponds to the abstracted construction of the press planned for later experimental trials. The friction was approximated with the combined friction model using a friction coefficient µ of 0.15, and a friction factor m of 0.3 based on the information of [16], and the experimental values obtained from previous tests [3]. The initial temperature distribution of the semi-finished product was determined by an additional cooling simulation, which depicts the transfer time of 5 seconds from the heating unit into the press.…”

“…By exceeding the local yield stress in the highly loaded areas, plastic deformations occurs, which leads to material fatigue and finally to tool failure due to cracks [2]. For this reason, the finite element method (FEM) is increasingly used to determine the local stress values for the design of tools [3]. Since the tools are subjected to thermo-mechanical alternating stress during their service life, which leads to elasticplastic failure, models for determining the tool life become more important [4].…”