TY - JOUR

T1 - The influence local cooling to heat checking and crack formation in HPDC die inserts

AU - Hofer-Hauser, Peter

AU - Gschwandtner, Reinhold

AU - Berbic, Mirnes

PY - 2024/12

Y1 - 2024/12

N2 - High-pressure die-casting tools are subject to various wear inducing phenomena in industrial production. Beside from erosive and abrasive wear due to high flow velocities of the melt phenomena caused by the direct contact of the cast alloy with the tool steel are present. On the one hand there are thermo-chemical effects due to the direct contact of the liquid metal and the surface leading to the dissolution of the steel by diffusive effects. This is also called die soldering. On the other hand, the cyclic character process leads to inhomogeneous temperature fields and rapid changes in temperatures especially at the tool surface. This leads to significant thermal stresses and thermo-mechanical fatigue. Defects such as heat checking, stress-cracks or spalling may occur during the tool’s life cycle. In this work the influence of different cooling methods on the thermo-mechanical loads in HPDC-die inserts was analyzed. A numerical study of the thermal and mechanical loads in spray cooled, permanently cooled and pulse cooled core inserts was done to evaluate the effects of these three approaches. In order to characterize the thermo-mechanical damage in tool inserts at conditions close to the real industrial process, experiments on a test rig were performed. The influences of the type of the tool steel, the fabrication method (conventional vs. additive manufacturing), the surface condition of the cooling channel and the heat treatment of the inserts were evaluated by means of optical microscopy and hardness measurement. The results of these tests are presented in this work. A clear difference in the wear behavior between the tested specimens could be obtained. Especially the pulse cooled specimens a significant drop of hardness could be observed which leads to the hypothesis that damage formation in HPDC-die inserts is not only related to absolute loads but also to the degradation of the material during the life cycle of the tool.

AB - High-pressure die-casting tools are subject to various wear inducing phenomena in industrial production. Beside from erosive and abrasive wear due to high flow velocities of the melt phenomena caused by the direct contact of the cast alloy with the tool steel are present. On the one hand there are thermo-chemical effects due to the direct contact of the liquid metal and the surface leading to the dissolution of the steel by diffusive effects. This is also called die soldering. On the other hand, the cyclic character process leads to inhomogeneous temperature fields and rapid changes in temperatures especially at the tool surface. This leads to significant thermal stresses and thermo-mechanical fatigue. Defects such as heat checking, stress-cracks or spalling may occur during the tool’s life cycle. In this work the influence of different cooling methods on the thermo-mechanical loads in HPDC-die inserts was analyzed. A numerical study of the thermal and mechanical loads in spray cooled, permanently cooled and pulse cooled core inserts was done to evaluate the effects of these three approaches. In order to characterize the thermo-mechanical damage in tool inserts at conditions close to the real industrial process, experiments on a test rig were performed. The influences of the type of the tool steel, the fabrication method (conventional vs. additive manufacturing), the surface condition of the cooling channel and the heat treatment of the inserts were evaluated by means of optical microscopy and hardness measurement. The results of these tests are presented in this work. A clear difference in the wear behavior between the tested specimens could be obtained. Especially the pulse cooled specimens a significant drop of hardness could be observed which leads to the hypothesis that damage formation in HPDC-die inserts is not only related to absolute loads but also to the degradation of the material during the life cycle of the tool.

KW - HPDC, Tooling, Thermomachanial Wear, Additive Manufacturing

M3 - Article

VL - 71

SP - 176

EP - 192

JO - Livarski vestnik

JF - Livarski vestnik

SN - 0024-5135

IS - 4

ER -