25-27 April 2022
Conventum Conference Center
Europe/Vienna timezone

Plasma nitriding of H13 tool steel surfaces for improved thermal fatigue resistance of die-casting molds

27 Apr 2022, 11:40
20m
Room 2

Room 2

Oral Presentation Heat treatment Heat Treatment

Speaker

Guilherme Valadão (UEPG)

Description

The die-casting molds employed with molten aluminum under high pressures are subjected to severe localized corrosion, which is due, mainly, to the intense thermal cycling at temperatures around 700 °C. The recovery of molds usually involve the removal of the damaged region and reconstruction through welding. By a different approach, the resistance and lifespan of the recovered piece can be improved with multiple surface treatments to assure tribo-mechanical corrosion and thermal fatigue strengths. One of them is the surface nitriding, which promotes load bearing capacity to subsequent deposited films. The tool steel H13, presenting the lath martensite structure, was plasma nitrided at temperatures from 400 °C to 560 °C, providing hardened cases ( up to 12 GPa) with 100-220 μm thick. The modified surfaces consisted in graded layers, with a composite region on the top (mostly iron nitrides) and an underneath expanded nitrogen martensite. As an initial testing phase, 400 ºC nitrided surfaces received DLC coatings with ~120 μm thick. The wear coefficient reduced ~25 % for the nitrided surface as compared with the H13 steel that was only DLC coated. Thermal cycling tests in a homemade aluminum-bath apparatus, carried out under different amount of cycles with heating and cooling steps, disclosed the surface integrity was closely related with the nitrided surface structure.

Speaker Country Brazil

Primary authors

ANDERSON PUKASIEWICZ (UTFPR Ponta Grossa Campus) Gelson de Souza (State University of Ponta Grossa) Francisco Serbena (UEPG) Guilherme Valadão (UEPG) André Mayer (UTFPR Campus Ponta Grossa) Willian de Oliveira (UTFPR Campus Ponta Grossa)

Presentation Materials

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