Characterization of Steel Thixoforming Tool Materials by High Temperature Compression Tests

Abstract

The experimental set-up and the results of high temperature compression tests for the characterization of tool materials for steel thixoforming are presented. The scope of this test is to reproduce the load profile of steel thixoforming processes consisting of mechanical, thermal, tribological, and chemical components on the forming mould. Tool materials were chosen following a concept within the Collaborative Research Center -SFB 289 -"Forming of metals in the semi-solid state and their properties". Three materials groups are distinguished: thin film deposited by physical vapor deposition (PVD) and plasma assisted chemical vapour deposition (PACVD), thick coatings (thermal spraying), and bulk ceramic materials. Samples were characterized using scanning electron microscopy (SEM), electron-dispersive spectroscopy (EDS) and X-Ray diffraction analysis (XRD). The results show varying resistance of the tool materials concerning the load profile. In order to provide an appropriate tool solution for the thixoforming of steels, different load profiles within the forming moulds are identified and the corresponding tool part is made from that material with the best performance.

Impact of experimental conditions on material response during forming of steel in semi-solid state

“…It was found around 1437 • C when using the "cold" die and the 40 mm/s ram speed. Kopp et al (2004) and Li et al (2005) presented the same kind of results obtained for other steel grades. Carrying out compression tests on aluminium alloys, Kang et al (1999) also found similar results.…”

A review on steel thixoforming

“…In the SFB289 project [56], three types of materials have been compared: thin film PVD and PACVD; thermally sprayed thick coatings and bulk ceramic materials. The results showed that the behaviour was sensitive to the stresses at the surface of the die and therefore the die should be made of different materials in different positions.…”

Thermal cycling of AlTiN- and AlTiON-coated hot work tool steels at elevated temperatures

“…The performance of PVD oxide coatings, nevertheless, deserves attention. TiAlN/␥-Al 2 O 3 and TiAlN/t-ZrO 2 PVD coated plates had not shown any visible signs of coating failure or rupture at the surface [23,51,52].…”