Microstructural investigations of XW-42 and M2 tool steels in semi-solid zones via direct partial remelting route
- 212 Downloads
A suitable microstructure for thixoforming consists of spheroidal grains in a liquid matrix. In order to achieve this, some processing routes have been established. In this study, microstructural evolution of XW-42 and AISI M2 steels via direct partial remelting from the as-annealed condition was examined. Both steels were found to possess certain types of carbides that dissolved when subjected to heating inside the semi-solid zones. The types of carbides were MC-M6C for AISI M2 steel (fully dissolved between 1280 and 1300 °C) and M7C3 for XW-42 steel (fully dissolved between 1250 and 1270 °C). The dissolution of these grain boundary carbides during partial remelting helps with the grain spheroidisation and also with providing grain lubrication for the forming process through solid–liquid particle contact. In addition, solid–solid contacts were also observed (in 2D as well as 3D microstructural observation) and considered useful to provide structural integrity prior to forming. However, these contacts also must also be weak enough to be sheared easily. Compression test results for AISI M2 steel showed that thixotropic behaviour and complete mould filling were observed starting from 35 liquid percent. The same behaviour is also expected to occur for XW-42 steel due to its similarity in microstructural evolution with AISI M2 steel.
KeywordsCarbide Differential Thermal Analysis Solid Skeleton Eutectic Carbide Inductive Couple Plasma Mass Spectroscopy
The authors would like to thank to the Ministry of Science, Technology and Innovation (MOSTI) Malaysia for sponsoring this study and P. Kapranos of The University of Sheffield for helpful discussions.
- 1.Kapranos P, Kirkwood DH, Sellars CM (1989) In : Exner HE Schumacher V (eds) Advanced material and process, vol 1: advanced processing and high temperature materials. Proceedings EUROMAT Conference, Deutsche Gesellschaft für Metallkunde, OberuselGoogle Scholar
- 4.Hirt G, Khizhnyakova L, Baadjou R, Knauf F, Kopp R (2009) In: Hirt G, Kopp R (eds) Thixoforming-semi-solid metal processing. Wiley-VCH Verlag GmbH, WeinheimGoogle Scholar
- 21.Roberts GA, Hamaker JC, Johnson AR (1971) Tool steels, 2nd edn. American Society for Metals, Metals ParkGoogle Scholar
- 22.ASM (1998) Metals handbook, 9th edn, vol 1. ASM International, Metals ParkGoogle Scholar
- 26.Bhadeshia HKDH, Honeycombe RWK (2006) Steels-microstructures and properties, 3rd edn. Butterworth-Heinemann, OxfordGoogle Scholar
- 29.Omar MZ, Palmiere EJ, Howe AA, Atkinson HV, Kapranos P (2004) In: Proceeding of the 8th international conference on semi-solid processings of alloys and composites, Limassol. North American Die Casting Association, WheelingGoogle Scholar