Superplastic Behaviour of Rapidly Solidified Ultrahigh Carbon Alloy Tool Steel X380 CrVMo 25 93


Abstract:

This paper describes the superplastic properties of the rapidly solidified (RS) ultrahigh carbon alloy tool steel X380 CrVMo 25 93. By application of a specific production route, a microcrystalline structure can be produced which consists of a ferritic matrix (grain size d£3.8 µm) and fine dispersed carbides (d=1-3 µm). At test temperatures T of about 1050°C the tool steel can be deformed superplastically. Maximum tensile elongations are limited by cavity formation at the austenite/carbide interfaces. Compression tests reveal clearly that the cavity volume is decreased compared with that found in tensile tests. The mechanism for accommodation of grain boundary sliding is discussed in the light of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations. To demonstrate the potential of the tool steel X370 CrVMo 25 93 for the production of near net shape components some samples were precision forged in the superplastic regime.

Keywords:

ultrahigh carbon alloy tool steel, X380 CrVMo 25 9 3, vanadium carbides VC, tensile ductility, superplasticity, microcrystalline structure.


Author:

H. J. Speis and G. Frommeyer

Affiiation

Department of Materials Technologies, Max-Planck-Institut fur Eisenforschung GmbH, Dϋsseldorf, Germany


Source:

Materials Science and Technology, Vol. 7, August 1991, pp.718-722