A New Opportunity for the Design of Advanced High Strength Steels
A New Opportunity for the Design of Advanced High Strength Steels
07/03/2017
A New Opportunity for the Design of Advanced High Strength Steels with Heterogeneous-Phase Microstructures via Rapid Thermal Processing. Journal of Nanoscience with Advanced Technology (2017) Vol. 2(1), pp. 20-23.
S. Papaefthymiou
Abstract
In the following paper, the developments in Advanced High Strength Steels (AHSS) that are
used in automotive industry are summarized. AHSS show good formability while maintaining
high strength values. These properties can be achieved via grain refining, mixed ferritic
microstructures and by leveraging phenomena such as Transformation Induced Plasticity
and Twinning Induced Plasticity (TWIP). However, time and energy consuming thermal
processes as well as expensive alloying additions should be employed in order to achieve
these properties. The new era of AHSS requires combinations of greater strength – ductility
via ultra-grain – refined ferrite, martensite, bainite and austenite at a cost significantly less
than the previous grades. It is envisaged that microstructural evolution under the effect of
ultra-fast heating and the subsequent quenching or air cooling may result to a new outlook
for alloy design. The key aspect in this technological possibility is the effect of chemical
heterogeneity in the initial microstructure. The inhomogeneous microstructure remains
unchanged due to the rapid reheating as a result of the restriction of the time available for
solid state diffusion. A promising example of such technology is the single-stepped reheating
of steel which, although unconventional, has been observed to lead to complex
microstructures of chemical heterogeneity.