A model for the development of microstructure in low-alloy steel (Fe-Mn-Si-C) weld deposits
H. K. D. H. Bhadeshia, L.-E. Svensson and B. Gretoft
University of Cambridge


Abstract

Experimentally observed microstructural variations in a series of low-alloy steel weld deposits containing different carbon concentrations (produced using experimental electrodes) are discussed in terms of a phenomenological model based on phase transformation theory. The model requires an input of austenite grain size, chemical composition and the cooling curve of the fusion zone; this allows the calculation of isothermal transformation diagrams and quantities necessary to define the start and finish temperatures of various reactions. Allotriomorphic ferrite growth is assumed to occur by a paraequilibrium transformation mechanism; its formation is found to determine the development of both Widmanstatten and acicular ferrite. It seems possible to rationalise the microstructural variations in terms of phase transformation theory, and although the presence of inclusions for the heterogeneous intragranular nucleation of acicular ferrite seems necessary, the inclusions, when present in a concentration beyond a limiting value, do not seem to control the overall development of microstructure.

Acta Metallurgica, Vol. 33, 1985, pp. 1271-1283.

The computer programs associated with this paper can be obtained from the Materials Algorithms Project





JNL

Science and Technology of Welding and Joining

A journal founded and edited by
S. A. David, T. Debroy and H.K.D.H. Bhadeshia
Published by The Institute of Materials, London, since 1996

MMWP1

Mathematical Modelling of Weld Phenomena

Eds. H. Cerjak and K. E. Eastering
Institute of Materials, London, 1993

MMWP2

Mathematical Modelling of Weld Phenomena 2

Edited by H. Cerjak
Series Editor H.K.D.H. Bhadeshia
Institute of Materials, London, 1995

MMWP3

Mathematical Modelling of Weld Phenomena 3

Edited by H. Cerjack
Series Editor H.K.D.H. Bhadeshia
Institute of Materials, London, 1997

mmpw4

Mathematical Modelling of Weld Phenomena 4

Edited by H. Cerjack
Series Editor H.K.D.H. Bhadeshia
Institute of Materials, London, 1998