MICROSTRUCTURAL EVOLUTION DURING SOLIDIFICATION OF AUSTENITIC STAINLESS-STEEL WELD METALS - A COLOR METALLOGRAPHIC AND ELECTRON-MICROPROBE ANALYSIS STUDY
K. Rajasekhar et al., MICROSTRUCTURAL EVOLUTION DURING SOLIDIFICATION OF AUSTENITIC STAINLESS-STEEL WELD METALS - A COLOR METALLOGRAPHIC AND ELECTRON-MICROPROBE ANALYSIS STUDY, Materials characterization, 38(2), 1997, pp. 53-65
Structural evolution during solidification of austenitic stainless ste
el welds plays a crucial role in solidification cracking and microsegr
egation. Currently, there is no unambiguous method available to study
the solidification mechanism in detail. The present investigation was
undertaken to explore the potential of color metallography for reveali
ng solidification structures. Weld composition was altered by adding v
arying amounts of nitrogen such that its location with respect to the
phase diagram is moved in a specified direction. The controlled variat
ions in the solidification mechanism thus brought about were studied m
etallographically, using Beraha's etchant and electron microprobe anal
ysis. Metallographic studies complemented by electron probe microanaly
sis demonstrated color metallography to be a highly useful, simple, an
d reliable technique for revealing solidification structures. Color et
ching enables the quantitative estimation of high-temperature phases i
n the ferritic-austenitic mode of solidification. It also reveals the
three-phase reaction mechanism in the (L + delta + gamma) region in de
tail. Ln fully austenitic structures, color etching reveals the growth
patterns of cell structures and the effective interface area where im
purities are expected to segregate. (C) Elsevier Science Inc., 1997.