Solidification and solid state transformations of austenitic stainless steel welds

Technical Report · Sat May 01 00:00:00 EDT 1982

DOI:https://doi.org/10.2172/5106928· OSTI ID:5106928

Brooks, J A; Williams, J C; Thompson, A W

The microstructure of austenitic stainless steel welds can contain a large variety of ferrite morphologies. It was originally thought that many of these morphologies were direct products of solidification. Subsequently, detailed work on castings suggested the structures can solidify either as ferrite or austenite. However, when solidification occurs by ferrite, a large fraction of the ferrite transforms to austenite during cooling via a diffusion controlled transformation. It was also shown by Arata et al that welds in a 304L alloy solidified 70-80% as primary ferrite, a large fraction of which also transformed to austenite upon cooling. More recently it was suggested that the cooling rates in welds were sufficiently high that diffusionless transformations were responsible for several commonly observed ferrite morphologies. However, other workers have suggested that even in welds, delta ..-->.. ..gamma.. transformations are diffusion controlled. A variety of ferrite morphologies have more recently been characterized by Moisio and coworkers and by David. The purpose of this paper is to provide further understanding of the evaluation of the various weld microstructures which are related to both the solidification behavior and the subsequent solid state transformations. To accomplish this, both TEM and STEM (Scanning Transmission Electron Microscopy) techniques were employed.

• Research Organization: Sandia National Lab. (SNL-CA), Livermore, CA (United States); Carnegie Mellon Univ., Pittsburgh, PA (United States)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5106928
• Report Number(s): SAND-82-8703; ON: DE82015081
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AUSTENITE
SOLIDIFICATION
AUSTENITIC STEELS
MICROSTRUCTURE
PHASE STUDIES
FERRITE
SCANNING ELECTRON MICROSCOPY
TRANSMISSION ELECTRON MICROSCOPY
WELDED JOINTS
ALLOYS
CARBON ADDITIONS
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
MICROSCOPY
PHASE TRANSFORMATIONS
STEELS
360102* - Metals & Alloys- Structure & Phase Studies