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Title: Controlling Metastable Phase Transformations in Stainless Steel Laser Welds.


Abstract not provided.

; ; ; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: Proposed for presentation at the Joining IMOG held March 6-7, 2007 in Los Alamos, NM.
Country of Publication:
United States

Citation Formats

Perricone, Matthew Joseph., Robino, Charles V, Reece, Mark, Duran, Peter S., and MacCallum, Danny O'Neill. Controlling Metastable Phase Transformations in Stainless Steel Laser Welds.. United States: N. p., 2007. Web.
Perricone, Matthew Joseph., Robino, Charles V, Reece, Mark, Duran, Peter S., & MacCallum, Danny O'Neill. Controlling Metastable Phase Transformations in Stainless Steel Laser Welds.. United States.
Perricone, Matthew Joseph., Robino, Charles V, Reece, Mark, Duran, Peter S., and MacCallum, Danny O'Neill. Thu . "Controlling Metastable Phase Transformations in Stainless Steel Laser Welds.". United States. doi:.
title = {Controlling Metastable Phase Transformations in Stainless Steel Laser Welds.},
author = {Perricone, Matthew Joseph. and Robino, Charles V and Reece, Mark and Duran, Peter S. and MacCallum, Danny O'Neill},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Mar 01 00:00:00 EST 2007},
month = {Thu Mar 01 00:00:00 EST 2007}

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  • Spatially resolved x-ray diffraction (SRXRD) and time resolved x-ray diffraction (TRXRD) were used to investigate real time solid state phase transformations and solidification in AISI type 304 stainless steel gas tungsten arc (GTA) welds. These experiments were conducted at Stanford Synchrotron Radiation Laboratory (SSRL) using a high flux beam line. Spatially resolved observations of {gamma} {leftrightarrow} {delta} solid state phase transformations were performed in the heat affected zone (HAZ) of moving welds and time-resolved observations of the solidification sequence were performed in the fusion zone (FZ) of stationary welds after the arc had been terminated. Results of the moving weldmore » experiments showed that the kinetics of the {gamma}{yields}{delta} phase transformation on heating in the HAZ were sufficiently rapid to transform a narrow region surrounding the liquid weld pool to the {delta} ferrite phase. Results of the stationary weld experiments showed, for the first time, that solidification can occur directly to the {delta} ferrite phase, which persisted as a single phase for 0.5s. Upon solidification to {delta}, the {delta} {yields} {gamma} phase transformation followed and completed in 0.2s as the weld cooled further to room temperature.« less
  • Spatially Resolved X-Ray Diffraction (SRXRD) has been used to identify a previously unobserved low temperature ferrite ({delta})/austenite({gamma}) phase transformation in the heat affected zone (HAZ) of 2205 Duplex Stainless Steel (DSS) welds. In this ''ferrite dip'' transformation, the ferrite transforms to austenite during heating to peak temperatures on the order of 750 C, and re-transforms to ferrite during cooling, resulting in a ferrite volume fraction equivalent to that in the base metal. Time Resolved X-Ray Diffraction (TRXRD) and laser dilatometry measurements during Gleeble{reg_sign} thermal simulations are performed in order to verify the existence of this low temperature phase transformation. Thermodynamicmore » and kinetic models for phase transformations, including both local-equilibrium and para-equilibrium diffusion controlled growth, show that diffusion of substitutional alloying elements does not provide a reasonable explanation for the experimental observations. On the other hand, the diffusion of interstitial alloying elements may be rapid enough to explain this behavior. Based on both the experimental and modeling results, two mechanisms for the ''ferrite dip'' transformation, including the formation and decomposition of secondary austenite and an athermal martensitic-type transformation of ferrite to austenite, are considered.« less
  • Microstructure development in low alloy steel welds depends on various phase transformations that are a function of weld heating and cooling. The phase changes include non-metallic oxide inclusion formation in the liquid state, weld pool solidification, and solid state transformations. In this paper the mechanism of inclusion formation during low alloy steel welding is considered and the model predictions are compared with published results. The effect of inclusions on the austenite to ferrite transformation kinetics is measured and the mechanisms of transformation are discussed. The austenite gain development is related to the driving force for transformation of {delta} ferrite tomore » austenite.« less
  • Neutron strain scanning has proven very effective in non-destructive mapping of the distribution of residual stresses in weldments. Strain scanning of Gleeble test bars of 2 1/4 Cr-1 Mo steel has been carried out in conjunction with strain scanning investigations of a multipass weld in 0.5-in. plate of the same alloy. The residual stresses in the Cleeble bars depend on the time spent at the maximum temperature and the rate of cooling. The longitudinal strains on the Gleeble bar center-line are tensile with a maximum on either side of the central hot zone. The transverse strains are compressive but varymore » with thermal treatment to a higher degree than variations in the longitudinal strains. The difference between strains at the center-line and off the center-line can be significantly greater than statistical error in aircooled Gleeble bars. The strains in the Gleeble bar have a high tensile component parallel to the direction of maximum heat transfer (viz. along the bar axis). By contrast, the large tensile strains in the heat-affected zone (HAZ) of the weldment are along the weld line which is essentially perpendicular to the direction of maximum heat transfer. The simulated conditions present in Gleeble bar test specimens are different from that observed in weld HAZ.« less