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Title: Mechanisms of hydrogen-assisted fracture in austenitic stainless steel welds.

Abstract

The objective of this study was to quantify the hydrogen-assisted fracture susceptibility of gas-tungsten arc (GTA) welds in the nitrogen-strengthened, austenitic stainless steels 21Cr-6Ni-9Mn (21-6-9) and 22Cr-13Ni-5Mn (22-13-5). In addition, mechanisms of hydrogen-assisted fracture in the welds were identified using electron microscopy and finite-element modeling. Elastic-plastic fracture mechanics experiments were conducted on hydrogen-charged GTA welds at 25 C. Results showed that hydrogen dramatically lowered the fracture toughness from 412 kJ/m{sup 2} to 57 kJ/m{sup 2} in 21-6-9 welds and from 91 kJ/m{sup 2} to 26 kJ/m{sup 2} in 22-13-5 welds. Microscopy results suggested that hydrogen served two roles in the fracture of welds: it promoted the nucleation of microcracks along the dendritic structure and accelerated the link-up of microcracks by facilitating localized deformation. A continuum finite-element model was formulated to test the notion that hydrogen could facilitate localized deformation in the ligament between microcracks. On the assumption that hydrogen decreased local flow stress in accordance with the hydrogen-enhanced dislocation mobility argument, the finite-element results showed that deformation was localized in a narrow band between two parallel, overlapping microcracks. In contrast, in the absence of hydrogen, the finite-element results showed that deformation between microcracks was more uniformly distributed.

Authors:
;  [1]; ;  [1]
  1. (University of Illinois, Urbana, IL)
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
944382
Report Number(s):
SAND2005-1816C
TRN: US200902%%737
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: Proposed for presentation at the 11th International Conference on Fracture held March 23, 2005 in Turin, Italy.
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; 36 MATERIALS SCIENCE; DEFORMATION; DISLOCATIONS; ELECTRON MICROSCOPY; FLOW STRESS; FRACTURE MECHANICS; FRACTURE PROPERTIES; FRACTURES; HYDROGEN; LIGAMENTS; MICROSCOPY; NUCLEATION; SIMULATION; STAINLESS STEELS

Citation Formats

Balch, Dorian K., Sofronis, Petros, Somerday, Brian P., and Novak, Paul. Mechanisms of hydrogen-assisted fracture in austenitic stainless steel welds.. United States: N. p., 2005. Web.
Balch, Dorian K., Sofronis, Petros, Somerday, Brian P., & Novak, Paul. Mechanisms of hydrogen-assisted fracture in austenitic stainless steel welds.. United States.
Balch, Dorian K., Sofronis, Petros, Somerday, Brian P., and Novak, Paul. Tue . "Mechanisms of hydrogen-assisted fracture in austenitic stainless steel welds.". United States.
@article{osti_944382,
title = {Mechanisms of hydrogen-assisted fracture in austenitic stainless steel welds.},
author = {Balch, Dorian K. and Sofronis, Petros and Somerday, Brian P. and Novak, Paul},
abstractNote = {The objective of this study was to quantify the hydrogen-assisted fracture susceptibility of gas-tungsten arc (GTA) welds in the nitrogen-strengthened, austenitic stainless steels 21Cr-6Ni-9Mn (21-6-9) and 22Cr-13Ni-5Mn (22-13-5). In addition, mechanisms of hydrogen-assisted fracture in the welds were identified using electron microscopy and finite-element modeling. Elastic-plastic fracture mechanics experiments were conducted on hydrogen-charged GTA welds at 25 C. Results showed that hydrogen dramatically lowered the fracture toughness from 412 kJ/m{sup 2} to 57 kJ/m{sup 2} in 21-6-9 welds and from 91 kJ/m{sup 2} to 26 kJ/m{sup 2} in 22-13-5 welds. Microscopy results suggested that hydrogen served two roles in the fracture of welds: it promoted the nucleation of microcracks along the dendritic structure and accelerated the link-up of microcracks by facilitating localized deformation. A continuum finite-element model was formulated to test the notion that hydrogen could facilitate localized deformation in the ligament between microcracks. On the assumption that hydrogen decreased local flow stress in accordance with the hydrogen-enhanced dislocation mobility argument, the finite-element results showed that deformation was localized in a narrow band between two parallel, overlapping microcracks. In contrast, in the absence of hydrogen, the finite-element results showed that deformation between microcracks was more uniformly distributed.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2005},
month = {3}
}

Conference:
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