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Title: The Stress-Relief Cracking Susceptibility of a New Ferritic Steel - Part I: Single-Pass Heat-Affected Zone Simulations

Abstract

The stress-relief cracking susceptibility of single-pass welds in a new ferritic steel, HCM2S, has been evaluated and compared to 2.25Cr-1Mo steel using Gleeble techniques. Simulated coarse-grained heat-affected zones (CGHAZ) were produced under a range of energy inputs and tested at various post-weld heat treatment (PWHT) temperatures. Both alloys were tested at a stress of 325 MPa. The 2.25 Cr-1Mo steel was also tested at 270 MPa to normalize for the difference in yield strength between the two materials. Light optical and scanning electron microscopy were used to characterize the CGHAZ microstructure. The ''as-welded'' CGHAZ of each alloy consisted of lath martensite or bainite and had approximately equal prior austenite grain sizes. The as-welded hardness of the 2.25Cr-1Mo steel CGHAZ was significantly higher than that of the HCM2S alloy. Over the range studied energy input had no effect on the as-welded microstructure or hardness of either alloy. The energy input also had no effect on the stress-relief cracking susceptibility of either material. Both alloys failed intergranularly along prior austenite grain boundaries under all test conditions. The 2.25Cr-1Mo steel samples experienced significant macroductility and some microductility when tested at 325 MPa. The ductility decreased significantly when tested at 270 MPa but wasmore » still higher that than of HCM2S at each test condition. The time to failure decreased with increasing PWHT Temperature for each material. There was no significant difference in the times to failure between the two materials. Varying energy input and stress had no effect on the time-to failure. The ductility, as measured by reduction in are% increased with increasing PWHT temperature for 2.25 Cr-1Mo steel tested at both stresses. However, PWHT temperature had no effect on the ductility of HCM2S. The hardness of the CGHAZ for 2.25Cr-1Mo steel decreased significantly after PWHT, but remained constant for HCM2S. The differences in stress-relief cracking response are discussed in terms of the differences in composition and expected carbide precipitation sequence for each alloy during PWHT.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
15185
Report Number(s):
SAND99-3168J
TRN: US200221%%436
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article
Journal Name:
Welding Journal Research Suppliment
Additional Journal Information:
Other Information: Submitted to Welding Journal Research Supplement; PBD: 15 Dec 1999
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; FERRITIC STEELS; GRAIN BOUNDARIES; GRAIN SIZE; HEAT AFFECTED ZONE; HEAT TREATMENTS; SCANNING ELECTRON MICROSCOPY; STEELS; YIELD STRENGTH

Citation Formats

NAWROCKI, J G, DUPONT, J N, ROBINO, CHARLES V, and MARDER, A R. The Stress-Relief Cracking Susceptibility of a New Ferritic Steel - Part I: Single-Pass Heat-Affected Zone Simulations. United States: N. p., 1999. Web.
NAWROCKI, J G, DUPONT, J N, ROBINO, CHARLES V, & MARDER, A R. The Stress-Relief Cracking Susceptibility of a New Ferritic Steel - Part I: Single-Pass Heat-Affected Zone Simulations. United States.
NAWROCKI, J G, DUPONT, J N, ROBINO, CHARLES V, and MARDER, A R. 1999. "The Stress-Relief Cracking Susceptibility of a New Ferritic Steel - Part I: Single-Pass Heat-Affected Zone Simulations". United States. https://www.osti.gov/servlets/purl/15185.
@article{osti_15185,
title = {The Stress-Relief Cracking Susceptibility of a New Ferritic Steel - Part I: Single-Pass Heat-Affected Zone Simulations},
author = {NAWROCKI, J G and DUPONT, J N and ROBINO, CHARLES V and MARDER, A R},
abstractNote = {The stress-relief cracking susceptibility of single-pass welds in a new ferritic steel, HCM2S, has been evaluated and compared to 2.25Cr-1Mo steel using Gleeble techniques. Simulated coarse-grained heat-affected zones (CGHAZ) were produced under a range of energy inputs and tested at various post-weld heat treatment (PWHT) temperatures. Both alloys were tested at a stress of 325 MPa. The 2.25 Cr-1Mo steel was also tested at 270 MPa to normalize for the difference in yield strength between the two materials. Light optical and scanning electron microscopy were used to characterize the CGHAZ microstructure. The ''as-welded'' CGHAZ of each alloy consisted of lath martensite or bainite and had approximately equal prior austenite grain sizes. The as-welded hardness of the 2.25Cr-1Mo steel CGHAZ was significantly higher than that of the HCM2S alloy. Over the range studied energy input had no effect on the as-welded microstructure or hardness of either alloy. The energy input also had no effect on the stress-relief cracking susceptibility of either material. Both alloys failed intergranularly along prior austenite grain boundaries under all test conditions. The 2.25Cr-1Mo steel samples experienced significant macroductility and some microductility when tested at 325 MPa. The ductility decreased significantly when tested at 270 MPa but was still higher that than of HCM2S at each test condition. The time to failure decreased with increasing PWHT Temperature for each material. There was no significant difference in the times to failure between the two materials. Varying energy input and stress had no effect on the time-to failure. The ductility, as measured by reduction in are% increased with increasing PWHT temperature for 2.25 Cr-1Mo steel tested at both stresses. However, PWHT temperature had no effect on the ductility of HCM2S. The hardness of the CGHAZ for 2.25Cr-1Mo steel decreased significantly after PWHT, but remained constant for HCM2S. The differences in stress-relief cracking response are discussed in terms of the differences in composition and expected carbide precipitation sequence for each alloy during PWHT.},
doi = {},
url = {https://www.osti.gov/biblio/15185}, journal = {Welding Journal Research Suppliment},
number = ,
volume = ,
place = {United States},
year = {Wed Dec 15 00:00:00 EST 1999},
month = {Wed Dec 15 00:00:00 EST 1999}
}