TY - JOUR
T1 - Low-Temperature aging characteristics of type 316L stainless steel welds
T2 - Dependence on solidification mode
AU - Abe, Hiroshi
AU - Watanabe, Yutaka
N1 - Funding Information:
This work was performed as a part of the ‘‘SCC mechanism studies of L-grade stainless steels in high-temperature water’’ organized by JSCE and supported by Japanese BWR utilities. This work was supported by a grant-in-aid for JSPS fellowship (Grant No. 19008176). Help by Dr. Miyazaki, Department of Instrumental Analysis, Technical Division, School of Engineering, Tohoku University, for the TEM observation is greatly appreciated.
PY - 2008/6
Y1 - 2008/6
N2 - Thermal aging embrittlement of light water reactor (LWR) components made of stainless steel cast has been recognized as a potential degradation issue, and careful attention has been paid to it. Although welds of austenitic stainless steels have γδ duplex microstructure, which is similar to that of the stainless steel cast, examination of the thermal aging characteristics of the stainless steel welds is very limited. In this investigation, two types of type 316L stainless steel weld metal with different solidification modes were prepared using two kinds of filler metals having tailored Ni equivalent and Cr equivalent. Differences between the two weld metals in the morphology of microstructure, in the composition of δ -ferrite, and in hardening behaviors with isothermal aging at 335 °C have been investigated. The hardness of the ferrite phase has increased with aging time, while the hardness of austenite phase has stayed the same. The mottled aspect has been observed in δ -ferrite of aged samples by transmission electron microscopy (TEM) observation. These characteristics suggest that spinodal decomposition has occurred in δ -ferrite by aging at 335 °C. The age-hardening rate of δ -ferrite was faster for the primary austenite solidification mode (AF mode) sample than the primary ferrite solidification mode (FA mode) sample in the initial stage of the aging up to 2000 hours. It has been suggested that the solidification mode can affect the kinetics of spinodal decomposition.
AB - Thermal aging embrittlement of light water reactor (LWR) components made of stainless steel cast has been recognized as a potential degradation issue, and careful attention has been paid to it. Although welds of austenitic stainless steels have γδ duplex microstructure, which is similar to that of the stainless steel cast, examination of the thermal aging characteristics of the stainless steel welds is very limited. In this investigation, two types of type 316L stainless steel weld metal with different solidification modes were prepared using two kinds of filler metals having tailored Ni equivalent and Cr equivalent. Differences between the two weld metals in the morphology of microstructure, in the composition of δ -ferrite, and in hardening behaviors with isothermal aging at 335 °C have been investigated. The hardness of the ferrite phase has increased with aging time, while the hardness of austenite phase has stayed the same. The mottled aspect has been observed in δ -ferrite of aged samples by transmission electron microscopy (TEM) observation. These characteristics suggest that spinodal decomposition has occurred in δ -ferrite by aging at 335 °C. The age-hardening rate of δ -ferrite was faster for the primary austenite solidification mode (AF mode) sample than the primary ferrite solidification mode (FA mode) sample in the initial stage of the aging up to 2000 hours. It has been suggested that the solidification mode can affect the kinetics of spinodal decomposition.
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U2 - 10.1007/s11661-008-9511-8
DO - 10.1007/s11661-008-9511-8
M3 - Article
AN - SCOPUS:43149117908
VL - 39 A
SP - 1392
EP - 1398
JO - Metallurgical Transactions A (Physical Metallurgy and Materials Science)
JF - Metallurgical Transactions A (Physical Metallurgy and Materials Science)
SN - 1073-5623
IS - 6
ER -