Correlation of the microstructure and fracture toughness of the heat-affected zones of an SA 508 steel

Journal Article · Sat Apr 01 04:00:00 EST 2000 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-000-0106-2· OSTI ID:20050544

Kim, S; Kang, S Y; Oh, S J; Kwon, S J; Lee, S; Kim, J H; Hong, J H

In this study, microstructures of a heat-affected zone (HAZ) of an SA 508 steel were identified by Moessbauer spectroscopy in conjunction with microscopic observations, and were correlated with fracture toughness. Specimens with the peak temperature raised to 1350 C showed mostly martensite. With the peak temperature raised to 900 C, the martensite fraction was reduced, while bainite or martensite islands were formed because of the slow cooling from the lower austenite region and the increase in the prior austenite grain size. As the martensite fraction present inside the HAZ increased, hardness and strength tended to increase, whereas fracture toughness decreased. The microstructures were not changed much from the base metal because of the minor tempering effect when it was raised to 650 C or 700 C. However, fracture toughness of the subcritical HAZ with the peak temperature raised to 650 C to 700 C was seriously reduced after postweld heat treatment (PWHT) because carbide particles were of primary importance in initiating voids. Thus, the most important microstructural factors affecting fracture toughness were the martensite fraction before PWHT and the carbide fraction after PWHT.

• Research Organization: Pohang Univ. of Science and Technology (KR)
• OSTI ID: 20050544
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 4 Vol. 31; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AUSTENITE
BAINITE
CORRELATIONS
FRACTURE PROPERTIES
HEAT AFFECTED ZONE
MARTENSITE
MICROSTRUCTURE
STEEL-ASTM-A508
TEMPERATURE DEPENDENCE