Weldability of nitrogen-enhanced HSLA steels

Book · Fri Dec 31 04:00:00 EST 1993

OSTI ID:33206

Liao, F C; Liu, S; Olson, D L ^[1]

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1. Colorado School of Mines, Golden, CO (United States). Center for Welding and Joining Research

Light microscopy, electron microscopy and Charpy-V-Notch (CVN) testing were used to characterize two Ti-V microalloyed steels which contained 130 and 30 ppm of nitrogen with respect to weldability. Particular emphasis has been placed on the understanding of the heat input-microstructure-toughness relationship in the high nitrogen HSLA steel. Within the 1 to 3 kJ/mm heat input range, the high nitrogen steel exhibited coarse grained heat affected zone (CGHAZ) toughness superior to that of the low nitrogen steel. The transition temperatures (measured at 50 ft-lb impact energy) were, in average, 15 to 60 C lower than those presented by the low nitrogen steel. Quantitative metallography results showed that high nitrogen steel CGHAZs have smaller austenite grain size and larger amount of grain boundary ferrite. Combining the microstructural information and toughness data, it was concluded that for the high nitrogen steel to exhibit superior properties than the low nitrogen steel, the final HAZ microstructure must contain at least 60% of lathy (bainitic) phases, balanced with ferritic products.

• OSTI ID: 33206
• Report Number(s): CONF-930641--; ISBN 0-7918-0785-1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHARPY TEST
CHEMICAL COMPOSITION
EXPERIMENTAL DATA
FRACTURE PROPERTIES
HEAT AFFECTED ZONE
LOW ALLOY STEELS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NITROGEN ADDITIONS
PRECIPITATION
SIMULATION
WELDABILITY