ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Regular Article
Roles of Molybdenum and Tungsten on Reheat Cracking Susceptibility of 2.25Cr Heat Resistant Steels
Hyun Je SungNam Hoe HeoSung–Joon Kim
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2017 Volume 57 Issue 1 Pages 176-180


The rupture time of the tungsten-alloyed steel is much shorter than that of the molybdenum-alloyed steel. The fracture mode of the former steel is typically intergranular, but the latter steel shows a mixed fracture mode of intergranular and ductile. The shorter rupture time of the tungsten-alloyed steel is due to the active carbide formation reaction of tungsten in ferrite which depletes carbon within the matrix; the resulting higher segregation concentration of phosphorus at GCIs and carbide-free PAGBs. The longer rupture time of the other steel arises from two factors: the molybdenum segregated at the interfaces as a grain boundary strengthener; the repulsive segregation between carbon and phosphorus which repels phosphorus from the interfaces and produces the lower segregation concentration of phosphorus.

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© 2017 by The Iron and Steel Institute of Japan
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