Paper Information

Journal:   AMIRKABIR   SPRING 2003 , Volume 14 , Number 54-B; Page(s) 488 To 489.
 
Paper: 

FRACTURE TOUGHNESS OF DUCTILE CAST IRAN USING J-INTEGRAL

 
 
Author(s):  KAZAZI G., BOUTORABI S.M.A.
 
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Abstract: 

The effects of carbon equivalents of 2.3, 3.3 and 4.3% on the microstructure, hardness and fracture toughness of a low alloyed ductile cast iron in as cast, annealed, normalized and austempered conditions have been investigated. Fracture toughness was measured using a plain-strain fracture toughness (kIc) test and also J-Integral approach. The results show that the pearlite content increases as the CE decreases from 4.3 to 2.3% The nodularity and nodule count also decrease with decreasing the CE%. The annealed samples show a predominantly ferritic structure. Iron with 2.3 CE% shows pearlitic microstructure. The austempered microstructure contains bainitic ferrite and retained austenite at all carbon equivalents. The fracture toughness value (kQ and kIc) of ductile iron increases with increasing the CE% in all conditions and a maximum value is obtained in austempered condition. The hardness decreases with increasing CE% and an maximum value of 526 HV50 can be obtained at 2.3 CE% in a austempered condition. The SEM study shows that all the fractures of austempered specimens are ductile in nature whilst all that of normalized condition are brittle. Fracture behavior of 4.3 CE% ductile iron in as cast and annealed conditions are ductile where those of 2.3% are brittle. The iron with 3.3% shows a brittle fracture in as cast condition and a ductile fracture in annealed condition. The results show that J. integral approach can be used in measuring of kIc, particulary if the kIc values can not be achieved.

 
Keyword(s): FRACTURE TOUGHNESS, MICROSTRUCTURE, CARBON EQUIVALENT PLAIN-STRAIN
 
References: 
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