S13  Integridade Estrutural    Titulo: DETERMINATION OF THE CLEAVAGE STRESS OF FERRITIC STEELS IN THE DBT REGION USING SEM AND FRAMTIC MODEL   Resumo : ABSTRACT. THE PURPOSE OF THIS WORK IS TO PRESENT A NEW APPROACH BASED ON FRACTOGRAPHICAL OBSERVATIONS, ACCOMPLISHED WITH SCAN ELECTRONIC MICROSCOPY, DEVELOPED FOR OBTAINING THE NECESSARY LEVEL OF STRESS NECESSARY TO CAUSE CLEAVAGE FRACTURE IN FERRITIC STEELS IN THE DUCTILE-TO-BRITTLE TRANSITION (DBT) REGION. THIS APPROACH USES A MODEL, NAMED FRAMTIC, BASED ON ANALYTICAL AND EXPERIMENTAL PROCEDURES AND APPLICABLE TO FERRITIC STEELS, THAT WAS INITIALLY CONCEIVED FOR MAKING POSSIBLE A BETTER UNDERSTANDING OF THE FRACTURE TOUGHNESS BEHAVIOR IN THE DUCTILE-TO-BRITTLE TRANSITION. THE MODEL USES A NUMERICAL CHARACTERIZATION OF THE CRACK TIP STRESS FIELD MODIFIED BY THE J-Q CONSTRAINT THEORY AND A WEAK LINK ASSUMPTION TO PREDICT BEHAVIOR IN THE TRANSITION. THE MODEL IS ABLE TO PREDICT THE FRACTURE TOUGHNESS SCATTERBAND FOR ANY DEFINED GEOMETRY FROM THE KNOWLEDGE OF A TOUGHNESS SCATTERBAND MEASURED ON TEST SPECIMEN GEOMETRY AND CAN DETERMINE THE END OF THE TRANSITION REGION. A NEW APPLICATION OF THE MODEL IS APPLIED, TOGETHER WITH FRACTOGRAPHICAL OBSERVATIONS OF FRACTURE SURFACES, IS HERE PRESENTED: THE COMPUTATION AND/OR ASSESSMENT OF THE LEVEL OF STRESS RELATED TO THE CLEAVAGE FRACTURE INITIATION, NAMELY CLEAVAGE STRESS. KEYWORDS: FRACTURE MECHANICS, DUCTILE-TO-BRITTLE TRANSITION, CLEAVAGE, FERRITICSTEELS, FRACTOGRAPHIES     Autores : Andrade, Arnaldo H.P. DeAquino, Carlos Tasso Eira Ferreira, Itamar 0 Landes, John D.     Trabalho Completo :   COBEM99 | Comissão  Organizadora | Palestras | Sessões Técnicas | Autor | Simpósios e Sessões Especiais | Revisores |  Título  dos  Trabalhos | Local