A CRITICAL REVIEW OF WELD METAL EMBRITTLEMENT

SEVERAL TYPES OF EMBRITTLEMENT IN FERROUS ALLOY WELDS HAVE BEEN POSTULATED, INCLUDING POSTWELD HEAT TREATMENT (STRESS RELIEF) EMBRITTLEMENT, TEMPER EMBRITTLEMENT, AND CREEP EMBRITTLEMENT. THE EFFECTS OF THESE FORMS OF EMBRITTLEMENT ON WELD METAL ITSELF ARE CONSIDERED. INITIALLY, THE EFFECTS OF WELDING PROCESS ON THE NOTCH TOUGHNESS OF AS-DEPOSITED WELDS ARE DISCUSSED. THE PHENOMENOLOGICAL ASPECTS OF EACH TYPE OF EMBRITTLEMENT ARE THEN DESCRIBED, FOLLOWED BY AN EXAMINATION OF VARIOUS PROPOSED MECHANISMS OF EMBRITTLEMENT. FEW STUDIES HAVE BEEN CONDUCTED IN WHICH THE SEVERAL FORMS OF EMBRITTLEMENT HAVE BEEN SIMULTANEOUSLY EVALUATED IN ONE MATERIAL. THEREFORE, QUALITATIVE COMPARISONS ARE MADE BASED UPON AVAILABLE INFORMATION. THE MAJOR FACTORS AFFECTING THE THREE FORMS OF EMBRITTLEMENT ARE ALLOY COMPOSITION, PURITY AND MICROSTRUCTURE. THE WELDING PROCESS IS IMPORTANT THROUGH ITS EFFECT ON PURITY AND MICROSTRUCTURE. /AUTHOR/