Room-temperature cleavage fracture of FeMnAIC steels

Alloys of the FeMnAlC system have been extensively studied in recent years, and perhaps their more attractive aspect is the possibility of obtaining different combinations of mechanical strength, ductility, and fracture toughness over a wide temperature range. For structural purposes, a good combination of mechanical strength and fracture toughness is desirable, and so far the most commonly used treatment is that involving quenching from temperatures within the austenitic field and subsequent aging for 15 hours within 500degreesC to 600degreesC. The resulting hardness and mechanical strength are high, but fracture behavior may be unacceptable for critical applications. Experiments concerning controlled cooling are under way, as an attempt to produce a good combination of strength and fracture toughness. In this communication, we discuss a specific feature of fracture behavior revealed by specimens submitted to one of the processing conditions under study.