INFLUENCE OF TITANIUM CARBIDE PARTICULATE REINFORCEMENT ON CYCLIC STRESS RESPONSE, CYCLIC STRAIN RESISTANCE AND FRACTURE OF STEEL-BASED METAL-MATRIX COMPOSITES

摘要

A study has been made to understand the role of composite microstructure and test temperature on cyclic stress response, cyclic strain resistance, low-cycle fatigue life and mechanisms governing the cyclic fracture behavior of tool steel metal matrix discontinuously-reinforced with titanium carbide (TiC) particulates. Two different volume fractions of the carbide particulate reinforcement phase, in the tool steel metal matrix, are considered. The composite microstructure had near similar particle size distribution. The tool steel/TiC{sub}p metal-matrix composites were cyclically deformed under fully-reversed total strain-amplitude control cyclic straining, giving fatigue lives of less than 10{sup}4 cycles to failure. At both ambient and elevated temperatures, the cyclic strain resistance and resultant low-cycle fatigue life degraded with an increase in the discontinuous reinforcement phase in the tool steel metal matrix. The stress response characteristics of the composite microstructures are compared in order to rationalize the influence of reinforcement content and test temperature on cyclic strain amplitude-controlled fatigue and fracture behavior. The cyclic fracture behavior of the composite is discussed in light of concurrent and mutually interactive influences of composite microstructural effects, matrix deformation characteristics, cyclic plastic strain amplitude and concomitant response stress.