FRACTURE BEHAVIORS AND CHARACTERISTICS OFWC/ NiCrMo STEEL MATRIX COMPOSITES

The f racture behaviors and f ractographic features of WC/ NiCrMo steel mat rix composites under 12kinds of conditions, af ter austenization between 960 ～ 1040 ℃ then quenching and tempering, were investigatedusing single edge notched beam ( SENB) method, SEM and elect ron theory analysis. The result s show that thematerial has high st rength (σ_bb ～2200 MPa, σ_bc ～3000 MPa) and hardness ( HRC 62～68), and higher fracturetoughness (～30 MPa ·m^1/2 ) . The main fractographic appearances are WC cleavage, quasi-cleavage of mat rix, dispersed dimples and dimple bands. The numerous hard phases of WC (～40 %) play a dominant role in f racture toughness and fracture behavior, and based on the alloy elect ron theory, both of the containing carbon st ructure unit swith high bond st rength andα-Fe (Ni) st ructure unit s with more lattice elect ron in mat rix cont ribute to the st rongtough support to the hard phases and lead to micro-ductility during fracture.