Mechanical and microstructural behaviour of a particulate reinforced steel for structural applications

Low density, high modulus, and potentially improved wear resistance are the major benefits of a ferrous composite material. A BS S.156 (4%NiCrMo)gear steel reinforced with 15 vol.-% titanium diboride particles has been demonstrated for possible high performance structural applications. This composite has been produced by a powder metallurgy/mechanical milling processing route, to give a homogeneous distribution of fine reinforcement particles. The composite tensile strength was 90% of the matrix in the fully heat treated condition, with ductility of up to 6%. However, martensite formation and hence the hardenability was found to be suppressed in the composite. A fatigue study indicated that the titanium diboride particles did not appear to contribute to crack initiation in the composite.