In the first section of the paper, a summary will be given of the various defects which can develop in rails subjected to high axle loads, such as corrugations, gross plastic deformation and abrasive wear of the railhead, checking and spalling, shelling and transverse defects.

The second section of the paper will cover in detail the developmental work on high-strength alloyed rail steels conducted at Broken Hill Proprietary Co. Ltd. Melbourne Research Laboratories. An essential part of the work has been the development of techniques for laboratory simulation of industrial rail production and on-site welding procedures. Various other material properties have also been used in assessing material types.

The major emphasis of the work has been directed to optimizing the mechanical properties of three rail steel types, namely: chromium-columbium-vanadium steels, chromium-vanadium steels, and chromium-molybdenum steels. Fully pearlitic steels exhibiting yield strengths greater than 900 MPa have been developed without adversely influencing other mechanical properties. The steels can be flash butt welded using modified procedures.