| Conventional steel rails used on the small radius curve track can hardly meet the increasing demand for wear resistance and are vulnerable to wave shaped wear and shelling defects. To address this problem, the heat treated (SQ) high strength steel rail was developed at Pangang during the ‘Seventh-Year Plan’. Extensive and in-depth investigations were conducted on slack quenching characteristics as well correlation between quenching process parameters and depth, hardness, structure and property of hardened layer. As a result, an off-line heat treatment system was developed and an integrated proprietary technology has evolved at Pangang. After heat treatment, the hardened layer exhibited a hardness of HRc36.0-42.0, σ0.2≥798MPa, σb≥1155MPa, δ≥10% and achieved a prolongation of service life by more than one time compared with the as-rolled rails. The physical quality is comparable to the SQ rails supplied from Japan. Thus this technology has filled in a gap in the domestic market. |