This standard is the amended edition of TB/T2635-1995 Technical Specification for Heat Treated Rails by referring to foreign technical standards for heat-treated rails.
　　The main changes with respect to TB/T2635-1995 Technical Specification for Heat Treated Rails are listed below：
　　-Terms and definitions are added;
　　-Code No. for heat treated rails are added;
　　-New heat treated rail types U75V and U76NbRE are added;
　　-Chemical composition for rail steel U71Mn is adjusted;
　　-Hardness scope for rail head section is added and sampling locations for rail head chin are increased;
　　-Indicators for yield strength and section shrinkage ratio in tensile test are canceled;
　　-Drop weight test is canceled;
　　-Twist tolerance for heat treated rail end before straightening is added.
　　This standard is proposed and managed by Standards and Metrology Research Institute of the Ministry of Railways.
　　This standard is jointly drafted by Wang Shuqing， Zhou Qingyue， Zhu Mei， Zhan Xinwe19 Xu Quan and Hong Haifeng.
　　Drafting organizations： Metal and Chemical Research Institute， Standard & Metrology Research Institute， Research and Development Center of China Academy of Railway Sciences， Pangang Group Company Ltd. and the rail welding section of Hohhot Railway Administration.
　　This standard is first issued in March 1995 and this is the first amended edition.