Pangang Group Panzhihua Iron & Steel Research Institute Co., Ltd.

Pangang Group Panzhihua Steel & Vanadium Co., Ltd.

Pangang Group Research Institute Co., Ltd.

Jun Yuan

Ming Zou

Yong Deng

Hua Guo

Zhenyu Han

Chunjian Wang

Dadong Li

Jihai Jia

Chongmu Chen

Yuan Wang

Hui Yao

Ruoxi Li

Dawei Yang

A moderate-strength steel rail is provided. The chemical composition of the moderate-strength steel rail in weight percentages includes carbon 0.70-0.90 wt %, silicon 0.08-0.65 wt %, manganese 0.69-1.31 wt %, chromium 0.10-0.25 wt %, phosphorus ≤0.020 wt %, sulfur ≤0.020 wt %, and iron 96.85-98.41 wt %. According to a production method for the moderate-strength steel rail of the present invention, the moderate-strength steel rail produced has a rail hardness of 350-370 HB, a wear amount of ≤0.40 g, a contact fatigue life of ≥50,000 times, and a 610 mm steel rail waist opening ≤3.0 mm/400 mm.

Moderate-strength steel rail and production method thereof

The present invention discloses a method for producing a hypereutectoid steel rail resistant to contact fatigue. The method includes performing molten iron desulphurization, converter smelting, LF refining, RH refining, continuous casting and billet heating, rolling and heat treatment after rolling to obtain a steel rail; the heat treatment after rolling includes performing accelerated cooling and air cooling on the center of a tread of a rail head, both sides of the rail head and the center of a rail bottom of the steel rail obtained after rolling, wherein the starting cooling temperature of the accelerated cooling is 650-900° C., the cooling rate is 1.0-5.0° C./s, and the final cooling temperature is 400-550° C.; and after reaching the final cooling temperature, the accelerated cooling is stopped and it is air-cooled to room temperature. The hypereutectoid steel rail has higher purity, better contact fatigue resistance and good wear resistance.

Method for producing hypereutectoid steel rail resistant to contact fatigue

The invention relates to a turnout rail production technology, in particular to a deeply-hardened-surface turnout rail with high degree of undercooling and the preparation method thereof. The invention aims to solve the technical problem by providing a deeply-hardened-surface turnout rail with high degree of undercooling featured in even hardness distribution and a deeply hardened surface layer and the preparation method thereof. The method is described as follows: feeding molten iron for converter smelting&#x2192;furnace rear argon blowing station&#x2192;LF refining&#x2192;RH vacuumization&#x2192;casting steel blanks&#x2192;slow cooling in the slow cooling pit&#x2192;austenitic homogenization&#x2192;rail rolling&#x2192;heat treatment; in the converter smelting process, adding 0.2-0.3% Cr, 0.04-0.06 V and 0.75-0.80% C; the heat treatment process is divided into two cooling stages. The turnout rail prepared with the method described in the invention has a deeper deeply-hardened surface layer; the hardness is distributed more evenly, the anti-contact fatigue performance is higher and the resistance to wearing is ideal.

Deeply-hardened-surface turnout rail with high degree of undercooling and the preparation method thereof

Provided is a manufacturing method for high-toughness and plasticity hypereutectoid rail, including: a. hot rolling the steel billet into rail; b. blowing a cooling medium to the top surface of railhead, wherein, the two sides of railhead and the lower jaws on the two sides of railhead after the center of top surface of rail is air-cooled to 800-850&#xb0; C., and cooling the rail until the center temperature of the top surface is 520-550&#xb0; C.; c. stop blowing the cooling medium to the lower jaws on the two sides of railhead, continue blowing the cooling medium to the top surface of railhead and the two sides of railhead, and air cool the rail to room temperature after the surface temperature of railhead is cooled to 430-480&#xb0; C. The resulting hypereutectoid rail has higher toughness and plasticity than existing products, which is suitable for heavy-haul railway, especially for small radius curve sections.

High-toughness and plasticity hypereutectoid rail and manufacturing method thereof

The present invention relates to a heat treatment method for increasing the depth of hardening layer in a steel rail, and belongs to the field of steel rail production process. The technical problem to be solved in the present invention is to provide a heat treatment method for increasing the depth of hardening layer in a steel rail and a steel rail obtained with the method. The method comprises the following steps: cooling a finished rolling steel rail by natural cooling, till the temperature at the center of rail head surface is 660&#x2dc;730&#xb0; C.; cooling the steel rail by accelerated cooling at 1.5&#x2dc;3.5&#xb0; C./s cooling rate, till the temperature at the center of rail head surface is 500&#x2dc;550&#xb0; C.; increasing the cooling rate by 1.0&#x2dc;2.0&#xb0; C./s and further cooling down the steel rail, till the temperature at the center of rail head surface is 450&#xb0; C. or lower; then, stopping the accelerated cooling, and cooling down the steel rail by air cooling to room temperature. With the heat treatment method disclosed in the present invention, a deep-hardening layer thicker than 25 mm can be obtained in the rail head part, the portion within 25 mm depth below the surface layer of rail head has hardness equivalent to the hardness of the surface layer of rail head, and the rail head is in a pearlite structure across its cross section. Thus, the service performance of the steel rail against the wearing incurred by the contact between the train wheels and the steel rails can be improved.

Heat treatment method for increasing the depth of hardening layer in a steel rail and steel rail obtained with the method

The present invention discloses a method for preparing hypereutectoid steel rail in which the composition of the billets adopted is: C: 0.86-1.05 wt. %; Si: 0.3-1 wt. %; Mn: 0.5-1.3 wt. %; Cr: 0.15-0.35 wt. %; Cu: 0.3-0.5 wt. %; P: 0.02-0.04 wt. %; S: &#x2264;0.02 wt. %; Ni: &#xbd;-&#x2154; of the content of Cu; at least one of V, Nb and Re; Fe and unavoidable impurities of the rest. The present invention further provides a hypereutectoid steel rail prepared by the foregoing method. By the hypereutectoid steel rail preparation method provided by the present invention, the high-carbon billets with a specific composition provided by the present invention can be made into hypereutectoid steel rails with good corrosion resistance and tensile properties.

Hypereutectoid steel rail and preparation method thereof

The present invention discloses a method for heat treatment of hypereutectoid steel rail, including the following steps: holding the temperature of the steel rail of which temperature is above 900&#xb0; C. after finish rolling, conducting a first cooling stage for the steel rail at the first cooling speed after the temperature holding to reduce the temperature of railhead surface layer of the steel rail to 700-750&#xb0; C., conducting a second cooling stage for the steel rail at the second cooling speed to reduce the temperature of railhead surface layer of the steel rail to 550&#xb0; C., conducting a third cooling stage for the steel rail at the third cooling speed to reduce the temperature of railhead surface layer of the steel rail to 450&#xb0; C. or less, and continuing to cool the steel rail in the air. While obtaining good tensile property, the steel rail treated by the method for heat treatment provided by the present invention can effectively reduce secondary cementite and have excellent resistance to abrasion and contact fatigue. The product is particularly suitable for heavy rails.

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Panzhihua, China

Jun Yuan