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

Pangang Group Panzhihua Steel & Vanadium Co., Ltd.

Pangang Group Research Institute Co., Ltd.

Pangang Group Company Ltd.

Ming Zou

Yong Deng

Hua Guo

Jun Yuan

Zhenyu Han

Chunjian Wang

Jihai Jia

Quan Xu

Dongsheng Mei

Dadong Li

Li Tang

Chongmu Chen

Yuan Wang

Yun Zhao

Gongming Tao

Ruoxi Li

Dawei Yang

Hui Yao

Yanzhong Wang

Jianhua Liu

Ming Liu

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.

Method for heat treatment of hypereutectoid steel rail

The present invention provides a heat treatment method of turnout track comprising performing an accelerated cooling on the turnout track to be treated having a railhead tread with a temperature of 650-900&#xb0; C. so as to obtain the turnout track with full pearlite metallographic structure, wherein the accelerated cooling velocity performed on the working side of railhead of the turnout track is higher than that performed on the non-working side of the railhead of the turnout track. The present invention provides a turnout track obtained with a heat treatment process as depicted therein. The turnout track in present invention has good straightness; both the hardness and tensile strength of the working side of railhead are higher than that of the non-working side of railhead.

Heat treatment method of turnout track and the turnout track

The present disclosure discloses a heat treatment method for a bainitic turnout rail, which includes: naturally cooling the turnout rail at a temperature in an austenite region after being finishing rolled to 450-480&#xb0; C. at a tread center of a rail head of the turnout rail; accelerated cooling the naturally cooled turnout rail to 230-270&#xb0; C. at the tread center of the rail head, a cooling rate at the tread center and a non-working side of the rail head being 1.5-5.0&#xb0; C./s, a cooling rate at the working side of the rail head increasing by 0.1-1.0&#xb0; C./s based on 1.5-5.0&#xb0; C./s; continuously accelerated cooling the working side, the tread center and the non-working side of the rail head at a cooling rate of 0.05-0.25&#xb0; C./s to decrease a temperature of the tread center of the rail head to 265-270&#xb0; C.; and finally, naturally cooling the turnout rail to an ambient temperature.

Heat treatment method for bainitic turnout rail

A high carbon content and high strength heat-treated steel rail including by weight 0.80-1.20% carbon, 0.20-1.20% silicon, 0.20-1.60% manganese, 0.15-1.20% chromium, 0.01-0.20% vanadium, 0.002-0.050% titanium, less than or equal to 0.030% phosphorus, less than or equal to 0.030% sulfur, less than or equal to 0.010% aluminum, less than or equal to 0.0100% nitrogen, and iron. The steel rail has excellent wear resistance and plasticity and can satisfy the requirement for overloading. A method for producing the steal rail by heating a slab to a heating temperature, multi-pass rolling, and accelerated cooling, wherein a maximum heating temperature (&#xb0; C.) of said slab is equal to 1,400 minus 100[% C], [% C] representing the carbon content (wt. %) of said slab multiplied by 100.

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Panzhihua, China

Ming Zou