SU1300946A1 - Method of producing rails - Google Patents

Abstract

The invention relates to the heat treatment of high-carbon and low-alloy steel rails and can be used in metallurgical plants producing railway rails. The aim of the invention is to improve the quality by increasing the mechanical properties, structural strength parameters and straightness of the rails. The billet is subjected to step-by-step diffusion annealing, then rolled in a pre-cleaning and finishing cage with a total compression of the head 21-30%, after which the head, neck, and rail strip base are subjected to differential cooling and self-discharging, and induction heating for the hardening of the rail strip is performed with the temperature of the end of the self-tempering 500-650 s, followed by differentiation by cooling the elements of the rail strip. 7 hp F-ly, 3 tabl i (L: D 4 35

Description

The invention relates to the heat treatment of rail rails of high carbon and low alloy steels and can be used in metallurgical plants producing railway rails.

The aim of the invention is to improve the quality by increasing the mechanical properties, structural strength parameters and straightness of the rails.

The following method I) II method is carried out as follows.

Two grades of steel were smelted; high carbon type M 76 and low alloyed Cr-Si-Mn steel type 75HGS. At the same time, in carbon steel, the mass fraction of the elements was,% g 0.78 С; , 05 Mp; 0.35 Si; 0.028 S; 0.032 Р m 0.115 As (АС, 725 and АС в 755 ° С, and А5,695 ° С and АГ, 635 ° С, jlHf205 ° С), and in low-alloyed - 0.79 С; 1.0 MP; 0.48 Si; 0.84 Cr; 0.06 V; Xie; 0.025 S and OOA P (AU 735 and AU, 780 C, and Ar, 705 and Ap, 640 ° C, 245 ° C).

The steel was poured into a mold 1 on a plate with a section of 120x120 mm, which were subsequently rolled into blanks. Then, the blanks were loaded into the furnace and, when heated for rolling onto rail strips (rail of type P18), were subjected to stepwise diffusion / annealing of the first heating stage for 3.5 h, with a speed of 3.5 h, the subsequent heating with a speed of 80–100 deg / h to 1250 C, holding at a given temperature of 2.0 hours. After performing the second stage of the Dried Annealing, the furnace temperature was lowered to 1–30 ° C, kept for 2.0 h and subjected to rolling on rail strips.

When rolling blanks on rail strips, the head was compressed in the shiversalny preparatory KPET by 22% and in the finishing one by 4% with the total compressed} 1 26% The duration of the pause between the passage was 6 ° C (and between the end of the deformation and diffraction of 2 mm) - 9 Ci Okhlayr head; ali up to 580®С at a speed of 15 degrees / s (kakshovki s), and a teigu eg the bottom of the platform approximately up to this non-temperature from CKopocTJ 8 degrees / s to the structure of the sorbant “At the end of the difference laddeni made a self-vacation

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for 20 s “After self-tempering, the head of the rail strip was subjected to high-frequency heating up to 930 C with exposure to an inductor at the end of heating for 30 s. At the exit from the soiibi heating of the quenching machine, the strip was placed in the differential cooling zone, with the head cooled, (given up to 470 C at a speed of 14 GD / s, and the neck and sole to 325 ° C at a speed of 7 deg / s, then whether the self-outflow and the final cooling of all elements of the rail strip to the ambient air temperature.When performing the noted technological operations, the rail strip during the movement was fixed in a straight-line position.,

The limestone method was carried out barely.,

After rolling, the rail strip of the day-time 25–50 m cooled, and up to 600– 650 ° C. at an ambient air temperature on special refrigerators at a speed of 2 degrees / s, then the rail strip entered the rail-hardening machine, where, in the process of continuous movement at a speed of 25 s / s, it entered the sys- tem of inductors to heat the head to a predetermined temperature, which according to the technological instruction, it was 990-1020 ° C “Immediately after heating, the head of the rapeseed was cooled by a water-air mixture at a rate of 8 deg / s to a temperature of 560-580 С, and then finally cooled by water tnoj temperature during the movement through the machine relsozakalochnuyu underrail strip to elastically bend the sole (is convex head) with a bending radius in the area of heating and cooling to be 20 m ",

Technological skeleton of sequential movement of the strip through the rail solenoid unit of the next section of the setting rollers (bending of reps begins) - its heating and curvature retention (active zone), the bending of the rail to the sole along a given radius occurs - output section & where the rail strip rectifies,

According to a known method, a rail strip dvihset-c h rail assembly unit through systems sections, which

Metal quality of carbon steel rails

standard composition and low alloy

Cr-Si-Mn composition type 75HGS.

CDoftCTBa rails made of carbon steel of standard grade

Minus sign compressing lips.

Table I

table 2

Secondly, it is gradually bent to a maximum in the active zone, and then after quenching, the strip enters the section of the rollers of the rollers, where the rail bends to the side opposite to the original bend.

However, this technological method does not completely remove the original curvature, as a result of which it is 150-200 mm over the length of the entire strip.

When heat treated according to the aforementioned method, the rail strip goes through all technological operations with continuous movement through a system of rollers arranged in a horizontal plane relative to the base. Therefore, the curvature in the vertical plane is almost absent and is 10 mm at a length of 50 m, which meets the tolerances along the curvature of the hardened rails.

- As shown by the experimental test data, as a result of using the proposed rail production method, the quality of the metal improves in terms of eliminating structural laxity and location of non-metallic inclusions (Table 1). At the same time, the austenite grain size dp of carbon steel decreases by 1-2 points 2-3 points - dp of low-alloyed Cr-Si-Mn steel type 75HGS. Dp of both steel grades (carbon and low-alloyed), the size of the blocks D decreases in the range from 510-495 to 400-325-10%, the micro-stress increases and from 0.85-0.92 to 1.2-1.35- 10 as well as a raft

The dislocation rate is p from 0.95-1.35 to 40% of the heating of the rail head, 2.85-3.9 cm. The complex of physicomechanical properties and parameters of structural strength increases (Tables 2 and 3),

Claims (1)

Invention Formula The races are kept at 880-980 C for 20-40 s. 7. A method according to claim 1, characterized in that the differentiated cooling of the rail strip during quenching is carried out according to the mode: for a head up to 520-420 C at a speed of 10-18 degrees / s, for a neck and a sole to ZZO-ZOO C at a speed of 5-8 degrees / s, followed by secondary cooling of all elements of the profile to ambient temperature. 1. A method of manufacturing rails, including obtaining a billet by hot deformation, heating the billet and rolling onto a rail strip in the pre-finishing and finishing cages, interrupted cooling after rolling, quenching from induction heating and self-tapping, characterized in that increase mechanical properties, structural strength five five 0 five 0 and the straightness of the rails, the billet when heated for rolling is subjected to stepwise diffusion annealing, rolling is carried out with a total compression of the head 21-30%, cooling after rolling is carried out differentially by profile elements followed by self-tempering, and hardening is also carried out by differential cooling of elements rail strip profile e 2, the method according to claim I, characterized in that step diffusion annealing is carried out at a temperature range of 1080-1280 ° C, while at 1080-1200 ° C for 2-5 hours at 1220-1280 ° C for 1-3 h | at 1180-1080 ° C for 1-3 hours 3, a method according to claim 1, characterized in that the rolling in the pre-finishing stand is carried out with a compression of the head 18-25%, in the finishing stand 3-5% with duration of interdeformational and postdeformation pauses 2-10 s and 2-16 s, respectively. 4, the method according to claim 1, which differs from jo-yi and so that differentiated o: cooling after rolling is carried out up to 6 ° -500 ° C with a speed of 10-20 degrees / s for a head and 2-14 degrees / s for neck and foot strip. 5, a method according to claim 1, characterized in that the self-emptying of the rail strip is carried out within 15-25 seconds immediately after cooling from the rolling heating, 6, the method according to i, about tl and h a - y sch. And the fact that after induction heating the rail head 50 The races are kept at 880-980 C for 20-40 s. 7. A method according to claim 1, characterized in that the differentiated cooling of the rail strip during quenching is carried out according to the mode: for a head up to 520-420 C with a speed of 10-18 degrees / s, for a neck and a sole to ZZO-ZOO C at a speed of 5-8 degrees / s, followed by secondary cooling of all elements of the profile to ambient temperature. 50 8, the method according to claim 1, characterized in that all technological operations are carried out while fixing the straight-line position of the track strip in the process of continuous movement Properties of rails manufactured by non-eco-alloyed Cr-St-Hn steel  The sign of usus is not a stress, Editor 3 Hodakova Compiled by V. Chinese Tehred L. Serdyukova Proofreader A. Zimokosov Order 2560 Draw 403 Subscription VNISh State Council of the USSR for inventions and discoveries 113035, Moscow, Zh-35, Raushsk .nab, d. A / 5 Production polygraph enterprise, Uzhgorod, st. Project, 4 T bpitsa 3