CN103014504A

CN103014504A - Steel special for high-hardness heat-treated steel rail

Info

Publication number: CN103014504A
Application number: CN201210523612XA
Authority: CN
Inventors: 李平; 智建国; 郑瑞; 蔚鯤; 李德虹
Original assignee: Baotou Iron and Steel Group Co Ltd
Current assignee: Baotou Iron and Steel Group Co Ltd; Inner Mongolia Baotou Steel Union Co Ltd
Priority date: 2012-12-08
Filing date: 2012-12-08
Publication date: 2013-04-03

Abstract

The invention relates to steel special for a high-hardness heat-treated steel rail. The steel is characterized in that it comprises the following chemical components by weight: 0.70-0.82% of C, 0.13-0.60% of Si, 0.65-1.25% of Mn, less than or equal to 0.15% of Cr, less than or equal to 0.025% of P, less than or equal to 0.30% of S, and less than or equal to 0.004% of Al. The steel has optimized components, and after a heat treatment on the steel, the steel rail hardness can be enhanced, thus satisfying the requirements of all curve engineering steel rails of a Saudi Arabia light rail project.

Description

A kind of high rigidity heat-treated rail special steel

Technical field

The present invention relates to a kind of high rigidity heat-treated rail special steel, belong to the metal material field that metallurgical industry is produced.

Background technology

Along with the transportation by railroad cause at a high speed, the development of heavily loaded direction, to the performance of rail is also corresponding more and more higher requirement proposed.The demanding rail level smooth degree of the raising of speed.Heavy duty accelerated the side grinding of rail, vertically abrasion and undulatory wear.That high speed or heavy duty all require the higher steel rail material of obdurability, to improve the use properties of rail.

Baogang makes great efforts the international rail of developing market in the market of basing on our country, play an active part in international competitive bidding.Baogang and Saudi Arabia have signed outlet 54E1 heat-treated rail contract, and this batch rail is used for Riyadh light rail segment of curve.

Summary of the invention

The purpose of this invention is to provide a kind of high rigidity heat-treated rail special steel that can satisfy Saudi Arabia's Riyadh light rail project curve engine request.

Steel composition of the present invention forms, and its chemical ingredients comprises by weight percentage: C:0.70～0.82%, Si:0.13～0.60%, Mn:0.65～1.25%, Cr :≤0.15%, P :≤0.025%, S :≤0.030% and Al :≤0.004%;

Thermal treatment temp control: rail head of rail fillet temperature is 980～1020 ℃, and rail head of rail tread temperature is 920～940 ℃;

The gas content of steel (mass ratio) H≤2.5ppm(liquid state), O≤20ppm, N≤100ppm;

Described steel heat obtains full nodular troostite tissue, mechanical property: tensile strength 〉=1175MPa, elongation 〉=9%, rail head tread hardness: 350～390HBW after processing.

Advantage of the present invention is: the steel Composition Design is reasonable, by thermal treatment, rail hardness is improved, and can satisfy the requirement of this batch Saudi Arabia steel rail bending lineman journey.

Description of drawings

Fig. 1 is rail transverse section hardness test figure.

Embodiment

The 54E1 heat-treated rail of Baogang outlet Saudi Arabia, through scientific and technical personnel's working experience with in the test of 25kg vacuum induction furnace, the composition range of designing steel grade is as shown in table 1.

The Composition Design of table 1 steel grade, w%

C

Si

Mn

Cr

P

S

Al

0.70～0.82

0.13～0.60

0.65～1.25

≤0.15

≤0.025

≤0.030

≤0.004

Technical process is: (casting blank specification is 280mm * 380mm) to converter smelting → LF stove refining → VD stove refining → continuous casting.

THE INDUSTRIAL TRIAL 15 stove steel, concrete process parameter control is as follows:

1) converter production

The carbon content of converter terminal molten steel, phosphorus content and tapping temperature are as shown in table 2.

The composition of table 2 converter tapping and temperature

Value	The tapping carbon content, %	The tapping phosphorus content, %	Tapping temperature, ℃
				Scope	0.08～0.24/0.14	0.002～0.017/0.010	1618～1640/1632

2) refining VD stove is produced

The dark vacuum tightness of VD stove, dark vacuum time, soft blow time are as shown in table 3.

Table 3 refining-VD stove smelting parameter

Value	Dark vacuum tightness, kPa	Dark vacuum time, min	The soft blow time, min
				Scope	0.046～0.080/0.060	15～18/16	8～12/10

3) continuous casting production

Continuous casting superheating temperature and pulling rate control are as shown in table 4.

Table 4 continuous casting superheating temperature and pulling rate control

Value	Superheating temperature, ℃	Pulling rate, m/min
			Scope	16～28/24	0.58～0.65/0.61

4) strand gas control

The control of steel billet gas is as shown in table 5.

The control of table 5 steel billet gas

Value	H?,ppm	O?,ppm	N?,ppm
				Scope	1.1～1.8	20	44

So far finished the bloom production of steel of the present invention, below for adopting the technique of described bloom production rail, technical process is: steel billet → process furnace heating → beam-and-rail Rolling With Universal Mill.

5) steel rolling production

The steel billet start rolling temperature was 1158 ℃ and 1170 ℃ to steel billet greater than 3.5 hours heat-up time in process furnace.

6) rail head of rail quenches and produces

The actual measurement temperature of rail head of rail quenching heating is as shown in table 6.

Table 6 hardening of rails Heating temperature

Value	Rail head of rail fillet temperature, ℃	Rail head of rail tread temperature, ℃
			Scope and mean value	980～1020	920～940

7) end properties check

Finished product mechanical properties test result such as table 7, transverse section hardness is as shown in table 8.

Table 7 finished product mechanical properties test result and requirement

Value	Tensile strength, MPa	Elongation, %	Rail head tread hardness, HBW
				Scope and mean value	1190～1280/1235	10.5～13.5/12.0	374～399/385
Saudi Arabia's technical protocol	≥1175	≥9	350～390

Table 8 transverse section hardness

By table 7,8 as seen, the mechanics property of rail of production satisfies Saudi Arabia department fully to the mechanical property requirements of rail, so the selection of steel grades is rational.

Claims

1. high rigidity heat-treated rail special steel, it is characterized in that: its chemical ingredients is by weight percentage: C:0.70～0.82%, Si:0.13～0.60%, Mn:0.65～1.25%, Cr :≤0.15%, P :≤0.025%, S :≤0.030% and Al :≤0.004%; Thermal treatment temp control: rail head of rail fillet temperature is 980～1020 ℃, and rail head of rail tread temperature is 920～940 ℃; Its gas content H≤2.5ppm(liquid state), O≤20ppm, N≤100ppm.

2. high rigidity heat-treated rail special steel according to claim 1 is characterized in that: after the described steel heat processing, obtain full nodular troostite tissue, mechanical property: tensile strength 〉=1175MPa, elongation 〉=9%, rail head tread hardness: 350-390HBW.