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This standard was proposed by the Ministry of Metallurgical Industry of the People's Republic of China and was developed by the Standardization Research Institute of Ministry of Metallurgical Industry.
Technical Specification of 38~50kg/m Steel Rail for Railway
This standard is applicable to the steel rail with nominal weight of 38~50kg/m used for railway.
I. Technical Specification
1. Manufacture:
(1) The steel rail is made of killed steel smelted by open-hearth furnace and oxygen converter.
(2) To ensure there is no shrinkage cavity and harmful segregation on the steel rail, the steel billet equivalent to exterior part of ingot and butt shall be cut off sufficiently.
(3) The production process free from producing white points in steel rail shall be adopted.
2. Chemical composition (smelting analysis) of steel shall meet the requirements specified in Table 1.
Table 1
No. Steel grade Chemical composition, %
C Si Mn Cu P S
Not greater than
1 U 71 0.64~0.77 0.13~0.28 0.60~0.90 0.040 0.050
2 U 74 0.67~0.80 0.13~0.28 0.70~1.00 0.040 0.050
3 U71Cu 0.65~0.77 0.15~0.30 0.70~1.00 0.10~0.40 0.040 0.050
4 U71Mn 0.65~0.77 0.15~0.35 1.10~1.50 0.040 0.040
5 U70MnSi 0.65~0.75 0.85~1.15 0.85~1.15 0.040 0.040
6 U71MnSiCu 0.65~0.77 0.70~1.10 0.80~1.20 0.10~0.40 0.040 0.040
3. Mechanical property and processing property:
(1) The mechanical property of steel rail in delivery condition shall meet the requirements specified in Table 2.
Table 2
No. Steel grade Tensile strength σb kilogram force /mm2
(N/mm2) Percentage elongation δ5
%
Not less than
1
2
3
4
5
6 U71
U74
U71Cu
U71Mn
U70MnSi
U71MnSiCu 80 (785)
80 (785)
80 (785)
90 (883)
90 (883)
90 (883) 10
9
9
8
8
8
Note: for the tensile sample cut from sample rail through hot saw, its percentage elongation in the test result is allowable to be 1% (absolute value) lower than the specified value.
(2) The steel rail shall be subjected to drop hammer test. There shall be no rupture phenomenon between two supporting points when the sample is hit once. Record the deflection for reference.
4. Rail end quenching:
The form of quenched layer shall be cap form. Its technical requirements shall refer to those specified in the annex.
Notes: ① As required by the purchaser, the steel rail without quenching at the rail end and drilling hole at one or two ends may be supplied.
② Quenching is not carried out at the rail end for the steel grade of U70MnSi and U71MnSiCu.
5. The length of steel rail:
The specified lengths of standard rail are 12.5m and 25m.
The length of curve shortened rail
12.5m steel rail 12.46, 12.42 and 12.38m.
25m steel rail 24.96, 24.92 and 24.84m.
Length of undergauge rail:
12.5m steel rail 9, 9.5, 11, 11.5 and 12m.
25m steel rail 21, 22, 23, 24 and 24.5m.
The matching quantity of undergauge rails shall be noted in the contract through negotiation of supplier and demander, which shall not be greater than 15% of the total weight of the one order batch.
6. Permissible dimension deviation of steel rail shall meet those specified in Table 3.
Table 3
Item Permissible deviation/mm
Steel rail section Head width ±0.5
Web thickness +1.0
-0.5
Web height ±0.5
Height +0.8
-0.5
Base width +1.0
-2.0
Asymmetry Rail head 0.5
Rail base 1.0
Length (20℃) ≤12.5m ±6
>12.5m ±10
End face inclination (vertical and horizontal directions) 1.0
End bent (within 1m) Upward 0.5
Downward
Left and right
Bolt hole Diameter ±1.0
Position
Notes: ① For straightened rails, the negative deviation for height of deformed part of rails 0.3mm higher than tabular value is permissible.
② When the manufacturer has not installed rail end straightening machine, the steel rail end bending is measured with 1m ruler, and its maximum bending shall not be greater than the following values:
Upward bending 0.8mm
Downward bending 0.2mm
Left/right bending 0.8mm
7. Appearance:
(1) The rolled steel rail shall avoid bending as much as possible. The straightened steel rail shall be straight without wave bending and hard bending. The even bending of steel rail shall not be greater than 0.5/1,000 of the full length of steel rail.
The steel rail torsion shall not be greater than 1/10,000 of the full length of steel rail.
(2) The middle of rail base shall not be 0.5mm higher than both sides, and the protruding parts at the contact area of both sides of steel rail and fishplate shall be cleared off.
(3) The surface of steel rail shall be free from crack, wrinkles and transverse scratch. The scar with depth not exceeding 1mm, indentation, bumping and few streaks are allowable, and the longitudinal scratch depth shall not exceed 0.5mm. There shall be free from streak at 1/3 of rail base center, and other defect depth shall not exceed 0.5mm.
The end face of steel rail and surface of bolt hole shall be free from shrinkage cavity residue, layering and cracks; burrs on the edges shall be removed.
Foreword I
I. Technical Specification
II. Acceptance Rules and Test Methods
III. Marking and Quality Certificate
Annex Technical Requirements for Rail End Quenching
