Chemical element composition of Chinese grade hot-rolled or normalized bridge steel Q500qD
Q500qD Similar Grade Lookup Table
Steel Grade Designation Method:
The steel grade designation consists of several parts: the initials of the Chinese pinyin for yield strength, the specified minimum yield strength value, the first letter of the pinyin for "bridge", and a quality grade symbol.
Example: Q500qD
- Q — the first letter of the pinyin for "yield strength" in "bridge steel"
- 500 — the specified minimum yield strength value, in MPa
- q — the first letter of the pinyin for "bridge"
- D — quality grade D
Chemical Composition & Mechanical Properties of Q500qD Steel
Q500qD Chemical composition of thermomechanically rolled steel
| Grade | Quality grade |
Chemical Composition(Quality Fraction)/% | |||||||||||||||||||||||||||||||||||||||||
| C | Si | Mnᵃ | S | P | Nbᵇ | Vᵇ | Tiᵇ | Alsᵇ,ᶜ | Cr | Ni | Cu | Mo | N | ||||||||||||||||||||||||||||||
| ≤ | ≤ | ||||||||||||||||||||||||||||||||||||||||||
| Q500q | D | 0.11 | 0.55 | 1.00~ 1.70 |
≤0.015 | ≤0.025 | 0.010~ 0.090 |
0.010~ 0.080 |
0.006~ 0.030 |
0.010~ 0.045 |
0.8 | 0.7 | 0.3 | 0.3 | 0.008 | ||||||||||||||||||||||||||||
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a: According to the agreement between the supplier and the buyer, the maximum manganese content can be 2.00%. b: Al, Nb, V, and Ti can be added to steel individually or in combination. When added individually, they should comply with the provisions in the table. When added in combination, at least one alloying element should be added at the lower limit specified in the table, and Nb+V+Ti≤0.22%. c: When using total aluminum (Alt) content for calculation, the total aluminum content should be 0.015%~0.050%. |
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Q500qD Chemical composition of tempered steel
| Grade | Quality grade |
Chemical Composition(Quality Fraction)/% | |||||||||||||||||||||||||||||||||||||||||
| C | Si | Mn | S | P | Nbᵃ | Vᵃ | Tiᵃ | Alsᵃ,ᵇ | Cr | Ni | Cu | Mo | N | ||||||||||||||||||||||||||||||
| ≤ | |||||||||||||||||||||||||||||||||||||||||||
| Q500q | D | 0.11 | 0.55 | 0.80~ 1.70 |
≤0.015 | ≤0.025 | 0.005~ 0.060 |
0.010~ 0.080 |
0.006~ 0.030 |
0.010~ 0.045 |
≤0.80 | ≤0.70 | ≤0.30 | ≤0.30 | ≤0.0080 | ||||||||||||||||||||||||||||
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Note: Element B can be added at a rate of 0.0005% to 0.0030%. a: Al, Nb, V, and Ti can be added to steel individually or in combination. When added individually, they should comply with the provisions in the table. When added in combination, at least one alloying element should be added at the lower limit specified in the table, and the content of Nb+V+Ti should be less than 0.22%. |
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Q500qD Mechanical properties of steel
| Grade | Quality grade | Tensile testᵃ,ᵇ | Impact testᶜ | ||||||||||||||||||||||
| Lower yield strength ReL/MPa | Tensile strength Rm/MPa |
Elongation after fracture A/% |
Temperature℃ | Impact absorption energy KV2/J |
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| Thickness≤50mm | 50mm<Thickness≤100mm | 100mm<Thickness≤150mm | |||||||||||||||||||||||
| ≥ | ≥ | ||||||||||||||||||||||||
| Q500q | D | 500 | 480 | — | 630 | 18 | -20 | 120 | |||||||||||||||||
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a: When the yield strength is not obvious, Rp0.2 can be measured instead of the lower yield strength. b: For tensile tests, transverse specimens are taken. c: Longitudinal specimens are used for impact testing. |
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Technical Requirements
Smelting Method:
Steel is smelted in a converter or electric furnace and should undergo ladle refining.
Delivery Status:
Steel shall be delivered in any of the following conditions: hot-rolled, normalized, thermomechanically rolled, or quenched and tempered (including online quenching + high-temperature tempering), and this shall be specified in the quality certificate.
Steel delivered in the normalized condition shall undergo high-temperature tempering (tempering temperature not less than 580 ℃) when cooled in a medium with a faster cooling rate than air.
For steel with atmospheric corrosion resistance intended for exposed use, it shall be delivered in any of the above-mentioned conditions other than normalized. When cooled using a cooling method with a faster cooling rate than air, tempering treatment shall be performed.
Mechanical Properties:
The mechanical properties of the steel shall conform to the specifications in the table above.
The Charpy (V-notch) impact absorbed energy shall be calculated as the arithmetic mean of a set of three specimens. One specimen may have a single value lower than the value specified in the table above, but it shall not be lower than 70% of the specified value.
For Charpy (V-notch) impact tests on steel plates with a thickness less than 12 mm, auxiliary specimens shall be used. For steel plates >8 mm to <12 mm, the auxiliary specimen size shall be 10 mm × 7.5 mm × 55 mm, and the test result shall not be less than 75% of the value specified in Table 8; for steel plates 6 mm to 8 mm, the auxiliary specimen size shall be 10 mm × 5 mm × 55 mm, and the test result shall not be less than 50% of the value specified in Table 8; steel plates with a thickness less than 6 mm shall not undergo impact testing.
If the impact test results of the steel plate do not comply with the requirements of 7.4.2 and 7.4.3, another set of three specimens shall be taken from the same batch of steel plates for testing. The arithmetic mean of the six specimens shall not be lower than the specified value, and two specimens are allowed to be lower than the specified value, but only one specimen is allowed to be lower than 70% of the specified value.
The reduction of area in the Z-direction of the steel thickness shall comply with the requirements of GB/T5313.
Surface Quality:
The surface of the steel shall be free from harmful defects that affect its use, such as bubbles, scale, cracks, folds, inclusions, and pressed-in iron oxide scale. The steel shall not have visually visible delamination.
The surface of the steel is permitted to have a thin layer of iron oxide scale, rust, and inconspicuous roughness, texture, scratches, and other localized defects caused by pressed-in iron oxide scale and rolling mill rolls, provided these do not hinder inspection of surface defects. However, their depth shall not exceed half the tolerance of the steel thickness, and the minimum permissible thickness of the steel shall be guaranteed.
Surface defects of the steel may be removed by grinding or other methods. The cleaned area shall be smooth and without sharp edges. The cleaning depth shall not exceed the negative deviation of the steel thickness, and the minimum permissible thickness of the steel shall be guaranteed.
Defects are permitted in steel strip, but the defective portion shall not exceed 6% of the total length of each coil of steel strip.
With the agreement of both the supplier and the buyer, the surface quality of the steel may comply with the provisions of GB/T14977.
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