1. Steel plate grade: GR.50W
2. Specification: plate thickness ≤100mm
3. Steel plate size, shape, weight requirements and allowable deviations
Steel plate size, shape, weight requirements and allowable deviations shall comply with the provisions of ASTM A6/6M.
4. Technical requirements
4.1 Chemical composition (melting composition) shall comply with ASTM A709/A709M-11 and Table 1.
Brand CSiMnPSCuNiCrTiVAlCEA709-50W≤0.150.15-0.501.00-1.50≤0.025≤0.0100.20-0.40≤0.500.40-0.70≤0.0250.01-0.10≥0.020≤0.48 Note 1: The permissible deviation of the chemical composition of the finished steel plate shall comply with the corresponding provisions of SATM A709/709M-11.
Note 2: Carbon equivalent is calculated as CE=C+Mn/6+ (Cr+Mo+V) /5+ (Cu+Ni) /15.
Note 3: Atmospheric corrosion resistance index I=26.01 (%Cu) +3.88 (%Ni) +1.20 (%Cr) +1.49 (%Si) +17.28 (%P)-7.29 (%Cu) (%Ni) -9.10 (%Ni) (%P) -33.39 (%Cu) ≥6.0
Note 4: If necessary, trace NB element can be added to refine the austenite grain, and the actual content is indicated in the warranty.
American standard ASTM A709-50W bridge plate technical requirements for American Bridges
4.2 Mechanical properties test
4.2.1 Transverse sample of tensile sample is taken. Nominal thickness of steel plate ≤3/4in.(≤20mm), tensile sample should be taken the full thickness of steel plate, sample size refer to A370 standard figure 3; The nominal thickness of the steel plate is >3/4in.(>20mm), the diameter of the tensile sample is 1/2 in.(12.5mm), the axis of the sample is located at 1/4 of the thickness of the steel plate, and the size of the sample is referred to A370 standard Figure 4. Details are provided in the section A6/A6M Standard Tensile Test for sample directions and preparation. The frequency of the test was one per batch.
4.2.2 Longitudinal samples of Charpy V-notched impact samples are taken, and the axis is located at 1/4 of the thickness of the steel plate. The frequency of the test was three impact specimens per batch. For details of sample sampling and preparation, see standard A673/A673M.
4.2.3 Mechanical properties shall comply with the provisions of Table 2.
Grade Thickness ≤4in (≤100mm) Thickness ≤50mm Thickness >50-≤100mm Yield strength (MPa) Tensile strength (MPa) Extension sample A Average impact power Average impact power L50mm (%) L=200mm (%) A709-50W345-520≥485≥21≥18≥20J≥27J Note 1 : The plate is wider than 600mm steel plate, and the elongation is allowed to be reduced by 2%.
4.3 Delivery status
The steel plate is delivered in hot rolled or controlled rolled condition, allowing normalizing or tempering treatment.
In order to improve toughness, it is allowed to use a cooling method that is faster than the cooling rate in the air, but the steel plate should be tempered, and the tempering temperature range is 1100 to 1300℉(595 to 705℃), and indicated in the material list.
5. Surface quality
5.1 The surface of the steel plate shall not have bubbles, scars, cracks, folds, inclusions and pressed into the oxide sheet, and shall not have stratification
5.2 The surface shall have a thin layer of iron oxide and rust that does not hinder the surface inspection, and the iron oxide will fall off due to pressing
Non-significant roughness, scratches, corrugations caused by rolls and other local defects are allowed, but not more than half of the thickness tolerance, and the minimum thickness of the steel plate should be guaranteed;
5.3 Grinding method is allowed to eliminate surface defects, but welding shall not be allowed;
6. Flaw detection
According to requirements, steel plates with thickness of 6/5in.(30mm) and above can be ultrasonic inspected in accordance with ASTM A435, and grade II is qualified.
The steel plate to be inspected should be indicated in the purchase details.
7. Testing and inspection
7.1 Batch
Each batch consists of steel plates of the same furnace number, the same thickness, and the same delivery status, and each batch weighs < 49.2ton(<50 tons).
7.2 The number of tests and the preparation and retesting of samples are in accordance with the requirements of ASTM A6/A6M standard.
8. Steel plate logo
Surface spray mark: grade, conforming standard, batch number, pot number, inch size, etc.
Side identification: brand number, lot number, material number, inch size, etc
