What are the mechanical properties of SA258 Grade C?
SA204 Grade B is an alloy steel plate standardized under the ASME Boiler and Pressure Vessel Code (Section II, Part A). It is a molybdenum steel specifically designed for moderate to high-temperature service in welded pressure vessels, particularly boiler drums and shells.
The mechanical properties for SA258 Grade C are defined by the ASME SA-258 specification. A key characteristic of this specification is that the required mechanical properties vary significantly by plate thickness. Below are the key properties from the standard.
Important Note: SA-258 has multiple grades (A, B, C). This data is for Grade C specifically.
Mechanical Properties (ASME SA-258 Grade C)
The tensile requirements are divided into four thickness ranges.
1. For plates ≤ 0.5 inch (12.5 mm):
Tensile Strength: 55 – 75 ksi (380 – 515 MPa)
Yield Strength (Min): 30 ksi (205 MPa)
Elongation in 2 in. (50 mm), Min: 23%
2. For plates > 0.5 to 1.0 inch (12.5 to 25 mm):
Tensile Strength: 53 – 73 ksi (365 – 505 MPa)
Yield Strength (Min): 28 ksi (195 MPa)
Elongation in 2 in. (50 mm), Min: 24%
3. For plates > 1.0 to 1.5 inches (25 to 40 mm):
Tensile Strength: 51 – 71 ksi (350 – 490 MPa)
Yield Strength (Min): 26 ksi (180 MPa)
Elongation in 2 in. (50 mm), Min: 25%
4. For plates > 1.5 to 2.0 inches (40 to 50 mm):
Tensile Strength: 50 – 70 ksi (345 – 485 MPa)
Yield Strength (Min): 25 ksi (170 MPa)
Elongation in 2 in. (50 mm), Min: 26%
Summary Table: SA258 Grade C Properties by Thickness
| Plate Thickness | Tensile Strength (ksi) | Yield Strength, Min (ksi) | Elongation, Min (in 2") |
|---|---|---|---|
| ≤ 0.5 in | 55 – 75 | 30 | 23% |
| > 0.5 to 1.0 in | 53 – 73 | 28 | 24% |
| > 1.0 to 1.5 in | 51 – 71 | 26 | 25% |
| > 1.5 to 2.0 in | 50 – 70 | 25 | 26% |
(For metric: 1 ksi ≈ 6.895 MPa)
Critical Application Notes:
No Mandatory Impact Toughness: The SA-258 specification does not require Charpy V-Notch impact testing. If the application requires notch toughness (e.g., for low-temperature startup), it must be explicitly specified as an additional requirement by the purchaser.
Heat Treatment: The plates are typically supplied in the as-rolled condition unless otherwise specified. Normalizing or stress relieving can be requested.
Primary Use Context: These properties are suitable for its intended applications-moderate-temperature structural components like furnace supports and fireboxes-where high strength is not the primary design driver.
Strength vs. Thickness: Note the clear trend of decreasing strength with increasing thickness, which is typical for as-rolled carbon steels.
In essence, the mechanical profile of SA258 Grade C is that of a general-purpose, moderate-strength carbon steel with properties that are highly dependent on the ordered plate thickness. For design, always use the values corresponding to the specific thickness being purchased.
Chemical composition of Product analysis for SA285 Grade C pressure vessel steel plate (Max %)
|
Steel Grade |
Main chemical composition of A285 Grade C |
||||
|
C |
Si |
Mn |
P |
S |
|
|
A285 Grade C |
0.28 |
0.08-0.45 |
0.98 |
0.035 |
0.035 |
What is SA258 Grade C?
Answer: SA258 Grade C is a carbon steel plate specification for pressure vessels, primarily used in industrial heating applications like fireboxes and superheater supports, designed for moderate elevated temperature service.
What is the chemical composition of SA258 Grade C?
Answer: Its composition is primarily carbon steel with controlled levels of Carbon (max 0.20%), Manganese (0.40-0.80%), Silicon (0.10-0.30%), and limited Phosphorus and Sulfur.
What are the mechanical properties of SA258 Grade C?
Answer: For plates up to 0.5 inches thick, it has a minimum tensile strength of 55-75 ksi (380-515 MPa) and a minimum yield strength of 30 ksi (205 MPa).
Is SA258 Grade C a carbon steel or alloy steel?
Answer: SA258 Grade C is classified as a carbon steel, as it does not contain significant intentional additions of alloying elements like chromium or molybdenum.
What is the primary application of SA258 Grade C?
Answer: Its primary use is in the fabrication of fireboxes, furnace supports, and similar components in boilers and heaters where temperatures are moderately elevated but oxidation resistance is less critical.
What is the maximum service temperature for SA258 Grade C?
Answer: It is typically used for service temperatures up to approximately 800°F (427°C), primarily in non-corrosive, low-stress support applications.
How does SA258 Grade C differ from SA258 Grade A and B?
Answer: The grades differ primarily in strength levels. Grade C offers higher tensile strength (55-75 ksi) compared to Grade A (47-67 ksi) and Grade B (50-70 ksi), with slight variations in chemistry.
Can SA258 Grade C be welded?
Answer: Yes, it has good weldability typical of low-carbon steels. Standard welding practices for carbon steel are generally applicable.
Does SA258 Grade C require impact testing?
Answer: Impact testing is not a mandatory requirement of the base specification but can be specified as an additional requirement by the purchaser if needed for the application.
Is SA258 Grade C suitable for pressure vessel shells?
Answer: While it is a pressure vessel quality plate, its typical use is more specialized for internal support structures in high-temperature environments rather than primary pressure-retaining shells in modern construction.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.
