ASME SA-210 C compared to 25MnG
ASME SA-210 C Boiler tube VS 25MnG Boiler tube
Comparison of domestic 25MnG Boiler tube and ASME SA-210 C Boiler tube
1, the scope of chemical composition
Chinese brands 25MnG is the United States ASME material SA-210C and SA-106C corresponding steel. The chemical composition ranges are "overlapping" with those of ASME SA-210C and SA-106C. The chemical composition of 25MnG, SA-210C and SA-106C is required by the corresponding standard.
| Material | C(%) | Mn(%) | Si(%) | P(%) | S(%) |
| 25MnG | 0.22-0.30 | 0.7-1.00 | 0.17-0.37 | ≤0.030 | ≤0.030 |
| SA-210 C | ≤0.35 | 0.29-1.06 | ≥0.10 | ≤0.035 | ≤0.035 |
| SA-106C | ≤0.35 | 0.29-1.06 | ≥0.10 | ≤0.035 | ≤0.035 |
It should be noted that SA-210C and SA-106C carbon steel pipe chemical composition is the same in both ASME / ASTM SA-210 and SA-106 standards, the carbon content only provides the upper limit; The national standard GB5310-1995, 25MnG carbon content not only provides a range of values, and the carbon content of the upper limit to 0.30%. Appropriate reduction of carbon content is conducive to welding. At the same time, in order not to reduce the mechanical properties, 25MnG the Mn content of the lower limit has also been adjusted accordingly - by the ASME standard 0.29% to 0.7%. In addition, GB 5310-1995 on the material of harmful elements P and S than ASME SA-210C and SA-106C lower limit, while the upper and lower limits of the Si element, and SA-210C and SA-106C Only the lower limit value is specified for the Si element.
This shows that the chemical composition of 25MnG carbon steel pipe in the SA-210C material range, and more scientific and reasonable than the SA-210C, more stringent requirements.
2, mechanical properties
Comparison of Mechanical Properties of 25MnG and SA-210C Steel Pipe.
| Material | Tensile Strength(MPa) | Yield Strength(MPa) | Elongation(%) | Hardness（HRB） | |
| 25MnG | ≥485 | ≥275 | 20 | ≤179 | |
| SA-210 C | ≥485 | ≥275 | ≥27(WT:6.5) | ≤179 | |
| ≥28(WT：7.0) | ≤89 | ||||
The corresponding standard 25MnG and SA-210C tensile strength and yield strength requirements are identical. Moreover, in the ASME SA-210 material standard does not require steel to ensure that the impact of work, can be seen, the national standard GB5310-1995 than the ASME standard material standards more stringent.
In addition, ASME SA-210 material standards require steel pipe to ensure hardness, and 25MnG pipe hardness index in full compliance with the requirements of the ASME standard SA-210 material standards.
3, smelting and processing methods
GB5310-1995 25MnG and other steel smelting method is mainly the United States with reference to the relevant standards, for a smelting, can also be used for secondary smelting. From the heat treatment process point of view, 25MnG requires cold drawn steel pipe at 900 ℃ ~ 930 ℃ for normalizing; SA-210C on the cold drawn steel pipe can be selected sub-critical annealing, complete annealing and normalizing, such as steel pipe for the boiler water wall Fire, so two kinds of materials, heat treatment process is exactly the same.
According to the information provided by steel mills, regardless of whether the user is according to 25MnG or SA-210C order, steel mills are using the same smelting and processing methods.
4, allowable stress
SA-210C and 25MnG because the chemical composition and mechanical properties to ensure the same value, so the design allows the same stress. The allowable stress values for 25MnG obtained in accordance with the ASME code for allowable stresses are the same as the allowable stress values for SA-210C given in ASME Volume II,
| S,Mpa | 350℃ | 400℃ | 450℃ | ||
| 25MnG | 134 | 101 | 67 | ||
| SA-210 C | 134 | 101 | 67 | ||
It can be seen, according to GB5310-95 25MnG material manufactured with double signs of the conditions. In accordance with the requirements of the ASME code to supplement the elongation and hardness of the two tests under the premise that the 25MnG can be marked as SA-210C, that is, the material has a double mark. Test data show that, 25MnG the elongation and hardness can meet the requirements of the ASME specification SA-210C.
25MnG and SA-210C boiler tube in the whole production process of the smelting method, manufacturing process, production technology parameters, metal consumption, scrap rate and manufacturing costs are not different. In summary, 25MnG is SA-210C.