Grades of Steel for Ship Building
| Property | Grade A | Grade B | Grade D | Grade E |
| % of Carbon | 0.21 max | 0.21 max | 0.21 max | 0.18 max |
| % of Manganese | 2.5 times %C min | 0.8 times %C min | 0.6 times %C min | 0.7 times %C min |
| % of Silicon | 0.5 max | 0.35 max | 0.1 – 0.35 | 0.1 – 0.35 |
| % of Phosphorous | 0.035 max | 0.035 max | 0.035 max | 0.035 max |
| % of Sulphur | 0.035 max | 0.035 max | 0.035 max | 0.035 max |
| % of Aluminum | – | – | 0.015 min | – |
| Ultimate Tensile Strength (N/mm2) | 400-520 | |||
| Yield Strength (N/mm2) | 235 | |||
| % Elongation | 22 | |||
| Temperature at which Impact test is done (deg Cel) | NA | 0 | -20 | -40 |
High Tensile Steels (HTS)
- HTS can be used effectively in highly stressed areas of the ship.
- They have less thickness for same strength compared to normal steel.
- Strength is increased by adding grain refining elements such as (% Al: 0.015 min, % Nb: 0.02 – 0.05, % V: 0.05 – 0.10, % Ti: 0.02)
- High tensile steels are expressed as AH 36, BH 40, etc.
- AH stands for High tensile steel of Grade A
- The number represents minimum yield strength in N/mm2 (32 means minimum 315 N/mm2, 36 means minimum 355 N/mm2, 40 means minimum 390 N/mm2)
- Ultimate Tensile Strength for the above three numbers are: 32 —-> 440 – 590 N/mm2, 36 —-> 490 – 620 N/mm2 and 40 —-> 510 – 650 N/mm2
- It should be noted that for Grade A steel temperature for impact test is not applicable. At the same time for Grade AH steel impact test to be carried out at zero degree Celsius.
See Also: Heat Treatment in Marine Steels