Chemical Composition
| Elements | A354 Grades BC, BD | A193 Grade B7 | ||
| **See Note Below | Chromium-Molybdenum | |||
| Range percent | Check
variation over percent |
Range percent | Check
variation over or under percent |
|
| Carbon... | -- | -- | *0.38-0.48 | 0.02 |
| Manganese... | -- | -- | 0.750-1.00 | 0.04 |
| Phosphorus, max... | 0.04 | 0.005 | 0.04 | 0.005 over |
| Sulphur, max... | 0.04 | 0.005 | 0.04 | 0.005 over |
| Silicon... | -- | -- | 0.20-0.35 | 0.02 |
| Chromium... | -- | -- | 0.80-1.10 | 0.05 |
| Molybdenum... | -- | -- | 0.15-0.25 | 0.02 |
| Elements | A193 Grade B16 Chromium-Molybdenum-Vanadium |
|||
| Range percent | Check
variation over or under percent |
|||
| Carbon... | 0.36-0.44 | 0.02 | ||
| Manganese... | 0.45-0.70 | 0.03 | ||
| Phosphorus, max... | 0.04 | 0.005 over | ||
| Sulphur, max... | 0.04 | 0.005 over | ||
| Silicon... | 0.20-0.35 | 0.02 | ||
| Chromium... | 0.80-1.15 | 0.05 | ||
| Molybdenum... | 0.50-0.65 | 0.03 | ||
| Vanadium... | 0.25-0.35 | 0.03 | ||
| Elements | A320 Grade L7 | A320 Grade L43 | ||
| Chromium-Molybdenum (AISI 4140, 4142, 4145) |
Nickel-Chromium-Molybdenum (AISI 4340) |
|||
| Range percent | Check
variation over percent |
Range percent | Check
variation over or under percent |
|
| Carbon... | *0.38-0.48 | 0.02 | 0.38-0.148 | 0.02 |
| Manganese... | 0.75-1.00 | 0.04 | 0.60-0.85 | 0.03 |
| Phosphorus, max... | 0.04 | 0.005 over | 0.04 | 0.005 over |
| Sulphur, max... | 0.04 | 0.005 over | 0.04 | 0.005 over |
| Silicon... | 0.20-0.35 | 0.02 | 0.20-0.35 | 0.02 |
| Nickel... | -- | -- | 1.65-2.00 | 0.05 |
| Chromium... | 0.80-1.10 | 0.05 | 0.70-1.90 | 0.03 |
| Molybdenum... | 0.15-0.25 | 0.02 | 0.20-0.30 | 0.02 |
*For bar sizes over 3-1/2 in. to 4 in., inclusive, the carbon content may be 0.50 pct. max.
** Any alloy steel capable of meeting the tensile requirements of Specification A354 may be used.
Tensile Requirements
| Grade | Diameter, in. | Min tempering temp F |
Tensile strength min psi |
Yield point min psi |
Elongation in 2 in. min pct |
Reduction of area min pct |
| A354 Grade BC | {2-1/2 and under {Over 2-1/2 to 4 incl. |
850 | 125,000 | 109,000 | 16 | 50 |
| A354 Grade BD | 1-1/2 and under | 850 | 115,000 | 99,000 | 16 | 45 |
| A193 Grade B7 Chromium- Molybdenum |
{2-1/2 and under {Over 2-1/2 to 4 incl. {Over 4 to 7 incl. |
850 | 150,000 | 125,000 | 14 | 35 |
| A193 Grade B16 Chromium- Molybdenum- Vanadium |
{2-1/2 and under {Over 2-1/2 to 4 incl. {Over 4 to 7 incl. |
1100 1100 1100 |
125,000 115,000 100,000 |
105,000 95,000 75,000 |
16 16 18 |
50 50 50 |
| A320 Grade L7 Chromium- Molybdenum |
2-1/2 and under | -- | 125,000 | 105,000 | 16 | 50 |
| A320 Grade L43 Nickel-Chromium- Molybdenum |
4 and under | -- | 125,000 | 105,000 | 16 | 50 |
Commonly used are the following grades of heat-treated alloy steel for high-pressure or extreme temperature service in diameters of 1/2 in. to 2 in., inclusive. Other grades and other diameters are available on special order.
ASTM A354, Grades BC and BD - heat-treated alloy steels for applications at normal atmospheric temperatures where high strength is required.
ASTM A193, Grade B7 - a heat-treated chromium-molybdenum steel widely used for medium high-temperature service.
ASTM A193, Grade B16 - a heat-treated chromium-molybdenum-vanadium steel for high-pressure, high-temperature service.
ASTM A320, Grade L7 - This grade is intended for low-temperature service down to minus 150ºF and has a minimum Charpy impact value of 15 ft-lb at this temperature. Sizes 2-1/2 in. and under.
ASTM A320, Grade L43 - The same properties offered by Grade L7 in sizes up to 2-1/2 are obtainable up to 4 in. in Grade L43.
