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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.