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Specifications

ASTM A193

The ASTM standard covers alloy steel and stainless steel bolts for high temperature or high pressure environments. ASTM A194 is the standard specification for carbon and alloy steel nuts for bolts used in equivalent high-pressure or high-temperature environments. This specification includes fasteners intended for use in pressure vessels, valves, flanges, and fittings.

ASTM A193 covers several other standard specifications not covered in this description including B5, B6, and B16.

A193 Grades

B7 Alloy steel, AISI 4140/4142 quenched and tempered
B8 Class 1 Stainless steel, AISI 304, carbide solution treated.
B8M Class 1 Stainless steel, AISI 316, carbide solution treated.
B8 Class 2 Stainless steel, AISI 304, carbide solution treated, strain hardened
B8M Class 2 Stainless steel, AISI 316, carbide solution treated, strain hardened

A193 Mechanical Properties

Grade Size Tensile ksi, min Yield, ksi, min Elong, %, min RA % min HBW HRC
B7 Up to 2-1/2 125 105 16 50 321 max 35 max
2-5/8 - 4 115 95 16 50
4-1/8 - 7 100 75 18 50
B8 Class 1 All 75 30 30 50 223 max 35 max
B8M Class 1 All 75 30 30 50 223 max 96 max
B8 Class 2 Up to 3/4 125 100 12 35 321 max 35 max
7/8 - 1 115 80 15 35
1-1/8 - 1-1/4 105 65 20 35
1-3/8 - 1-1/2 100 50 28 45
B8M Class 2 Up to 3/4 110 95 15 45 321 max 35 max
7/8 - 1 100 80 20 45
1-1/8 - 1-1/4 95 65 25 45
1-3/8 - 1-1/2 90 50 30 45

A193 Chemical Properties

Element B7 (AISI 4140) B8 (AISI 304) B8M (AISI 316)
Carbon 0.38 - 0.48% 0.08% max 0.08% max
Manganese 0.75 - 1.00% 2.00% max 2.00% max
Phosphorus, max 0.035% 0.045% 0.045%
Sulfur, max 0.040% 0.030% 0.030%
Silicon 0.15 - 0.35% 1.00% max 1.00% max
Chromium 0.80 - 1.10% 18.0 - 20.0% 16.0 - 18.0%
Nickel 8.0 - 11.0% 10.0 - 14.0%
Molybdenum 0.15 - 0.25% 2.00 - 3.00%