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ASTM A193 Specification

ASTM A193 Specification covers high tensile alloy and stainless steel bolts including most popular grade B6, B7, B7M, B8, B8M, B8T, B16, etc.

ASTM A193 specification covers alloy and stainless steel bolting for pressure vessels, valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications. Several grades are covered, including ferritic steels and austenitic stainless steels designated B5, B6, B7, B8, B8M, etc. Selection will depend upon design, service conditions, mechanical properties, and high temperature characteristics. This specification is expressed in both inch-pound units and in SI units; however, unless the purchase order or contract specifies the applicable A193M specification designation (SI units), the inch-pound units shall apply

ASTM A193 Grades

Grade Raw Material
B6 13% Chromium Ferritic Steel
B7 Chromium Molybdenum Alloy Steel, Quenched & Tempered
B7M Chromium Molybdenum Alloy Steel, Quenched & Tempered
B16 Chromium-molybdenum-vanadium Alloy Steel, Quenched & Tempered
B8 AISI 304 Stainless Steel, Carbide Solution Treated
B8 Class 2 AISI 304 Stainless Steel, Carbide Solution Treated and Strain Hardened
B8M AISI 316 Stainless Steel, Carbide Solution Treated
B8M Class 2 AISI 316 Stainless Steel, Carbide Solution Treated and Strain Hardened
B8T AISI 321 Stainless Steel, Carbide Solution Treated
B8T Class 2 AISI 321 Stainless Steel, Carbide Solution Treated and Strain Hardened

ASTM A193 Properties

ASTM A193 Chemical Composition

Element Grade B6 Grade B7, 7M Grade B16 Grade B8 Grade B8M Grade B8T
Carbon 0.08-0.15 0.37-0.49 0.36-0.47 0.08 0.08 0.10 min
Manganese, max 1.00 0.65-1.10 0.45-0.70 2.00 2.00 1.00
Phosphorus, max 0.040 0.035 0.035 0.045 0.045 0.040
Sulfur, max 0.030 0.040 0.040 0.030 0.030 0.030
Silicon 1.00 max 0.15-0.35 0.15-0.35 1.00 1.00 1.00 max
Chromium 11.5-13.5 0.75-1.20 0.80-1.15 18.0-20.0 16.0-18.0 4.00-6.00
Molybdenum -- 0.15-0.25 0.50-0.65 -- 2.00-3.00 0.40-0.65
Vanadium -- -- 0.25-0.35 -- -- --
Aluminium, max -- -- 0.015 -- -- --

ASTM A193 Mechanical Properties

Grade Diameter, in. Tensile Strength, ksi Yield Strength ksi Elongation, % Reduction, % Hardness
B5 Up to 4, inclusive 100 80 16 50 --
B6 Up to 4, inclusive 110 85 15 50 --
B7 2.5 and under 125 105 16 50 321 HBW or 35 HRC
Over 2.5 to 4 115 95 16 50 321 HBW or 35 HRC
Over 4 to 7 100 75 18 50 321 HBW or 35 HRC
B7M 4 and under 100 80 18 50 235 HBW or 99 HRB
over 4 to 7 100 75 18 50 235 HBW or 99 HRB
B16 2.5 and under 125 105 18 50 321 HBW or 35 HRC
Over 2.5 to 4 110 95 17 45 321 HBW or 35 HRC
Over 4 to 8 100 85 16 45 321 HBW or 35 HRC
B8, B8M, Class 1 All Diameters 75 30 30 50 223 HBW or 96 HRB
B8, B8T, Class 2 3/4 and under 125 100 12 35 321 HBW or 35 HRC
Over 3/4 to 1, inclusive 115 80 20 45 321 HBW or 35 HRC
Over 1 to 1 1/4, inclusive 105 65 25 45 321 HBW or 35 HRC
Over 1 1/4 to 1 1/2, inclusive 100 50 30 45 321 HBW or 35 HRC
B8M, Class 2 3/4 and under 110 95 15 45 321 HBW or 35 HRC
over 3/4 to 1, inclusive 100 80 20 45 321 HBW or 35 HRC
over 1 to 1 1/4, inclusive 95 65 25 45 321 HBW or 35 HRC
M30 to M36, inclusive 620 345 30 45 321 HBW or 35 HRC

Recommended Nuts & Washers

Bolt Grade Nut Grade Washer Grade
B6 ASTM A194 Grade 6 Mild Steel
B7,7M ASTM A194 Grade 2H, 2HM ASTM F436
B16 ASTM A194 Grade 16 ASTM F436
B8 ASTM A194 Grade 8 SS 304
B8M ASTM A194 Grade 8M SS 316
B8T ASTM A194 Grade 8T SS 321