ASTM A193 Grade B8 Class 2 Specification

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ASTM A193 Grade B8 Class 2 Specification for high tensile bolts, screws, stud bolts, anchor bolts, threaded rods and other externally threaded fasteners, made from 304 stainless steel. ASTM A193 Grade B8 Class 2 is a standard material specification for corrosion resistant austenitic stainless steel fasteners, for use in high tensile, high temperature and special purpose applications such as pressure piping & pressure vessels bolting. Grade B8 Class 2 is a carbide-solution-treated & strain-hardened 304 stainless steel with minimum tensile requirement of 125 ksi, yield 100 ksi and maximum hardness of 35 HRC. This specification covers requirements for chemical composition, mechanical properties, hardness, heat-treatment and recommended nuts-washers for Grade B8 Class 2 Fasteners.


Chemical Composition

Element Austenitic Stainless Steel
AISI 304 / 304L
CompositionA, %
Carbon 0.08 max
Manganese 2.00
Phosphorus 0.045 max
Sulfur 0.030 max
Silicon 1.00 max
Chromium 18.00 - 20.00
Nickel 8.00 - 11.00

AThe intentional addition of Bi, Se, Te, and Pb is not permitted.


Mechanical Properties

Tensile Class Diameter, Inch Tensile Strength,
min, ksi
Yield Strength,
min, 0.2% offset,
ksi
Elongation
in 4D,
min, %
Reduction
of Area,
min, %
Hardness,
max


Class 2B,C
3/4 and under 125 100 12 35

321 HBW or 35 HRC
over 3/4 to 1 inclusive 115 80 15 35
over 1 to 1-1/4 inclusive 105 65 20 35
over 1-1/4 to 1-1/2 inclusive 100 50 28 50

B: Carbide Solution Treated and Strain Hardened
C: For diameters 11⁄2 and over, center (core) properties may be lower than indicated by test reports which are based on values determined at 1⁄2 radius.


Recommended Nuts & Washers

Nut Specification Washer Specification
ASTM A194 Grade 8 ASTM A240 TP304

Fasteners

Commonly Produced B8 Class 2 Fasteners
Hex Bolts Heavy Hex Bolts Stud Bolts Threaded Rods Anchor Bolts
Eye Bolts Socket Head Cap Screws Countersunk Screws U Bolts Square Head Bolts
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