ASTM A193 Grade B8 Specification

ASTM A193 Grade B8 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 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 is a heat-treated, work-hardened (or both) austenitic stainless steel further divided into class 1, class 2 & class 2B, each having a distinguished tensile strength. ASTM A193 specification covers requirements for chemical composition, mechanical properties, hardness, heat-treatment and recommended nuts-washers for Grade B8 Fasteners.

Tensile Class

Property Description
Class 1 Carbide Solution Treated
Class 2 Carbide Solution Treated & Strain Hardened
Class 2B Carbide Solution Treated & Strain Hardened

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

A; The 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 1A All Sizes 75 30 30 50 223 HBW or 96 HRB


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

Class 2BB		 2 and under 95 75 25 40
over to 2-1/2 inclusive 90 65 30 40
over 2-1/2 to 3 inclusive 80 55 30 40

A: Carbide Solution Treated
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 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