ASTM A193 Grade B8T Class 2 Specification

ASTM A193 Grade B8T Class 2 Specification for high tensile bolts, screws, stud bolts, anchor bolts, threaded rods and other externally threaded fasteners, made from 321 stainless steel.

ASTM A193 Grade B8T Class 2 is a standard material specification for corrosion resistant 321 stainless steel fasteners such as bolts, screws, studs, threaded rods and other externally threaded parts, for use in high tensile, high temperature and special purpose applications such as pressure piping & pressure vessels bolting. Grade B8T is strain hardened and carbide solution treated stainless steel having minimum tensile requirement of 100 ksi, yield 50 ksi and maximum hardness limit of 321 HBW or 35 HRC. This specification covers requirements for chemical composition, mechanical properties, hardness, heat-treatment and recommended nuts-washers for Grade B8T Class 2 Fasteners.

Chemical Composition

Element Austenitic Stainless Steel
AISI 321 / 321H
CompositionA, %
Carbon 0.08 max
Manganese 2.00
Phosphorus 0.045 max
Sulfur 0.030 max
Silicon 1.00 max
Chromium 17.00 - 19.00
Nickel 9.00 - 12.00
Titanium 5 x Carbon Content - 0.70
Nitrogen 0.10 max

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 2A		 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

Heat Treatment: Carbide Solution Treated and Strain Hardened
A: 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 8T ASTM A240 TP321

Fasteners

Commonly Produced B8T 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