ASTM A193 Grade B8T Specification

ASTM A193 Grade B8T 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 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 a heat-treated, work-hardened (or both) austenitic stainless steel further divided into class 1 and class 2, each having a distinguished tensile strength. This specification covers requirements for chemical composition, mechanical properties, hardness, heat-treatment and recommended nuts-washers for Grade B8T Fasteners.

Tensile Class

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

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 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

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 8T ASTM A240 TP321

Fasteners

Commonly Produced B8T 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