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.