ASTM A193 Grade B8M Class 2 Specification for high tensile bolts, screws, stud bolts, anchor bolts, threaded rods and other externally threaded fasteners, made from 316 stainless steel.

ASTM A193 Grade B8M Class 2 is a standard material specification for corrosion resistant 316 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 B8M Class 2 is strain hardened & carbide solution treated 316 stainless steel having minimum requirement of 100 ksi, yield 50 ksi with 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 B8M Class 2 Fasteners.

Chemical Composition

Element	Austenitic Stainless Steel
	AISI 316 / 316L
	CompositionA, %
Carbon	0.08 max
Manganese	2.00
Phosphorus	0.045 max
Sulfur	0.030 max
Silicon	1.00 max
Chromium	16.00 - 18.00
Nickel	10.00 - 14.00
Molybdenum	2.00 - 3.00

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

Mechanical Properties

Tensile Class	Diameter, Inch min, ksi	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	110	95	15	45	321 HBW or 35 HRC
						over 3/4 to 1 inclusive	100		80	20	45
over 1 to 1-1/4 inclusive	95	65	20	45
over 1-1/4 to 1-1/2 inclusive	90	50	30	45

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.