ASTM A193 Grade B8M 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 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 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 B8M Fasteners.

Tensile Class

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

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	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	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	25	45
over 1-1/4 to 1-1/2 inclusive	90	50	30	45

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.