ASTM A193 Grade B8N Class 1B Specification for high tensile bolts, screws, stud bolts, anchor bolts, threaded rods and other externally threaded fasteners, made from 304N stainless steel.

ASTM A193 Grade B8N Class 1B is a standard material specification for high strength 304N 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 B8N Class 1B is a carbide solution treated 304N stainless steel having minimum tensile requirement of 80 ksi, yield 30 ksi and maximum hardness limit of 223 HBW or 96 HRB. This specification covers requirements for chemical composition, mechanical properties, hardness, heat-treatment and recommended nuts-washers for Grade B8N Class 1B Fasteners.

Chemical Composition

Element	Austenitic Stainless Steel
	AISI 304N / UNS S30451
	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
Molybdenum	0.10 - 0.16

^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, maxA
								Class 1B	All Sizes	80	35	30	40	223 HBW or 96 HRB

Heat Treatment: Carbide Solution Treated
A: For sizes 3⁄4 in. in diameter and smaller, a maximum hardness of 241 HBW (100 HRB) is permitted.