ASTM A193 Grade B8R Specification for high tensile bolts, screws, stud bolts, threaded rods and other externally threaded fasteners, made from UNS S20910 / XM-19 / Nitronic 50 stainless steel.

ASTM A193 Grade B8R is a standard material specification for high strength, corrosion resistant UNS S20910 / XM-19 / Nitronic 50 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 B8R is a carbide solution treated stainless steel further divided into class 1C and class 1D, both having a minimum tensile requirement of 100 ksi, yield 55 ksi and maximum hardness limit of 271 HBW or 28 HRC. This specification covers requirements for chemical composition, mechanical properties, hardness, heat-treatment and recommended nuts-washers for Grade B8R Fasteners.

Tensile Class

Property	Description
Class 1C	Carbide Solution Treated
Class 1D

Chemical Composition

Element	Austenitic Stainless Steel
	UNS S20910 / XM-19 / Nitronic 50
	CompositionA, %
Carbon	0.06 max
Manganese	4.00 - 6.00
Phosphorus	0.045 max
Sulfur	0.030 max
Silicon	1.00 max
Chromium	20.50 - 23.50
Nickel	11.50 - 13.50
Molybdenum	1.50 - 3.00
Nitrogen	0.20 - 0.40
Columbium + tantalum	0.10 - 0.30
Vanadium	0.10 - 0.30

^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 1C & 1D	All Sizes	100	55	35	55	271 HBW or 28 HRC

Heat Treatment: Carbide Solution Treated