ASTM A193 Grade B8S Specification

ASTM A193 Grade B8S Specification for high tensile bolts, screws, stud bolts, anchor bolts, threaded rods and other threaded fasteners, made from Alloy 218 / UNS S21800 / Nitronic 60 stainless steel.

ASTM A193 Grade B8S is a standard material specification for high strength, corrosion resistant Alloy 218 / UNS S21800 / Nitronic 60 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 B8S 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 B8S Fasteners.

Tensile Class

Property Description
Class 1C
Carbide Solution Treated
Class 1D

Chemical Composition

Element Austenitic Stainless Steel
Alloy 218 / UNS S21800 / Nitronic 60
CompositionA, %
Carbon 0.10 max
Manganese 7.00 - 9.00
Phosphorus 0.060 max
Sulfur 0.030 max
Silicon 3.50 - 4.50
Chromium 16.00 - 18.00
Nickel 8.00 - 9.00
Nitrogen 0.08 - 0.18

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 95 50 35 55 271 HBW or 28 HRC

Heat Treatment: Carbide Solution Treated

Recommended Nuts & Washers

Nut Specification Washer Specification
ASTM A194 Grade 8S ASTM A240 UNS S21800

Fasteners

Commonly Produced B8S Fasteners
Hex Bolts Heavy Hex Bolts Stud Bolts Threaded Rods Anchor Bolts
Eye Bolts Socket Head Cap Screws Countersunk Screws U Bolts Square Head Bolts