ASTM A193 Grade B8C Specification

ASTM A193 Grade B8C Specification for high tensile bolts, screws, stud bolts, anchor bolts, threaded rods and other externally threaded fasteners, made from 347 stainless steel.

ASTM A193 Grade B8C is a standard material specification for corrosion resistant grade 347 stainless steel fasteners, for use in high tensile, high temperature and special purpose applications such as pressure piping & pressure vessels bolting. Grade B8C 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 B8C Fasteners.

Tensile Class

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

Chemical Composition

Element Austenitic Stainless Steel
AISI 347
CompositionA, %
Carbon 0.08 max
Manganese 2.00
Phosphorus 0.045 max
Sulfur 0.030 max
Silicon 1.00 max
Chromium 17.00 - 19.00
Nickel 9.00 - 12.00
Columbium + tantalum 10 x Carbon Content - 1.10

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 HRBC


Class 2B		 3/4 and under 125 100 12 35

321 HBW or 35 HRC
over 3/4 to 1, inclusive 115 80 15 35
over 1 to 1-1⁄4, inclusive 105 65 20 35
over 1-1⁄4 to 11⁄2, inclusive 100 50 28 45

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

Recommended Nuts & Washers

Nut Specification Washer Specification
ASTM A194 Grade 8C ASTM A240 TP347

Fasteners

Commonly Produced B8C 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