ASTM A193 TECHNICAL DATA

ASTM A193 Grades and Markings

The ASTM A193 specification encompasses the standard that covers high-strength low-alloy steel shapes for bolting material used for pressure valves, flanges, vessels, and fittings for high-temperature applications.  For this specification, it covers wire, bars, bolts, studs, stud bolts, and screws. They are mainly used in chemical construction and petroleum applications. Although, this material is often utilized in national coarse thread pitches, but threads are specified 8 threads per inch (tpi) for diameters above 1 inch when being used in traditional applications.

ASTM A193 Mechanical Properties

ASTM A193 Specifications for Mechanical Properties governs the material specification defining mechanical properties, chemical composition, and preferential heat treatment. In addition, it governs product marking, hardness requirements, certifications, and more. ASTM A193 defines both SI (Metric) and inch-pound units.

Marking of Ferritic Steels
Grade	Grade Symbol
B5	B5
B6	B6
B6X	B6X
B7	B7
B7M	B7M or B7M
B16	B16
B16+	B16R

Marking of Austenitic Steels
Class	Grade	Grade Symbol
Class 1	B8 B8C B8M B8P B8T B8LN B8LMLN B8CLN B8ML4CuN	B8 B8C B8M B8P B8T B8F or B8LN B8G or B8MLN B8Y or B8CLN B8YY or B8ML4CuN
Class 1A	B8A B8CA B8MA B8PA B8TA B8LNA B8LMLNA B8NA B8MNA B8MLCuNA B8CLNA B8ML4CuNA	B8A B8B or B8CA B8D or B8MA B8D or B8MA B8H or B8PA B8J or B8TA B8L or B8LNA B8K or B8MLNA B8V or B8MA B8W or B8MNA B9K or B8MLCuNA B8Z or B8CLNA B8ZZ or B8MLCuNA
Class 1B	B8N B8MN B8MLCuN	B8N B8Y or B8MN B9J or B8MLCuN
Class 1C	B8R B8RA B8S B8SA	B9A or B8R B9B or B8RA B9D or B8S B9F or B8SA
Class 1D	B8 B8M B8P B8LN B8MLN B8N B8MN B8R B8S B8CLN B8ML4CuN	B94 B95 B96 B97 B98 B99 B100 B101 B102 B103 B104
Class 2	B8 B8C B8P B8T B8N B8M B8MN B8MLCuN	B8SH B8CSH B8PSH B8TSH B8NSH B8MSH B8YSH B8JSH
Class 2B	B8M2 B8	B9G or B8M2 B9
Class 2C	B8M3	B9H or B8M3

A To meet the tensile requirements, the Brinell hardness shall be over 200 HBW (93 HRB).
B Class 1 is solution treated. Class 1A is solution treated in the finished condition for corrosion resistance; heat treatment is critical due to physical property requirement.
Class 2 is solution treated and strain hardened. Austenitic steels in the strain-hardened condition may not show uniform properties throughout the section particularly in sizes over 3⁄4 in. in diameter.
C For sizes 3⁄4 in. in diameter and smaller, a maximum hardness of 241 HBW (100 HRB) is permitted.
D 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.

ASTM A193 Materials & Chemical Properties

Material and Chemical Property Requirements for the ASTM A193 governs minimum and maximum carbon, phosphorus, manganese, sulfur, silicon, chromium, nickel, and molybdenum percent content of steel fasteners within the ASTM A193 specification. The properties also include the minimum tempering temperature requirements. 

A Values are maximums unless a range or a minimum is indicated. Where ellipses appear in this table, there is no requirement and the element need not be determined or reported. The intentional addition of Bi, Se, Te, and Pb is not permitted.
B Product Analysis—Individual determinations sometimes vary from the specified limits as shown in the tables. The several determinations of any individual element in a heat may not vary both above and below the specified range. Product variation limits are over for maximums, over or under for ranges, and under for minimums, unless otherwise indicated.
C Typical steel compositions used for this grade include 4140, 4142, 4145, 4140H, 4142H, and 4145H. ^D For bar sizes over 31⁄2 in. [90 mm], inclusive, the carbon content may be 0.50 % max. For the B7M grade, a minimum carbon of 0.28 % is permitted, provided that the required tensile properties are met in the section sizes involved, the use of AISI 4130 or 4130H is allowed.
D For bar sizes over 31⁄2 in. [90 mm], inclusive, the carbon content may be 0.50 % max. For the B7M grade, a minimum carbon of 0.28 % is permitted, provided that the required tensile properties are met in the section sizes involved, the use of AISI 4130 or 4130H is allowed.
E Total of soluble and insoluble.