If the desired mechanical properties are as described in 4.1.1 for material identified as Classes P-1 through P-7, or in 4.1.2 for material identified as Classes Q-1 through Q-7, the strength level desired can be based on hardness or the equivalent tensile or yield strength as shown in Tables 1-4. If the desired mechanical properties are as set forth in 4.1.3 for material identified as Classes R-1 through R-6, the strength level is based on yield strength as shown in Tables 5 and 6.

The user, after determining the mechanical property requirements of the critical section (that carrying the greatest stress) of the part, should select the composition or compositions from Tables 1-6 that fulfills these requirements and is most suitable for processing.

1. Scope

1.1 This practice covers the selection of steel bars according to section and to the mechanical properties desired in the part to be produced. This is not a specification for the procurement of steel. Applicable procurement specifications are listed in Section 5.

1.2 Several steel compositions intended for various sections and mechanical property requirements are presented in Tables 1-6. The criteria for placing a steel composition in one of the three general class designations, Classes P, Q, and R (described in Section 4) are as follows:

1.2.1 Classes P and Q should be capable of developing the mechanical properties shown in Tables 1-4 by liquid quenching from a suitable austenitizing temperature, and tempering at 800°F (427°C) or higher. A hardness indicated by tests made at a location shown in Fig. 1, A, B, or C, is taken as evidence that a composition is capable of meeting other equivalent mechanical properties shown in the tables. Normal good shop practices are assumed, with control of austenitizing and tempering temperatures, and mild agitation of the part in the quenching bath.

1.2.2 Class R should be capable of developing the mechanical properties shown in Tables 5 and 6 as hot rolled, by cold drawing, or by cold drawing with additional thermal treatment. The locations for obtaining tension tests are described in 6.2.

1.3 It is not implied that the compositions listed in the tables are the only ones satisfactory for a certain class and mechanical property requirement. Steels with lower alloy contents are often satisfactory through the use of special processing techniques.

1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

TABLE 1 Steels for Moderately Quenched PartsClasses P-1 Through P-7
(Applicable to oil-quenching or equivalent rate of heat-removal.)

Note 1—Steels listed as approved for a certain section or strength may be used for lighter sections and lower strengths.

Note 2—Steel composition numbers correspond to SAE, AISI, or ASTM designations. Those in italics are no longer considered standard grades due to decreased usage.

Note 3—An H-steel with the same grade designation as a standard SAE-AISI steel is capable of meeting the same section and strength requirements as the standard steel (see Specification A304), and is the preferred method of specification.

Note 4—Steels having a maximum carbon content of 0.40 % or over, or a hardness of HB 293 or over after heat-treating, are not recommended for applications involving welding.

^A 1 psi = 0.006895 MPa.

^B Minimum as-quenched hardness for obtaining desired hardness after tempering at 800°F (427°C) or higher.

^C 1 in. = 25.4 mm.

TABLE 2 Steels for Drastically Quenched PartsClasses P-1 Through P-7
(Applicable to water-quenching or equivalent rate of heat-removal See Note 5)

Note 1—Steels listed as approved for heavier sections or higher strengths may be used in the same conditions for lighter sections and lower strengths.

Note 2—Steel composition numbers correspond to ASE, AISI, or ASTM designations. Those in italics are no longer considered standard grades due to decreased usage.

Note 3—An H-steel with the same grade designation as a standard SAE-AISI steel is capable of meeting the same section and strength requirements as the standard steel (see Specification A304), and is the preferred method of specification.

Note 4—Steels having a maximum carbon content of 0.40 % or over, or a hardness of HB 293 or over after heat-treating, are not recommended for applications involving welding.

Note 5—Parts made of steel with a carbon content of 0.33 % or higher, where the section is under 1 1/2 in. (38.1 mm) should not be quenched in water without careful exploration for quench-cracking.

^A 1 psi = 0.006895 MPa.

^B Minimum as-quenched hardness for obtaining desired hardness after tempering at 800°F (427°C) or higher.

^C 1 in. = 25.4 mm.

^D These steels have insufficient hardenability for Class P-4, because of difference in test locations, but are satisfactory for other smaller sizes.

TABLE 3 Steels for Moderately Quenched PartsClasses Q-1 Through Q-7
(Applicable to oil-quenching or equivalent rate of heat-removal.)

Note 1—Steels listed as approved for heavier sections or higher strengths may be used in the same conditions for lighter sections and lower strengths.

Note 2—Steel composition numbers correspond to ASE, AISI, or ASTM designations. Those in italics are no longer considered standard grades due to decreased usage.

Note 3—An H-steel with the same grade designation as a standard SAE-AISI steel is capable of meeting the same section and strength requirements as the standard steel (see Specification A304), and is the preferred method of specification.

Note 4—Steels having a maximum carbon content of 0.40 % or over, or a hardness of HB 293 or over after heat-treating, are not recommended for applications involving welding.

Desired Minimum Hardness		Equivalent Tensile Strength, psiA	Equivalent Yield Strength, psiA	MinimumB As- Quenched Hardness		Class
						Q-1	Q-2	Q-3	Q-4	Q-5	Q-6	Q-7
						Diameter of Round (or Distance Between Faces of Square or Hexagonal) Sections, in.C
						To 1/2, incl	Over ½ to 1, incl	Over 1 to 11/2, incl	Over 11/2 to 2, incl	Over 2 to 21/2, incl	Over 2½ to 3, incl	Over 3 to 31/2, incl
						Thickness of Flat Sections, in.C
HB	HRC			HB	HRC	To 0.3, incl	Over 0.3 to 0.6, incl	Over 0.6 to 1.0, incl	Over 1.0 to 1.3, incl	Over 1.3 to 1.6, incl	Over 1.6 to 2.0, incl	Over 2.0 to 2.3, incl
187 to 293,	91 (Rb)	95 000 to	75 000 to	388	42	1330 8630	8637	3140	4140		4142
incl	to 33,	145 000,	125 000,			4130 50B30		8740	TS4140
	incl	incl	incl			5132			94B40
Over 293	Over 33	Over	Over	409	44	1335	3140 8740	4137 TS4140	81B45	4142	4145	4147
to 341,	to 38,	145 000	125 000			4042 50B30	4135	4140				4337
incl	incl	to	to			5135	4640	8642				9840
		170 000,	150 000,			94B30	8640	8645				86B45
		incl	incl					8742
Over 341	Over 38	Over	Over	455	48	1340 8637	1345 8742	2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard. ASTM Standards A108 Specification for Steel Bar, Carbon and Alloy, Cold-Finished A304 Specification for Carbon and Alloy Steel Bars Subject to End-Quench Hardenability Requirements A311/A311M Specification for Cold-Drawn, Stress-Relieved Carbon Steel Bars Subject to Mechanical Property Requirements A322 Specification for Steel Bars, Alloy, Standard Grades A633/A633M Specification for Normalized High-Strength Low-Alloy Structural Steel Plates A675/A675M Specification for Steel Bars, Carbon, Hot-Wrought, Special Quality, Mechanical Properties Keywords steel bars; Composition analysis--steel materials/applications; Mechanical properties; Selection guides--materials; Steel bars ICS Code ICS Number Code 77.140.60 (Steel bars and rods) DOI: 10.1520/A0400-69R12 ASTM International is a member of CrossRef. ASTM A400 (Steel Standards) Citing ASTM Standards [Back to Top]