Description / Abstract: This specification details the material characteristics of three grades of oil hardened and tempered chrome silicon round steel wire used in the manufacture of springs for both static and dynamic applications involving moderately elevated temperature and medium-to-high stress. Spring manufacturing and performance requirements are also included. Note that Grade A is no longer applicable to this standard.

Material Description. Unless otherwise specified, the wire shall be drawn, austenitized, oil quenched and tempered to conform to the mechanical property limits shown in Table A1. The three grades are distinguished by their respective limits for decarburization and seam depth and by the range of mechanical properties shown in Table A1. A reference of replaced/comparable grades is given in Section 9.

Grade B. Exhibits the lowest range of mechanical properties, and is the only Grade of wire with two Classes of temper condition (hardness) for finished springs.

Grade C. Decarburization limits are more restrictive than B.

Grade D. Allowable seam depth is shallowest of the three Grades. Most restrictive decarburization limits and generally highest yield strength of the three grades.

Symbols. Not applicable.

Applicability. Applications include but are not limited to oil pump relief springs, compression springs used in tensioner assemblies, piston pin retaining clips, and automatic transmission valve body control springs and shifting piston return springs.

Remarks. When specifying one of the material Grades it is recommended that a tensile strength and/or equivalent hardness be referenced on the Engineering drawing. The words “Class 1” or “Class 2” should be used with Grade B wire to designate spring hardness.