This specification defines the requirements for locally hardening steel parts by the induction hardening method. Application This procedure has been used typically to harden local areas of parts without heating the entire part to hardening temperatures or to harden a local area of a part to a higher hardness than surrounding areas for increased wear or strength@ often at the expense of other characteristics such as toughness@ but usage is not limited to such applications. Classification Induction hardened parts are classified as follows: Class 1 - High Integrity or Critical Class 2 - Structural Quality Class 3 - Wear Resistance When a class is not specified@ Class 2 shall be supplied.