This Standard specifies the structural steels with specified hardenability bands
(hereafter referred to as "steels"), which are manufactured by hot forming such as
hot rolling and hot forging, and mainly used for machine structural use. This steel is
normally used after further forming such as forging and cutting and heat treatment.
NOTE : The International Standards corresponding to this Standard are as fol-
lows.
ISO 683-1 : 1987 Heat-treatable steels, alloy steels and free-cutting
steels w Part 1: Direct-hardening unalloyed and low-alloyed wrought
steel in form of different black products
ISO 683-11 : 1987 Heat-treatable steels, alloy steels and free-cutting
steels m Part 11: Wrought case-hardening steels (overall evaluation :
MOD)
In addition, symbols which denote the degree of correspondence in
the contents between the relevant International Standards and JIS are
IDT (identical), MOD (modified), and NEQ (not equivalent) according
to ISO/IEC Guide 21.