This standard defines the carburized and carbonitrided case-hardened depth, and specifies methods for the determination of this depth, in steel.
It is applicable to carburized cases and carbonitrided cases; parts that, when heat treated to final hardness, have a hardness of less than 450 HV at a distance of three times the case-hardened depth, from the surface.
The case-hardened depth is defined by special agreement where these conditions are not met.
For steels that, in the part under test, and at a distance of three times the case-hardened depth from the surface, present a hardness greater than 450 HV, the criterion can still be used, provided that a limiting hardness value greater than 550 HV—in steps of 25 units—be selected for the case-hardened depth.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding any corrigendum), or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For any undated references, the latest edition of the document referred to applies.
GB/T 4340.1 Metallic materials—Vickers hardness test—Part 1: Test method
GB/T 18449.1 Metallic Knoop hardness test—Part 1: Test method
3 Terms and definitions
For the purposes of this standard, the following term and definition applies.
Case-hardened depth (of a carburized and hardened case)
Perpendicular distance between the surface and the layer having a Vickers hardness of 550 HV1 in accordance with GB/T 4340.1 or GB/T 18449.1
