This standard specifies the technical requirements and corresponding examination methods for metallographic examination of induction hardened steel parts.
It is applicable to the examination of metallographic structure and effective depth of hardening of mechanical parts made of medium-carbon structural steels and medium-carbon alloy steels after high- and medium-frequency induction hardening.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections) to, 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 undated references, the latest edition of the normative document referred to applies.
GB/T 5617 Determination of effective depth of hardening after induction or flame hardening of steel (GB/T 5617-2005, ISO 3754:1976, NEQ)
3 Technical requirements
3.1 The surface hardness and effective depth of hardening of parts shall meet the requirements of the product drawing.
3.2 After quenching, the parts shall be free from defects such as cracks and burns on the surface.
3.3 After quenching and low temperature tempering (≤200℃), the parts shall be subjected to metallographic structure evaluation according to Figure 1, a) to j). See Table 1 for the grading description.
Where the drawing specifies that the lower limit of hardness is higher than or equal to 55HRC, Grade 3 to Grade 7 are acceptable.
Where the drawing specifies that the lower limit of hardness is lower than 55HRC, Grade 3 to Grade 9 are acceptable.
