Metallographic examination of pearlitic graphite cast iron parts induction hardened
1 Scope
This standard specifies the technical requirements and corresponding method for metallographic examination of pearlitic graphite cast iron parts induction hardened. It is applicable to the examination of the metallographic structure and depth of the hardened layer of the graphite cast iron parts having a pearlite volume coefficient of not less than 75%, which have passed high and medium frequency induction hardening and low temperature tempering (with tempering temperature ≤200℃).
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), or revisions, of any of these publications do not apply to this standard. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition applies.
GB/T 7232 Terminology of metal heat treatment
3 Terms and definitions
For the purposes of this standard, the terms and definitions given in GB/T 7232, as well as the following apply.
3.1
delimitation microstructure
delimitation structure with area fraction of pearlite as 20%; in special circumstances, other delimitation structures may be adopted through negotiation between the parties concerned
4 Technical requirements
4.1 The surface hardness and hardened layer depth of parts shall meet the requirements of the product drawing.
4.2 After being subjected to induction hardening at high and medium frequency , the surfaces of parts shall be free of defects such as hardening cracks and burns.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Technical requirements
5 Preparation of specimens
6 Examination method
Figure 1 Rating of pearlitic graphite cast iron parts induction hardened (×400)
Figure 2 Standard drawing for measurement of hardened layer depth (×100)
Table 1 Description of microstructure classification of hardened layer
