SAE J434 for Automotive Ductile (Nodular) Iron Castings

The SAE standard covers the minimum mechanical properties measured on separately cast test pieces of varying thickness and micro-structural requirements for ductile iron castings used in automotive and allied industries. Castings may be specified in the as-cast or heat –treated condition. If castings are heat-treated, prior approval from the customer is required.

1 Grades

The grades, mechanical properties and metallurgical description are shown in Table 1.

Table 1 Grades of ductile iron

Please refer to ISO 6506/ASTM E 10 for Brinell Hardness of Metallic Materials Casting properties and microstructure may vary due to chemistry, section size/cooling rate and other parameters. It is desired that separately cast test bars reflect properties of the castings they represent. Casting process for separately cast test pieces shall be agreed upon between manufacturer and purchaser. Refer to ASTM A536.

2. Hardness
The hardness ranges shown in Table 1 are for guidelines only.

The area or areas on the castings where hardness is to be checked should be established by agreement between manufacturer and purchaser.

3. Heat Treatment

4.1 The heat treatment of castings and test specimens produced to this standard in order to meet hardness or other mechanical property requirements, for thermal stress relief or for other purposes is permissible only with the express approval of the casting purchaser.

4.2 Purchaser approval may be blanket or may be issued on a case-by-case basis, as agreed.

4. Microstructure

The graphite component of the microstructure shall consist of at least 80% spheroidal graphite conforming to Types Ⅰand Ⅱ(per ASTM A247) in Fig. 1 (nodularity rating chart developed by the Ductile Iron Society may be used as a guide). The matrix microstructure shall consist of ferrite, ferrite and pearlite, pearlite, tempered pearlite, or tempered martensite, or a combination of these.

Table A2 Charpy un-notched impact energy

Properties are obtained from separately cast test bars tested @22C+/-2C (72F+/-4F).
For details of Charpy Test, please refer to ASTM Impact Text (ASTME 23)

5. Typical applications

D400 (D4018) is used in moderately stressed parts requiring high ductility and good machinability.
D450 (D4512) is used for moderately stressed parts where machinability is less important.
D500 (D5006) is used for moderately stressed parts where machinability is less important.
D550 (D5504) is used for more highly stressed parts.
D700 (D7003) is used where high strength and/or improved wear resistance are required and where selective hardening is to be employed.
D800 is used where high strength and/or improved wear resistance are required and where selective hardenings is to be employed.
DQ&T is used where the uniformity of a heat –treated material is required to control the range of mechanical properties of machinbility.

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