Sinostar MACH has been focusing on ADI-Austempered Ductile Iron technology for more than ten years and is a manufacturer of ADI castings.

Today, we will be learning the international standards of ADI austempered ductile iron based in chronological order: 

1. ISO 17804:2005 

ISO 17804:2005 "Classification of Cast Austempered Ductile Iron" is an ISO standard rather than a standard from a single country. 

This standard specifies the grades and corresponding requirements for austempered ductile iron, and classifies austempered ductile iron based on the mechanical properties measured from machined test pieces. These test pieces may also be made from separate cast samples, cast sample(s), or cut from castings. And it also sets up two levels according to the division of hardness function. 

ISO 17804:2005 has been replaced by ISO 17804:2020, which is the current version. But ISO 17804:2005 still has a certain historical significance and reference value in the foundry industry. 

Introduction to content of the standard 

- Scope: Points out the classification and related requirements of austempered ductile iron. 

- Material grades: clarify the different grades of austempered ductile iron and its characteristics 

- Manufacturing requirements: puts forward requirements on manufacturing process,process control etc of austempered ductile iron 

- tensile and impact properties of casting specimens List the test methods and indicators for tensile properties on casting test pieces. List the test methods and indicators for impact properties on casting test piece. 

- Hardness: To stipulate the hardness standards and testing techniques for austempered ductile iron 

- Casting body specimens: Involve the related ones for sampling and taking the test out of the casting body 

- Graphite morphology: Ductile iron: stipulates the morphological conditions and examination methods for coke in cast iron. 

- Matrix structure: clarify the requirements for the matrix of austempered ductile iron 

- Specimen preparation methods: specification of methods of preparing specimens for making test 

2.ISO 17804:2020

ISO 17804:2020 “Classification of Cast Austempered Ductile Iron” Second Edition was published by ISO. This standard provides the grades of austempered ductile iron and the technical requirements. It is graded according to the tensile properties and hardness of the specimens and suitable to casting materials with iron, carbon and silicon as base elements, carbon basically in the form of spheroidal graphite, and an ausferrite matrix which have been subjected to austempering. 

The ISO 17804:2020 standards emphasize the significance of agreement between supply and demand parties and embody the principles of market economy. Compared with the first edition of ISO 17804:2005 Second Edition revised and supplemented the technical contents, including revising and adding normative references, adding and modifying of the terms and definitions, adding the side by side test blocks, adding the terms for graphite morphology inspection and modifying and enriching Appendix B. 

Introduction to content of the standard 

Update the normative reference document: 

Normative reference documents are updated so that the test methods and associated requirements based on the standard are always the most recent and scientific. as science and technology develop all the time, the test methods as well as corresponding standards keep on improving. Take ISO148 - 1standard for example, updating an existing standard could mean changing test equipment or making improvements to the testing methods. ISO 17804:2020 refers to the updated standard, it can make the austempered ductileiron performance test more correct and reliable, and improve the scientific nature of product quality assessment. 

Improve terms and define words: 

Addition and amendments of the terms, definitions make the standards more correct and complete. The new terms like ausferrite and their explanations make the term library richer for the austenitic iron field, so it becomes easier for people in the same field to communicate and conduct studies. The modified terms make the original definitions correct and clear, they can avoid misunderstanding caused by the vagueness of terms. Like altering the term “ausferrite DUCTILE IRON” probably would provide a more fitting description of the microstructure and function properties of such matter. 

Side by side test block application value: 

Add side by side test blocks gives us more opportunities to test out product performance. Actual production in different test blocks shows the performance of a product under different circumstances. Single cast test blocks can reflect the original performance of the material, attached cast test blocks reflect the degree of proximity to the performance of the casting, side-by-side test blocks can somewhat simulate the actual production of castings, and better reflect the performance of the product. To improve product quality testing and accuracy and reliability by side-by-side test blocks. 

Strengthened graphite morphology checking clause Addition of the graphite shape checking clause, increases the importance of graphite shape for the material. The graph of graphite morphology is one of the important factors influencing the mechanical properties of ductile cast iron. When the addition of inspection clauses, the graphite morphology can be controlled more strictly so as to make sure the qualified performance of products. On the same time, non-destructive can be used testing for inspection, which can make inspection more efficient and convenient and reduce the damage to the products caused by sampling and testing. 

Appendix B content optimization Appendix B, the content of improving the accuracy and reliability of the tensile performance test results through revision and improvement. addition of relevant original specimen with gauge length L0=4 ×d and original specimen with gauge length L 0=5 ×d allows for further testing based on other circumstances. Comparison table of elongation afterfracture and comparison relationship between different original gauge length of specimens make it feasible to compared the test result of the specimen with different original gauge lengths and compared easily the result test of laboratories. 

Appendix G fatigue datasuppplement: 

When adding fatigue info to appendix G to give a way to judge product fatigue performance. fatigue performance is one of the most important performance of material under alternating load For some parts that have to bear loads alternating a long time, like blades of aircrafts, if the fatigue performance of the quality is bad, it will affect the life and security of the service. newly added 5 different test methods fatigue data could have a better way to evaluate the fatigue performance of this product and provide a basis for the design and use of the products. 

Appendix-Other Improvements: 

The content of the spheroidization rate in Appendix H is changed according to ISO945-4; it can evaluate the spheroidization rate accurately and scientifically. spheroidization rate is an important index which can indicate the spheroidization grade of graphite in Ductile iron. And to assess the degree in a more accurate way we get a better evaluation of the material performance. Appendix J adds Chinese GB／T 24733－2009 grade，and revises other foreign standards' grades ，which promote the exchange of international standard grades and improve the international impact of my country's austempered ductile iron casting grades.