Austempering is a specialized heat treatment process used to fortify metals. It amplifies several pre-existing ductile cast iron properties — including strength, abrasion resistance, and toughness.
The result of the austempering process is austempered ductile iron (ADI) castings — aka austenitic ductile castings — are often employed in mission-critical, high-demand applications, for parts that must withstand extreme stresses — in particular the construction and mining, agriculture, automotive, heavy truck, and railroad industries.
OUR AUSTEMPERING PARTNER
Exceptional castings produced from austempering start with exceptional ductile iron.
Urick Foundry's castings are among the industry's highest in graphite nodularity, a key factor in maximizing the austempered ductile iron properties. Applied Process, a world-class expert in metal heat treatments, recognizes this consistency and is proud to work with us as our exclusive austempering partner.
AUSTEMPERING PROCESS
Like other heat treatments for metals, austempering begins by heating a ductile iron part to a temperature of between 1550° and 1700° F, which loosens the molecular structure and allows for increased carbon absorption. Where it differs is the salt quench — immersion of the part in a bath of molten salt (between 450° F to 750° F), rather than oil or water. Because the temperature of the salt bath is held constant over a longer period, carbon absorption and structural consistency are improved as the part cools, resulting in a stronger near-net shape product.
Benefits of Austempering
Lightweight strength
ADI is up to three times stronger than aluminum, and up to 2.3 times as stiff. This means more resilient parts can be achieved with less material, trimming weight from the final product.
Near-net shape products
Other heat treatments can leave metals prone to distortion or cracking as part surfaces and interiors cool at different rates. As an isothermal process, austempering avoids this pitfall.
Cost-effective solution
Per pound, ductile iron parts produced through austempering offer a similar tensile strength to steel with superior yield strength — all in one piece. No additional forging, welding, or fabrication is required.
ASTM A897 / 897M-06 Austempered Ductile Iron Grades
Urick is capable of providing various grades of austempered ductile iron (ADI) castings through a trusted partner, in accordance with the latest standards set forth by ASTM International.
| Prior Designation | Grade |
Tensile Strength (MPa/KSI) |
Yield Strength (MPa/KSI) |
Elongation (%) |
Impact Energy (J/Lb-Ft.) |
Typical Hardness BHN |
| 1 | 900-650-09 | 900/130 | 650/90 | 9 | 100/75 | 269-341 |
| 2 | 1050-750-07 | 1050/150 | 750/110 | 7 | 80/60 | 302-375 |
| 3 | 1200-850-04 | 1200/175 | 850/125 | 4 | 60/45 | 341-444 |
| 4 | 1400-1100-02 | 1400/200 | 1100/155 | 2 | 35/25 | 388-477 |
| 5 | 1600-1300-01 | 1600/230 | 1300/185 | 1 | 20/15 | 402-512 |
Austempering FAQ
What am I getting with a higher grade of austempered ductile iron?
How long does the austempering process take?
Can I machine an austempered ductile iron part?
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