Austempered Ductile Iron (ADI) is a ductile iron which is processed by heat treatment of austempering. ADI have very high mechanical property and hardness, but it’s cheaper much than hardened steel www.castingquality.com

Reference Casting Standards: www.castingquality.com
ASTM A897/897M: Standard Specification for Austempered Ductile Iron Castings

ADI castings can be produced in Casting Quality Industrial:

Sand Casting
Shell Casting
Lost Form Casting
gear casting

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Austempered Ductile iron standard grades in ASTM A897

Casting Grade Inch-pound units	Tensile Strength, min	Yield Strength, min	Elongation, min	Impact energy	Typical Hardness
Casting Grade Inch-pound units	Ksi	Ksi	%	Ft-lb	HWB
A897 Gr. 110/70/11	110	70	11	80	241-302
A897 Gr. 130/90/09	130	90	9	75	269-341
A897 Gr. 150/110/07	150	110	7	60	302-375
A897 Gr. 175/125/04	175	125	4	45	341-444
A897 Gr. 200/155/02	200	155	2	25	388-477
A897 Gr. 230/185/01	230	185	1	15	402-512

Casting Grade SI units	Tensile Strength, min	Yield Strength, min	Elongation in 50mm, min	Impact energy	Typical Hardness
Casting Grade SI units	MPa	MPa	%	J	HWB
A897 Gr. 750/500/11	750	500	11	110	241-302
A897 Gr. 900/650/09	900	650	9	100	269-341
A897 Gr. 1050/750/07	1050	750	7	80	302-375
A897 Gr. 1200/850/04	1200	850	4	60	341-444
A897 Gr. 1400/1100/02	1400	1100	2	35	388-477
A897 Gr. 1600/1300/01	1600	1300	1	20	402-512

ASMT A897 Ductile Iron Heat treatment requirement: www.castingquality.com
all castings should be heat treated by an austempering process consisting of heating the castings to a fully austenitic, homogeneous condition or an austenite/ferrite condition for Grade 110/70/11 [750/500/11], cooling (at a rate usually sufficient to avoid the formation of pearlite) to a temperature above the martensite start temperature, and isothermally transforming the matrix structure for a time sufficient to produce the desired properties. This process shall produce a microstructure that is substantially ausferrite or ausferrite/proeutectoid ferrite for Grade 110/70/11[750/500/11].

Microstructure requirement in ASTM A897: www.castingquality.com

The graphite component of the microstructure shall consist of a minimum 80% spheroidal graphite conforming to type I and II per ASTM A247
The matrix microstructure shall ssubstantially consist of ausferrite (acicular ferrite and high carbon, stable austenite). Proeutectoid ferrite will also be present in grade 110/70/11 (750/500/11)
Martensite may be present in minor amounts in the microstructure of Grade 200/155/02 (140/1100/02) and 230/185/01 (1600/1300/01). Acceptable quantities of martensite maybe agreed again.
The microsturcture shall be substantially free of underirable microconstituents.

Chemical Composition in ASTM A897: www.castingquality.com

Chemical requirements may be agreed upon between manufacture, heat treater, and the purchaser. But to achieve the required mechanical property in castings or test coupons, the standard also has some suggestion as below:

Carbon Equivalent (CE) can be approximated by the relationship: CE=%C+1/3(%Si)

Suggested Carbon Equivalent Ranges for various Section Sizes
Section Size	CE Range
0 to 1/2 in. (0 to 13 mm)	4.4 – 4.6
1/2 to 2 in. (13 to 51 mm)	4.3-4.6
Over 2 in. (51mm)	4.3-4.5

Allying elements such as Molybdenum, Copper, Nickel and additional Manganese above the base metal level should be added only when additional hardenability is required for heavy section:

Suggested Targets and Control Ranges for Intentionally Added Elements
Element	Recommended Range
Carbon (C)	3.60% ± 0.20%
Silicon (Si)	2.50% ± 0.20%
Magnesium (Mg)	(%S X 0.76) + 0.025% ± 0.005%
Copper (Cu)	0.80% max, only as needed ± 0.05%
Nickel (Ni)	2.0% max, only as needed ± 0.10%
Molybdenum (Mo)	0.20% max, only as needed ± 0.03%

Suggested Targets and Control Ranges for Trace or Tramp Elements
Trace or Tramp elements	Suggested Target (or maximum)	Typical Contral Range
Tin (Sn)	0.02%, max	± 0.003%
Antimony (Sb)	0.002%, max	±0.0003%
Phosphorus (P)	0.04%, max	–
Sulfur (S)	0.02%, max	–
Oxygen (O)	50 ppm, max	–
Chromium (Cr)	0.10%, max	–
Titanium (Ti)	0.04%, max	–
Vanadium (V)	0.10%, max	–
Aluminum (Al)	0.05%, max	–
Arsenic (As)	0.02%, max	–
Bismuth (Bi)	0.002% max	–
Boron (B)	0.0004%, max	–
Cadmium (Cd)	0.005%, max	–
Lead (Pb)	0.002%, max	–
Selenium (Se)	0.030%, max	–
Tellurium (Te)	0.003%, max	–

Austempered Ductile Iron Castings Application: www.castingquality.com
ADI have high strength and excellent wear resistance property. It’s popular used in
Gear, crankshafts, axles, guide rollers, railway brake shoes, abrasive liners, bearing/bushing sleeves, camshafts, chain sprockets, pulleys, pump impellers, shredder knives and etc.