April 13, 2021

Austempered Ductile Iron ASTM A897

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, minYield Strength, minElongation, minImpact energyTypical Hardness
A897 Gr. 110/70/11110701180241-302
A897 Gr. 130/90/0913090975269-341
A897 Gr. 150/110/07150110760302-375
A897 Gr. 175/125/04175125445341-444
A897 Gr. 200/155/02200155225388-477
A897 Gr. 230/185/01230185115402-512


Casting Grade

SI units

Tensile Strength, minYield Strength, minElongation in 50mm, minImpact energyTypical Hardness
A897 Gr. 750/500/1175050011110241-302
A897 Gr. 900/650/099006509100269-341
A897 Gr. 1050/750/071050750780302-375
A897 Gr. 1200/850/041200850460341-444
A897 Gr. 1400/1100/0214001100235388-477
A897 Gr. 1600/1300/0116001300120402-512

 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

  1. The graphite component of the microstructure shall consist of a minimum 80% spheroidal graphite conforming to type I and II per ASTM A247
  2. 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)
  3. 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.
  4. 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:

  1. Carbon Equivalent (CE) can be approximated by the relationship: CE=%C+1/3(%Si)
Suggested Carbon Equivalent Ranges for various Section Sizes
Section SizeCE 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
  1. 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
ElementRecommended 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 elementsSuggested 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.

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