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ASTM A897 Grade 3 175-125-04 ISO 17804, EN-1564

Posted by Penticton Foundry on December 4, 2023

Railroad repair cart wheels made in ASTM A897 Grade 3 175 – 125 – 04 austempered ductile iron.

Austempered ductile iron (ADI) is an alloyed ductile iron that is heat treated by an austempering process. This austempering process includes heating the casting to a fully ferritic, homogenous condition and then cooling it to a controlled temperature above the martensitic start temperature. This isothermally transforms the matrix structure to achieve the desired properties.

ASTM A897 175-125-04 is one of 6 grades of ADI. It can be used as an alternative to steel forgings, providing cost savings with high strength and abrasion resistance.

Case Study: Read this case study on an innovative use of chrome white iron and austempered ductile iron to solve a mine’s challenge with a gyratory crusher liner.

Composition

Chemical composition is not specified in the ASTM A897 175-125-04 specification, but below is an example of chemistry ranges. The heat treater would also specify some elements like Cu, Ni, and Mo for improved heat treatment.

CMnSiCrNiCuMoMg
Min%3.302.300.025
Max%3.70.352.70.060.055

Physical and Mechanical Properties

UTS (psi)175000
TS (psi)125000
% Elongation4
Typical Hardness (BHN)341-444
Density (lb/in^3)0.256
Thermal Conductivity (BTU/hr-ft-F)149
Coefficient Thermal Expansion7.8
Melting Temperature (F)2100
Compressive Strength (Ksi)280

Impact Properties

Un-notched Charpy impacts at 70F = 70 ft-lb
Notched Charpy impacts at 70 F = 7 ft-lb

Austempered Ductile Iron (ADI) Design Benefits

When deciding when to use ADI consider the following:

  • ADI is lower cost, and has greater design flexibility than forgings because it is a cast product
  • ADI has a greater strength-to-weight ratio than steel
  • If you compare ADI to the same dimensions of steel it is lighter because it is 10% less dense1
  • ADI yield strength is over 3x that of cast or forged aluminum, and only weighs 2.4 times more, while being 2.3 times stiffer2
  • ADI has better wear resistance than conventional ductile iron grades
  • ADI is machinable before or after the austempering heat treatment
  • ADI has greater toughness than convention ductile irons, and has equivalent or better toughness than most cast or forged steels3

Pro Tip: All of the properties above are strongly dependent on the microstructure of the ADI. Therefore choosing the correct grade is important for your application.

Applications

  • Grates
  • Mining parts like liners and concaves
  • Cart Wheels
  • Gears
  • CV Joints
  • Sprockets
  • Suspension brackets and housings
  • Hitches

Reference

[1] “Section 4: Austempered Ductile Iron,” in Ductile Iron Data for Design Engineers, Montreal, Quebec: Rio Tinto Iron & Titanium Inc, 1990
[2] “Section 4: Austempered Ductile Iron,” in Ductile Iron Data for Design Engineers, Montreal, Quebec: Rio Tinto Iron & Titanium Inc, 1990
[3] “Section 4: Austempered Ductile Iron,” in Ductile Iron Data for Design Engineers, Montreal, Quebec: Rio Tinto Iron & Titanium Inc, 1990



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