ADI & IDI Austempered Ductile Iron and Perferritic Isothermal Ductile Iron. Industrial Vehicles components

Transcription

1 ADI & IDI Austempered Ductile Iron and Perferritic Isothermal Ductile Iron Industrial Vehicles components

2 ADI: Austempered Ductile Iron Austempered ductile cast irons are spheroidal graphite cast irons which combine higher strength and toughness properties as the result of a special heat treatment. This heat treatment, which is an integral part of the production process, consists of an austenitizing treatment at a temperature between 820 C and 950 C and an austempering treatment in the tempe rature range between 250 C and 400 C to form a predominantly austeni tic-ferritic structure. Depending on casting thickness and required material grade, some alloying elements such as Ni, Mo, Cu are added to the basic chemical analysis.

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5 Lightness Being the specific weight of ADI the same as cast iron (7,1 Kg/dm^3), a real, immediate saving of about 10% weight compared to steel is possible, through keeping the same geometry of the component. More complex and more compacted shapes More complex and more compacted shapes The casting technology of ADI is the same as the one of conventional cast irons. Cast irons show a lower shrinkage tendency and a higher range between melting and solidification temperature compared to casted steel. Those two characteristics allow to gain quality parts even in presence of complex geometries. Moreover, this capability give more freedom to the designers, in order to design components with high mechanical performances in one unique casting instead of several welded parts, avoiding this way welding operation, and obtaining a part with no weak points due to material discontinuity.

6 Noise reduction The presence of graphite and the ausferritic structure have a vibrationdamping effect, with the desirable result of an overall noise reduction. Wear resistance The ausferritic structure gives the material a high wear resistance, which allows to avoid treatments like surface induction hardening. The wear resistance is the same through the entire thickness on the part, and not only on a superficial layer.

7 IDI: Perferritic Isothermal Ductile Iron Isothermal Ductile Iron (IDI) is produced by heat-treating an unalloyed ductile iron, casted with a special preconditioning of the metal bath. IDI is a new intermediate grade between ADI and pearlitic ductile iron. Zanardi Standard 101:2007. Perferritic Spheroidal graphite cast iron Cast material, iron and carbon based, carbon being present mainly in the form of spheroidal graphite particles, subjected to an isothermal heat treatment in order to produce a Perferritic Matrix. Graphite spheroidizing treatment Process which brings the liquid iron into contact with a substance to produce graphite in spheroidal form during solidification.

8 IDI: Perferritic Isothermal Ductile Iron Isothermal heat treatment of spheroidal graphite cast iron Process, consisting of heating the casting above the Ac1 (temperature at which austenite starts to form during heating), cooling at a rate able to promote the formation of pearlite, and transforming the matrix structure for a time and a temperature (above the martensite start temperature) sufficient to produce the desired properties. This process produces a microstructure that consists predominantly of interconnected ferrite and pearlite. This microstructure, when obtained by an isothermal heat treatment, is called Perferritite.

9 IDI: Mechanical Properties Minimun Zanardi Values IDI Minimum Values Material designation JS/700-2/S ISO1083:2004 GH75/45/ IDI/S ZND101:2007 GGG70BA/S JS/800-10/S ISO17804:2005 Relevant wall thickness T R m (min) R p0.2 (min) A 5 (min) HBW +23 C -20 C -40 C mm N/mm² N/mm² % J J J Tensile strength ,2% Proof strength Elongation 2 5 * Brinell Hardness Range Typical impact resistance values (27) (125) (10) (110) (8) (104)

10 IDI: Perferritic Isothermal Ductile Iron

11 IDI: Perferritic Isothermal Ductile Iron Good static properties IDI has shown Fatigue = Pearlitic DIs Machinability Pearlitic DIs Impact > Pearlitic DIs

12 Mechanical Properties Minimum Values (ISO 17804) Material Designation Wall Thickn. Rm R P0.2 A5 HB IDI ZANARDI STD 101:2007 (TENTATIVE SPECIFICATION) 30 < t < t ADI 800 ISO 17804/JS/ < t < t ADI 1050 ISO 17804/JS/ < t < t ADI 1200 ISO 17804/JS/ < t < t Properties measured on test probes machined from separately cast or cast-on samples

13 Mechanical Properties Typical Values Zanardi Material Designation Wall Thickn. Rm R P0.2 A5 HB IDI ZANARDI STD 101: < t < t ADI 800 ISO 17804/JS/ ADI 1050 ISO 17804/JS/ ADI 1200 ISO 17804/JS/ Properties measured on test probes machined from separately cast or cast-on samples

14 Spring Seat Off-Road Vehicles Previous technology: Quench & temper Perlitic ductile iron Potential development: ISO 17804/JS/ (increase of wear) Advantages Wear resistance Standard Material ADI Delivery conditions Weight: kg Painted and Machined

15 Spring Seat Off-Road Vehicles

16 Suspension Arm Off-Road Vehicles Production started on 1987 Previous technology: steel welded / assembled parts Potential development: IDI (Alloyings( cost reduction). Advantages Cost savings; one rigid piece Standard Material ADI ; IDI Delivery conditions Weight: kg Painted

17 Suspension arms for coaches Previous technology: Steel casting or Ductile Iron Casting Advantages Cost savings Lightness Narrower thicknesses than DI Standard Material ADI Delivery conditions Weight: 33 kg Painted

18 Suspension arms for buses Standard Material ADI Delivery conditions Weight: 40kg Painted

19 Suspension arms Standard Material ADI Delivery conditions Weight: kg Painted

20 Steering Knuckles Applications: Bus; Agri Tractors; Off-Road In substitution of forged steel or steel casting Advantages Weight reduction Reduction of machining operations No need surface hardening after machining Standard Material ADI Delivery conditions Weight: kg Painted

21 Steerable stub axle IDI Potential applications Advantages Weight & Cost reduction Reduction of machining operations Standard Material Forged Steel