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CAST IRONS. Advantages and disadvantages of cast irons (in comparison with steels): Advantages : good castability (low T m , good fluidility) good machinability (graphite cast irons) antivibration properties low stress concentration sensibility Disadvantages : high brittleness
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CAST IRONS Advantages and disadvantages of cast irons (in comparison with steels): Advantages : • good castability (low Tm, good fluidility) • good machinability (graphite cast irons) • antivibration properties • low stress concentration • sensibility Disadvantages : • high brittleness • non machinable (white cast iron, chilled cast iron) • cold brittleness (KV = 7 – 14 J, – 40°/+23°C)
CAST IRONS Cast iron structure impactors • Chemical composition (C, Si, Mn) Si graphite cast irons , Mn white cast iron • Cooling rate vjaht white cast iron, chilled cast iron vjaht grey cast iron • Modification Mg, Ts, Ca spheroidal graphite cast iron • Alloying Mn wear resistance Si corrosion resistance Cr high-temperature strength Ni corrosion resistance, with Cr, Si wear resistance
CAST IRONS Structure diagrams of cast irons Chemical composition and cooling rate Chemical composition (C and Si%)
CAST IRONS Classification and properties of cast irons (1) Mechanical properties of main graphite cast irons
CAST IRONS Classification and properties of cast irons (2)
Heat treatment of cast irons (1) CAST IRONS Hardness of metallic ground mass ferrite 100…160 HB pearlite 180…220 HB sorbite 220…300 HB bainite 300…320 HB martensite 380…600 HB Grey cast iron heat treatment
CAST IRONS Heat treatment of cast irons (2) Heat treatment ofspheroidal graphite/ malleable cast iron
CAST IRONS Designation system of cast irons (EN) Designation and materials No. (1) • Grey cast iron EN-GJLL – lamellar G • Spheroidal graphite c.i.EN-GJSS –spheroidal G • Malleable cast iron EN-GJMM –malleable (temper G) • white EN-GJMW • black EN-GJMB Grey cast iron(EN1561) Rm based HB based
CAST IRONS Designation and materials No.(2) Spheroidal graphite cast iron (EN1563) Rm ja A based HB based Malleable cast iron (EN1562) Rm ja A based White Black
CAST IRONS Bainitic cast iron(EN 1564) Designation Material No Application EN-GJS-800-8 EN-JS 1100 Highly stressed parts; wheel hubs, EN-GJS-1400- EN-JS gear rings, ADI castings (austempered ductile cast iron) Vermicular graphite c.i. (ISO 16112) ISO 16112/JV/300 Automotive parts gear housings ISO 16112/JV/500 Wear resistant cast iron(EN 12513) EN-GJN-HV350 EN-GJN-2019 Dressing rolls dredging shovels impellers for pumps
CAST IRONS Cast steels Cast steel for general application (EN 10293) 1) Cast steel for pressure vessels (for high and low temperatures – steam turbines, super heated steam armatures, also corrosion resistant)
Thank You for attention! priit.kulu@ttu.ee