Question

1. Observe the microstructure of three given cast irons samples (1, 2 and 3) using optical microscopy and then a) Identify each of them from their key microstructural features from micrograph. b) Specify your reasons for identification and compare their mechanical properties. c) Schematically draw the microstructures and mark all the microstructural features. 100 um Sample 2 100 um Sample

Answer 1

Sample 1 - nodular cast iron or ductile cast iron Sample 2 – Gray cast iron Sample a white cast iron sample 1 – yeypically agok spheroidal nodules & graphite are observed, embedded in ferrite regfon clight area) 11) Based on this reason we. can conclude this is nodular (I Sample 2 - In sample 2 we can observe the graphite flakes are Pearlite region. Based on this we can conclude this is a are present in gray ci. sample 3 In this sample cementite is present in dendrotie form fina dark colour. This cementite dendritics are present in the peastite marie region. Mechanical propertiest Sample 4 sample 2 sample3 nodular cl Gray ci White CL. This nodular cI have Excellent .due to large amounty cementite it is hard & brittle. Poor weldability : Easy to cast, especially . Extremly bolite f Eleellent castability advantageous to large ditticulĚ to macbîne. compler shapes Excellent wear High modulus g Excellent wear Resistance elasticity resistance Excellent damping High compressive properties strength. maximum ductility & machinability machinability -spherical nodules Ferrite cementite Edendrotic graphite Flakes. "form) SI -Nodulare i Epealite. 82 - Gray ci pearlife mabix S3 - klhite el

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