PENGARUH KARBURISING PADA TUNGKU ARANG TERHADAP KETAHANAN EROSI PADA SUDU TURBIN CROSS FLOW T-14

Abstract

       This research was aimed to know the influence of carbureting on the T-14 cross flow turbine blades against the change of their micro structure and erosion resistance.  The tested material of the blades was the St-37 low carbon steel.

       The heat treatment in use were carbureting and quenching.  The used carbureter media was 192 grams of charcoal, 66.5 grams of Sodium Carnate (Na₂CO₃) and 8 grams of Calcium Carbonate (CaCO₃).  The specimens were heated on a charcoal stove at 900^oC in 3 hours and later on it was cooled down in 24 hours of outside temperature.   Some of the carbureted specimens were quenched at 30^oC, increased to 900^oC in 90 minutes, stayed on the same temperature of  900 ^oC in 30 minutes and then they were rapidly cooled  down  in water (H₂O) media. A strech test  was carried on an erosion test machine using  the IPAL Sewon manufacturing water sprayer containing 28 mg/l, 83 mg/l, 815 mg/l of TSS  of which  water spraying  velocity was 10.33 m/s in 40 hours.

       The results showed  an increase the surface hardness of  the carbureted blades of 131% and of the carbureted quenched blades of 332%, compared with  the raw material of blades with hardness of 122.26 kg/mm².  The  hardness of carbureted blades were  283 kg/mm²,  that of the carbureted quenched blades were 528 kg/mm².   It was evident that the carbureted turbin blade and  the carbureted quenched blades had  no erosion influence ,  the erosion rate = 0.000 gram/minute. Specimens made of raw material, the  largest erosion rate = 7.5x10^-6 gram/ minute in sprayed with IPAL Sewon manufacturing water containing 815 mg/l of TSS and for the specimens normalized at 600^oC, the largest erosion rate = 9.16x10^-6 gram/minute in the sprayed with the IPAL Sewon manufacturing water containing  28 mg/l of TSS.