| Popis: |
The influences of chromium on the stabilization of pearlite in the microstructure of gray iron thin section castings and distortion of castings during enameling were analyzed in this paper. Chromium content varied from 0, 08 wt. % to 0, 37 wt. %. It is found that the distortion of castings with or without the addition of chromium in the as-cast condition was in the acceptable range. The microstructure of castings in as-cast condition was consisted of pearlitic metal matrix and graphite flakes dispersed throughout. The results showed that the distortion of castings containing 0, 08 and 0, 17 wt. % chromium was outside the acceptable range after enameling, due to decomposition of pearlite and transformation to austenite during enameling. After enameling, distortion of castings containing 0, 37 wt. % chromium was acceptable. Decomposition of pearlite was considerably lower than in castings containing 0, 08 wt. % and 0, 17 wt. % chromium. The obtained results confirmed the beneficial effect of chromium on the stabilization of iron carbide and prevention of decomposition of pearlite at elevated temperatures. |
