Effect of casting design to microstructure and mechanical properties of 2 MM TWDI plate

It is important to strictly maintain the cooling rate in producing thin wall ductile iron (TWDI) to prevent carbide formation. There are many ways to control cooling rate whereas casting design is the most independent one. This paper discusses the effect of gating system design on microstructure and mechanical properties of 2 mm TWDI plate. A casting design based on vertical gating system is made to produce TWDI plates with the thickness of 1, 2, 3, 4, and 5 mm. This vertical system allows plates to function as runner. This situation helps in preventing premature solidification. There are three designs in which they are coded as T1, T2, and T3. These three designs were also used in making 1, 3, and 5 mm TWDI plates of which the result has been published. Z-Cast is used to conduct a casting design simulation for filling flow and solidification. The result of flow simulation shows that the filling flow is resulted in two kinds. The result of solidification specifies that in T1 and T2 the 2 mm TWDI plates solidify in the same time as 1 mm TWDI plate. Furan sand was used as moulds in the experiment. The result of the experiment highlights that in all of the designs, which have microstructure and consisted of nodule graphite in ferrite matrix, no trace of carbide and skin effect are formed. The length of skin effect varies in all of the designs. The highest nodularity is only 86% while nodule count is 1344 nodules/mm2. Brinell hardness number for all of the design is beyond the standard given by JIG G5502. As for UTS and elongation none of the designs exceeds the minimal standard. The result of the experiment does not confirm the result of the simulation. In sum, compared to the previous result, the curve trends of 2 mm TWDI plate combine the curve trends of 1 and 3 mm TWDI plates.