In making thin wall ductile iron problems occur due to the failure of molten metal treatments and the formation of carbides. Researchers believe that the carbon equivalent plays an important role. This research has been conducted to see the effects of carbon equivalent on the microstructure of thin wall ductile iron especially on the formation of carbides. Several pouring were taken to gain varied the carbon equivalent (CE) values. Chemical compositions were examined before the liquid treatment by using spectrometry. The observations made were carbides appearance, nodule count, nodularity and nodule diameter uniformity. The calculation of nodular graphite characteristic were made by using manual calculation based on American Standard Testing Material (ASTM) A427 and also by using Cyuuzou Kun and NIS Element Softwares. Cyuuzou Kun is an imagine analysis software used in Iwate University, while NIS
Element is an imagine analysis software built by Nikon. The result is that the carbon equivalent itself does not affect the formation of carbides but it does affect the nodularity.
Due to the need for light weight materials to reduce energy consumption, aluminum has been chosen more than ductile iron in the automotive industry. In fact, apart from the weight problem, ductile iron has more advantages than aluminum. One of the advantages of ductile iron is the lower production cost. To make it possible for ductile iron to compete in terms of weight, thin walled ductile iron is produced. The standard of casting thickness classified as thin wall ductile iron casting (TWDI) has not been established yet.