Abstract
Machined surface and chip formation mechanism in pure iron with a single phase and low C structural steel (S10C) with dual phases is discussed, using the Quick Stop Test (QST). On the machined surfaces, chip surfaces and built-up edges of the QST samples, many elongated dimples are found and the dimples suggested that the fracture occurred on both the rake side and flank side of the tool. These results suggested that the chip, surface and Built-up Edge (BUE) formation of pure iron and S10C are formed by accumulation of many fine ductile fractures. Therefore BUE formation is affected by microstructure, because the ductile fracture property is affected by microstructure of steels.
