1.1191 | C45E +QW +T Overheated hardened and tempered

This hypoeutectoid steel (bar stock with ⌀ = 30 mm) with 0.43 % carbon (measured by OES; nominal: 0.42 – 0.5 %) was austenitized at 900 °C for 30 min, quenched in water and then tempered at 250 °C for 2 hours. The austenitizing temperature is above the temperature intended for this material (820 – 860 °C). The microstructure consists in the core of pearlite and ferrite, which forms an almost continuous network and partly occurs in Widmannstättenscher arrangement. Approximately 90% pearlite and only 10% ferrite are present, as the pre-eutectoid ferrite formation was still suppressed. Directly at the rim the microstructure is completely martensitic (tempered, cubic martensite) . Only with increasing edge distance, from approx. 3 mm onwards, the formation of fine-striped pearlite (troostite) begins, further away also then the ferrite formation. C45 is a case hardener: due to the lack of alloying elements, the microstructure in the core does not completely transform into martensite.

The core hardness is 306 HV5.