1.1191 | C45E +QW Hardened at too low temperature

This hypoeutectoid steel (bar stock with ⌀ = 30 mm) with 0.43% carbon (measured by OES; target: 0.42-0.5%) was austenitized at 750 °C for 30 min and then quenched in water.  The austenitizing temperature was too low (target: 820 – 860 °C), annealing was performed between Ac1 and Ac3 instead of above Ac3. Due to the relatively low carbon content, annealing in the upper range of the temperature range would be reasonable (about 50 °C above Ac3, line G-S in the metastable iron-carbon diagram).  The microstructure consists both at the rim entirely of ferrite (rim decarburization), with increasing distance also martensite and fine-grained pearlite (troostite) form. The microstructure in the core thus also consists of ferrite, tempered (cubic) martensite and fine-striped pearlite. Due to the soft ferrite still present, this is also referred to as soft-spottedness.

The average core hardness is 285 HV5 (quite low, due to the low martensite and high ferrite content).