1.2067 | 102Cr6 +QO +T Sub-heat hardened and tempered

This hypereutectoid steel (bar stock with ⌀ = 16 mm) was austenitised at 740 °C for 30 min, quenched in oil and then tempered at 180 °C for 2  hours. The austenitisation temperature was too low (target: 830 – 850 °C). The microstructure consists of tempered (cubic) martensite, pearlite and ferrite with moulded cementite and chromium carbides (soft annealing microstructure). In part, (former) cementite lamellae of the pearlite can still be guessed at in the martensite (lamellar underground structure; see circle marking on the last picture). It was therefore not completely austenitised (only to approx. 95 %; due to too low a temperature), no through-hardening to the core has taken place. If austenitisation had  proceeded correctly and the fault was in the quenching rate, the structure would have to consist entirely of bainite and/or pearlite.