Hardening
The recommended hardening temperature for 80CrV2 is 840–870°C according to standard EN10132. The soaking time depends on whether you harden stock removal or forged blades.
Stock removal blades are ground from steel material that is soft-annealed in a steel factory. The material is intended to be hardened as is. Soft-annealed carbides are relatively large, and Cr slows their dissolution. Therefore, stock removal blades need about 10 minutes of soaking after the blade attains the hardening temperature. Forged blades have smaller carbides that readily dissolve when a blade attains hardening temperature; no soaking time is needed.
The total furnace time (heating+soaking) depends on the furnace, blade size, and steel microstructure. If the time is too short, insufficient carbon dissolves, and the blade does not achieve high hardness, while too long a time results in a deep decarburized surface layer and a thick oxide scale. It is better to use a longer furnace time than a shorter one. Usually, 20 minutes does the job.
Quench the blade in oil, as quenching in water will result in cracking. Warm canola oil (about 70°C) works well. The as-quenched hardness is about 66 HRC.
Tempering
Temper the blade immediately once it has cooled to room temperature, as waiting too long may result in the cracking of untempered martensite. The best combination of hardness and toughness is achieved when the blade is tempered at 170–180°C for 1–2 hours, which produces a hardness of about 63 HRC.