16NiCrS4 is a low-alloy (chrome-nickel) case-hardening steel. Machining of larger components with complex shape, e.g. gear wheels, is facilitated by the steel being soft-annealed after forging to achieve a hardness of 217 HB or below.
16NiCrS4 is standardised in SS-EN ISO 683 - 3. The hardness as supplied corresponds to “+A” (soft annealed). The (discontinued) SS-designation is 2511.
Base hardenability is an important characteristic of case-hardening steels since it determines core properties after hardening and tempering. It is normally specified in terms of a Jominy diagram, which gives the hardness distribution as read off on a sample which has been hardened by directing a spray of water at its one end according to a standardised procedure. The addendum “+HL” after the steel name signifies that the analysis is controlled such that the Jominy curve lies between limits which are stipulated in the SS-EN ISO 683 - 3 standard.
Tibnor’s stock standard programme encompasses forged bars of steel 16NiCrS4 in rough-turned execution. The diameter tolerance is then +3/-0 mm.
The low carbon level in 16NiCrS4 means that weldability is quite good but even so, pre-heating will normally be necessary. Thanks to the low hardness and soft-annealed microstructure, machinability is excellent.