Case Hardening 1.0

Case Hardening 1.0 provides the surface hardness values obtainable after the execution of thermochemical treatments like carburizing, carbonitriding, nitriding and nitrocarburizing for every special alloy and unalloyed structural steel

Description:

Case Hardening 1.0 considers the thermochemical treatments combinations for a given special structural steel, returning the feasibility of the treatment and the possible surface hardness obtainable. The results can be extended even to added Pb or Ca steels (improved workability steels). Even special applications like carbonitriding of some quench and tempering steels or nitriding of spring steels are considered.

Conditions:

1. Austenitic grain dimension 5÷8 according to ASTM E 112-82
2. Absence of overall surface decarburization according to EN ISO 3887:2006, absence of excessive surface work hardening due to coarse mechanical manufacturing or cold plastic deformations
3. Starting heat treatment conditions:
1. Steel subjected to carburizing or carbonitriding:
   ANNEALED or WORKABILITY QUENCHED AND TEMPERED (for the improvement of workability)
2. Steel subjected to nitriding or nitrocarburizing:
   QUENCHED AND TEMPERED (T_tempering > T_{nitriding/nitrocarburizing} + 30°C)

Usefulness:

1. Steel thermochemical treatment choice and optimization during designing
2. Thermochemical treatment inspection during quality control

Caution:

1. For carburizing and carbonitriding the surface hardness obtainable ranges are function of the class of the effective hardening thickness and can be considered valid for the various typologies of the medium-environment (gaseous, liquid, solid, ionic, in vacuum) and for the quenching conditions after cementation (direct, indirect, double, after isothermic preservation)
2. The hardness values have to be interpreted as FINALS (so they provide for possible stress relief tempering treatments and/or below zero treatments)
3. The minimum values of surface hardness obtainable during nitriding and nitrocarburizing strongly depends from: steel chemical composition, starting heat treatment condition, surface condition. The suggested values are considered as PRECAUTIONARY MINIMUM, obtainable in the usual manufacturing experience
4. When the result of the selection is NOT ADVISED TREATMENT means that the performance of the treatment can trigger some metallurgical problems as tempering brittleness, excessive thickness of white layer, excessive tenor of retained austenite

Use:

1. Choose the type of steel that you wish surface harden
2. Choose the thermochemical treatment you wish check if it is feasible for the selected steel
3. Check if the thermochemical treatment is feasible and the possible surface hardness values obtainable

1) Select a steel
Family -- Select a family -- Case-hardening steels Carbonitriding steels Quench and tempering steels Nitriding steels Surface hardening steels Free-cutting steels Bearing steels Spring steels
2) Select a treatment
3) Feasibility check