Nanocarbides II – Influence of deep cryogenic treatment on distortion, corrosion and fracture toughness

Initial Position / Aims:

In a previous project, high-alloy steels from the hot work, cold work and plastic moulding sectors were subjected to an adapted heat treatment, integrating a cryogenic treatment into the steps of austenitising, quenching and tempering in such a way that a comparable hardness was achieved during hardening and tempering or hardening, cryogenic cooling and tempering. Main effects of deep cooling are the reduction of the residual austenite content already during cooling and the precipitation of finer secondary carbides during tempering for the higher carbon alloyed steels.
Three aspects have not yet been investigated. One is shape changes that occur during hardening and tempering. The integration of a cryogenic treatment can lead to improved dimensional stability. Due to the altered shape changes when using cryogenic treatment, it can be assumed that the residual stress states in the quenched and tempered state will change. These can influence the tendency to hydrogen embrittlement.
In addition, the occurrence of fine, homogeneously distributed secondary carbides during tempering could be increased by the cryogenic treatment. Within the framework of this project, the corrosion behaviour when using cryogenic treatment will be also investigated.

Results:

Influence of fine, homogeneously distributed secondary carbides on distortion, corrosion and fracture toughness.

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