Hot Work Tool Steel

Generally the term 'hot work steels' includes tool steels which adopt a constant temperature about 200°C during application. Consequently, hot work applications involve the usual stresses which tool steels are subjected to, plus thermal stresses due to the contact between tools and hot materials during forming.

Hot work steels must exhibit good heat checking resistance in order to delay the formation of thermal fatigue cracks appearing on the surface as a consequence of frequent temperature changes in the surface region. The cleanliness of the steel is a deciding factor for a long tool life and for resistance to heat checking. To avoid hot cracks, i.e. tension cracks developing primarily in tools with deep cavities at sectional transitions and edges, hot work steels have to feature good high temperature toughness.

For tools subjected to high impact, pressure or tensile stresses at elevated temperatures, special attention must be paid to high strength at the various working temperatures. If the structural state is changed by the influence of heat, the strength at ambient temperature and consequently the strength at working temperature are reduced. This is why good high temperature strength and superior retention of hardness are prerequisites for stability of shape.

Excellent high temperature wear resistance is necessary for ensuring satisfactory tool life.

Further demands that must be met by hot work steels are low tendency to adhere to parts being processed, high resistance to erosion, high temperature corrosion and oxidation, dimensional stability during heat treatment and good machinability.

Typical areas of application for hot work tool steels are pressure casting, extruding, drop forging, pipe and tube production and in the technical high performance manufacturing of specialised glass products.

Bohler ---- ISODISC
Special heat treatment.

Bohler ---- ISOBLOC
ESR quality.

Bohler ---- VMR
Vacuum melted, remelted quality.