1.2738 (40CrMnNiMo8-6-4) Material Data Sheet

The steel 1.2738 is an alloyed, tempered tool steel and is characterized by a high level of hardenability through larger wall thickness cross-sections (over 400 mm) and good hardenability up to over 52 HRC. The small amount of alloy of the elements molybdenum and nickel improves the temper resistance and reduces the sensitivity to temper embrittlement.

1.2738 Steel can be surface polished, but is not suitable for welding.

Field of application

The steel with the material number 1.2738 is used for components in plastic mold construction and is also frequently used in the automotive supply industry and in plant construction. The material 1.2738 is used for large molds and zinc die-casting molds. It can also be used as a further development and improvement of the material 1.2311 (40CrMnMo7), through alloy additions and corresponding heat treatment as the basis for mechanical finishing.
 

Brinell hardness:
300-370 HBW (Rm approx. 1000-1220 MPa)

Soft annealing: The steel 1.2738 is soft annealed at 710°C - 740°C. This is followed by slow (oven) cooling. A maximum annealing hardness of 235 HB (21.7 HRC / 247HV) is achieved.

Hardening: The hardening process takes place at 840°C - 870°C and is carried out in oil / polymer.

Tempering: The material number 1.2738 is tempered at 500°C - 650°C with subsequent cooling in the air.

Relaxation: Due to changes in the residual stress state due to the mechanical processing, a subsequent stress relieving in the temperature range of 500-550 ° C is recommended.
 

Special features:

• Very high temperability (even in large wall thickness ranges)

• Good machining properties with grain-suitable, polishable surface finish

Physical Properties:

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The processing with the saw is a mechanical processing of the material, which results in a significantly lower unintended deformation and increased hardness for the existing structure, such as the thermal cutting.

Thus, the machined workpiece has a homogeneous structure even at the edge, which does not change in the continuation of the material.

This circumstance allows immediate finishing of the workpiece with milling or drilling . So it is not necessary to anneal the material or make a similar operation beforehand.