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Weldability
25CrMo4 is weldable. For optimal results a preheat in the 200°C to 300°C range is recommended. Suitable welding processes include shielded metal arc welding (SMAW), metal inert/active gas welding (MIG/MAG) and tungsten inert gas welding (TIG). A post-weld stress relief (tempering/relief anneal) is recommended to reduce residual stresses.
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Machinability
In the soft-annealed condition the steel machines well; in the hardened condition machining becomes more difficult. Use of cutting fluids is recommended to reduce friction and increase tool life. Tool wear is well-controlled in the annealed state but significantly higher in the hardened condition.
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Magnetic properties
The 25CrMo4 steel is strongly magnetic.
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Forgeability
25CrMo4 has good forgeability. Recommended forging temperatures are between 1100°C and 1200°C. After forging a slow cooling is recommended to avoid stress formation. Normalizing can be applied to refine the microstructure and mechanical properties.
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Corrosion resistance
25CrMo4 has low corrosion resistance. To improve resistance the material is often galvanized (zinc coated). Without surface treatment, highly alloyed steels or stainless steels are better suited for environments with salt water or aggressive chemicals.
