Posted in | Steels

High Strength Engineering Steel - EN24T (817M40T)

EN24T (817M40T) from Thames Stockholders is a bright drawn nickel chromium molybdenum through hardening steel which can be heat treated to create a broad range of strengths. Heat treatment and tempering can both be accomplished with minimum surface scaling. EN24T also profits from wear resistance and good hardenability and is a suitable material for use in the manufacture of punches and dies.


EN24T with its hardenability capabilities is used widely in heavy-duty applications where wear resistance, hardness, and tensile strength are of crucial importance. Delivered in the quenched and tempered or ‘T’ condition, the alloy can be additionally surface hardened up to 60 HRC by flame induction or nitriding processes, which will further improve the material's wear features.

Keep in mind that in the ‘T’ supplied condition, EN24T bars greater than 250 mm in diameter may suffer from lesser mechanical properties when approaching the material’s center. To enhance center core mechanical properties, it is suggested that larger sizes are annealed. Bar and billets supplied in the annealed state also gain from enhanced machinability.

Impact Resistance

Good impact values for EN24T (817M40T) at low service temperatures is another characteristic of this material and for this reason, EN24T has become a widely used material in offshore applications such as in hydraulic bolt tensioners and marine mechanical handling equipment.


Although EN24T is categorized as a readily machinable product, it is harder to machine and use of carbide in the machining process is vital. EN24T (817M40T) can be machined when hardened using stainless tip tools. There is a greater probability of shear loading when compared to other engineering steels such as EN19 and EN16.


EN24T (817M40T) delivers a good combination of hardenability, strength, and wear resistance. Application examples include:

  • Marine mechanical handling equipment
  • Power transmission gears and cams
  • Heavy duty axles
  • Hydraulic bolt tensioners
  • Bolts, shafts, and studs

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