EN24

EN24 Grade Introduction:

EN24 Alloy Steel is a very high-strength steel alloy that is supplied hardened and tempered. The grade is a nickel-chromium molybdenum combination – this offers high tensile steel strength, with good ductility and wear resistance characteristics. With relatively good impact properties at low temperatures, EN24 is also suitable for a variety of elevated temperature applications. EN24 sections larger than 250mm may still be available in the quenched and tempered condition, but it should be noted that a fall-off in mechanical properties may be apparent approaching the center of the bar. It is therefore recommended that larger sizes are supplied in the annealed (softened) condition and that quenching and tempering are carried out after initial stock removal. This should achieve better mechanical properties towards the core.

EN24 Grade Application:

  • High strength shafts
  • Punches & dies
  • Drill bushings
  • Retaining rings
  • Gears

EN24 Equivalent Grades:

Standard Specification
BS 970:1955 EN24T
BS 970:1991 817M40T
German / DIN 34CrNiMo6
French AFNOR 35NCD6
American AISI / SAE 4340
German Werkstoff No. 1.6582
European Standard EN10277-5

EN24 Chemical Composition:

Element C Si Mn P S Cr Mo Ni
Content (%) 0.36-0.44 0.10-0.35 0.45-0.70 0.035 Max 0.040 Max 1.00-1.40 0.20-0.35 1.30-1.70

Mechanical Properties:

Condition Tensile N/mm² Yield N/mm² Elongation % Izod KCV J Hardness Brinell
T 850-1000 650 13 35 248-302
U 925-1000 755 12 42 269-331
V 1000-1150 850 12 42 293-352
W 1075-1225 940 11 35 311-375
X 1150-1300 1020 10 28 341-401
Y 1225-1375 1095 10 21 363-429
Z 1550 1235 5 9 444

Physical Properties:

Thermal conductivity at °C W/(m*k)
40.5 20
32.5 350
25.5 700

Thermal Properties:

Thermal conductivity 41.9 W/m-°C

Forging Properties:

Preheat carefully, then raise temperature to 1000-1100°C for forging. Do not forge the steel below 850-1100°C. After forging cool slowly preferably in a furnace.

Stress Relieving:

When parts are heavily machined, ground or otherwise subject to cold work, stress relieving will be beneficial prior to hardening. Heat carefully to 650-670°C, soak well before cooling in the furnace or in the air.

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