EN 24

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					                                            EN 24 Material
EN24 is a popular grade of through-hardening alloy steel due to its excellent machinability in the "T" condition.
EN24T is used in components such as gears, shafts, studs and bolts. EN24T can be further surface-hardened to
create components with enhanced wear resistance by induction or nitriding processing.

International Steel Specification Comparison (EN24T)
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
Typical chemical composition of En24
      C             SI            MN            S              P              Cr              Mo                 Ni
  0.36/0.44     0.10/0.35      0.45/0.70   0.040 max       0.035 max       1.00/1.40       0.20/0.35          1.30/1.70

Used in construction of aircrafts and heavy vehicle for crankshaft, gearshaft, camshaft, propellershaft etc
Carbon(C) Directly influences the hardness and strength of the steel, decreases toughness.
Chromiun(Cr) Improves Hardenability, high temperature strength, wear resisitance and even corrosion
resistance(Cr>14%).
Cobalt(Co) Improves retention of hardness at high temperatures.
Molybdenum(Mo) Increases yield point and strength. Improves Hardenability and wear resistance. Manganese
Lowers effects of Iron sulphides, increases hardenability, wear resistance.
Nickel(Ni) Increases toughness at lower temperatures, slows the corrosion process. Improves toughness,
grainstructure, high temperature strength, wear resistance, etc.
Vanadium(V) Increases wear resistance, high temperature strength, retention of hardness etc.
Silicon(Si) It is a deoxidizing agent. Increases strength and wear resistance. It is of importance that certain
elements are as low as possible. Elements like Hydrogen, Oxygen, Nitrogen, Phosphorous, Sulphur create defects
inside & also reduce the mechanical properties of steels.

Hardening: Heat uniformly to 823/850C until heated through. Quench in oil.

Tempering: Heat uniformly and thoroughly at the selected tempering temperature, up to 660C and hold at heat for
two hours per inch oftotal thickness. Tempering between 250-375C in not recommended as this can seriously
reduce the steels impact value.

Stress Relieving:
Heat slowly to 650-670C, soak well before cooling the EN24 tool in a furnace or in air.

Mechanical Properties
                         Tensile   Yield                                      Proof
              Heat                          a% on Impact Impact                        Hardness        Size
                         Strength Stress                                      Stress
            Treatment                     5.665ÖSo Izod J KCV J                          HB            mm
                        Rm N/mm² Re N/mm²                                     rp0.2
                T       850/1000    654       13     40    35                  635     248/302    >150≤250
                T       850/1000    680       13     54    50                  665     248/302    >63≤250
                U       925/1075    755       12     47    54                  740     269/331    >29≤100
                V       1000/1150   850       12     47    42                  835     293/352     >13≤63
                W       1075/1225   940       11     40    35                  925     311/375     >6≤29
                X       1150/1300  1020       10     34    28                 1005     345/401     >6≤29
                Z         1550     1235        5     10     9                 1125       444       >6≤29



Vindhyavesh Tripathi
vatripathi@rediffmail.com
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Description: Metallurgical information abut Material En 24/817M40T/34CrNiMo6/35NCD6/AISI-SAE 4340/German Werkstoff No. 1.6582/EN10277-5