817M40 is a 1.5% Ni-Cr-Mo high hardenability, high tensile strength steel.

817M40 is generally supplied in the Hardened and Tempered condition in the tensile range of 850 – 1000Mpa (T Condition) but can be heat treated to 850 – 1550Mpa dependent on section size (T – Z Condition). It could also be supplied in the annealed condition suitable for pre-heat treatment machining.

This grade is very popular and widely used for many high strength applications where a good combination of strength and impact properties are essential in fairly large components.

This alloy is used in most industry sectors for a wide variety of applications including high strength machine parts, collets, spindles, gears, bolts shafts and couplings.

RELATED SPECIFICATIONS 817M40 – 1.5% Ni-Cr-Mo Steel
BS970 – 1955 EN24
DIN 34CrNiMo6
W.Nr. 1.6582
AISI 4340
TYPICAL CHEMICAL COMPOSITION
Carbon 0.40%
Silicon 0.25%
Manganese 0.60%
Phosphorous <0.040%
Sulphur <0.040%
Chromium 1.20%
Molybdenum 0.28%
Nickel 1.55%
Mechanical Property Requirements – BS970 Part 3 1991
Condition Rulling Section Tensile Strength Mpa Yield (0.2%) Mpa Elongation % Izod Ftlbs Charpy J Hardness HB
T 250 850/1000 635 13 30 35 248-302
U 150 925/1075 740 12 35 42 369-331
V 63 1000/1150 835 12 35 42 293-352
W 29 1075/1225 925 11 30 35 311-375
X 29 1150/1300 1005 10 25 28 341-401
Y 29 1225/1375 1080 10 18 21 363-429
Z 29 1550 Min
 1125 5 8 9 444 Min
FORGING
Forging Temperature for this material should be 850 – 1200oC

Soak times should be kept to a minimum to avoid heavy scaling, but sufficient time should be given to allow centre to achieve furnace temperature.

After forging pieces should be allowed to cool in still air.
HEAT TREATMENT
Annealing – Heat to 800 – 850oC for a time commensurate with ruling section and furnace cool.
Hardening – Heat to 830 – 860oC for a time commensurate with ruling section and quench in Oil, Water or Polymer.

Note: If water quench is to be used, although not recommended, care must be taken to ensure that all sharp corners are removed prior to heat treatment.
Tempering – Re-heat to 450 – 660oC as required, dependent on final required properties. Hold for a time commensurate with the ruling section and cool in still in air.
MACHINING
817M40 has good machinability in the quenched and tempered condition, dependent on condition, and operations such as sawing, turning, broaching, milling etc can be accomplished satisfactorily using standard machine tool manufacturers recommended speeds and feeds.
WELDING
Welding of 817M40 in the hardened and tempered condition is not advised and should be avoided if possible, as the mechanical properties will be altered in the heat affected zone. If welding is required it should be done using low hydrogen electrodes, while the material is in the annealed condition, and the work piece should be stress relieved (640 – 660oC) immediately after cooling to hand warm, prior to hardening and tempering.

If welding in the quenched and tempered condition, the work piece should be stress relieved at 15oC below the original tempering temperature.

Pre-heat temperature should be at least 370oC