D2

Technical Data

BS4659 BD2 is a high carbon, high chromium, molybdenum, vanadium, air hardening alloy tool steel which offers good wear resistance, high surface hardness, through hardening properties, dimensional stability and high resistance to tempering effect. D2 tool steel is also suitable for vacuum hardening.

Forging:
Heat slowly and uniformly to 700°C then more rapidly to 900/1040°C.  After forging cool slowly.

Annealing:
Anneal at 850°C and slow furnace cool. Hardness after annealing will be approx. 225 brinell.

Hardening: 
Pre heat slowly to 750/780°C and thoroughly soak. Continue heating to the final hardening temperature of 1000/1030°C and allow the component to be heated through. Quench in oil or cool in air.

Tempering:
Heat uniformly and thoroughly at the selected tempering temperature and hold for at least one hour per inch of total thickness. Double tempering should be carried out with intermediate cooling to room temperature.

Tempering °C	150	200	250	300	350	400
HRc	62/61	61/60	60/59	57/56	56/55	56/55

Stress Relieving:
If machining operations have been heavy or if the tool has an unbalanced section, remove stresses before hardening by heating up to 700°C, equalise, then cool slowly.

Hard Chromium Plating:
After hard chromium plating tempering of D2 tool steel is recommended at 180°C for 4 hours to avoid hydrogen embrittlement.  Tempering is to be performed immediately after chromium plating.

Welding:
Due to the high risk of crack formation welding of D2 tool steel should be avoided, if possible. When, howe ver welding is essential, the following serves as a guide:

A.   Welding of soft annealed D2 tool steel. 
·       Preheat to 300 - 500°C
·       Weld at 300-500°C
·       Immediately stress relieve
Electrode: Cr-Mo alloy electrode for welding structural steel.

B.    Welding in connection with hardening of soft annealed D2 tool steel.
·       Heat to austenitizing temperature.
·       Cool to approx. 500°C
·       Weld at approx. 500°C
·       Cool to approx. 100°C in the same way as at normal hardening, then temper to desired hardness. Double tempering will
     reduce the risk of crack formation.
Electrode: Hard facing electrode.

C.    Repair welding of D2 tool steel in hardened and tempered condition.
·       Preheat to the tempering temperature (min. 200°C) previously used.
·       Weld at tempering temperature
·     Heat immediately to tempering temperature, but max. 300°C. Soaking time 2 hours.
Electrode: Hard facing electrode.

BS4659 BD2 available in:-