AISI SAE H-13 Tool Steel

AISI SAE H-13 is an air hardening tool steel which combines a very good red-hardness with toughness and covers a wide variety of application. H13 hot work tool steel may be water cooled in service and gives high temperature strength and wear resistance. 

Forging: Heat slowly and uniformly to 700°C. Forge within a range of 1050/1150°C reheating if necessary, since forging must not be carried out below 850°C. Cool slowly, preferably in a furnace since this is an air hardening steel.

Annealing:Heat uniformly to 750/800°C, soak thoroughly and furnace cool.

Stress Relieving:
After rough machining the tools must be stress relieved, heat to 650/700°C and hold for 2 hours then furnace cool.

Hardening:
Pre heat to 750/850°C and soak thoroughly, then increase rapidly to the hardening temperature of 1000/1030°C in a controlled atmosphere or neutral salt bath. Cool in air.

This steel is suitable for vacuum hardening.

Tempering:
Heat uniformly and thoroughly at the selected tempering temperature, depending on the hardness requirement. Hold for at least two hours per inch of total thickness and cool in air. Double tempering is st rongly recommended.

Chemical Composition
C.	Si.	Mn.	Cr.	Mo.	V.
0.38%	1.00%	0.40	5.00%	1.30%	1.00%

Tempering °C	400	500	550	600	650
HRc	54	56	54	49	47

Tufftriding:
Tufftriding H13 tool steel is done in a special salt bath at 570°C. Holding time 2 hours. I gives a surface hardness of approximately 950-1000HV.

Nitriding:
Nitriding H13 hot work tool steel gives a hard surface case which is very resistant to wear and erosion and also increases the corrosion resistance. Nitriding in ammoniac gas at 525°C gives a surface hardness of approximately 1000HV 1250HV. Before nitriding, the tool should be hardened and tempered at approximately 50°C above nitriding temperature.

Welding:
Due to the high risk of crack formation welding of H13 tool steel should be avoided, if possible. When, howe ver welding is essential, the following serves as a guide:

A .   Welding of soft annealed H13 tool steel
·       Preheat to 300 - 500°C
·       Weld at  300-500°C
·       Immediately stress relieve at 675-750°C. Soaking time at temperature, 3 hours.
Electrode: Cr-Mo alloy electrode for welding low alloyed steel.

B.    Welding in connection with hardening of soft annealed H13 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.
Electrode: Hard facing electrode.

C.    Repair welding of H13 tool steel in hardened and tempered condition.
·       Preheat to the tempering temperature (min. 300°C) previously used.
·       Weld at tempering temperature. Do not weld below 150°C.
·       Reheat immediately to 300°C. Soaking time 3 hours.
·       Cool in air to approx. 80°C.
·       Reheat immediately to 300°C. Soaking time 3 hours.
Electrode: Hard facing electrode.

Physical Properties:	Temperature:
	200°C	400°C	600°C
Density (Kg/dm³)	7.75	7.70	7.65
Coefficient of thermal expansion (per °C from 0°C)	11.9 x 10-6	12.4 x 10-6	12.8 x 10-6
Thermal conductivity (cal/cm.s °C)	60.0 x 10-3	62.4 x 10-3	63.6 x 10-3
Modulus of elasticity:
N/mm²	184 000	175 000	154 000