Hot Die Steel H13

Preheat slowly to 750°C then increase the temperature more rapidly to 900-1100 °C. Do not forge below 850°C. It is essential to cool the H13 slowly after forging, either in a furnace or in vermiculite.

Soak thoroughly at 740 – 780°C before furnace cooling at a maximum rate of 20°C per hour down to 600°C followed by cooling in air.

When tools made from H13 tool steel are heavily machined or ground, the relief of internal strains is advisable before hardening to minimise the possibility of distortion. Stress relieving should be done after rough machining. To stress relieve, heat the component carefully to 700°C, allow a good soaking period (two hours per 25mm of ruling section). Cool in the furnace or in air. The tools may then be finish machined before hardening.

Preheat to 780-820°C. Soak thoroughly, then increase rapidly to the final hardening temperature of 1070-1150°C. When the H13 has attained this temperature, soak for approximately thirty minutes. Cool in air. Large sections may be quenched in oil.

Heat uniformly to the required temperature allowing a soaking time of two hours per 25mm of ruling section. Withdraw from the furnace and allow to cool in air. A second tempering is strongly recommended, the H13 tool being allowed to cool to room temperature between tempers. The usual tempering range is 530-680°C depending on the hardness requirements and the operating temperature of the tool.

In general, we do not advise the welding of tool steel but users sometimes prefer to weld in order to avoid the cost of retooling. It should be remembered that this grade is an air hardening steel and that in welding the area of the weld attains a temperature of about 1000°C. Cracking is likely to occur during cooling unless proper precautions are taken. Popular methods of welding are atomic hydrogen and argon arc. We recommend you contact your welding consumables supplier who should provide you full assistance and information on welding tool steels.

1) It is desirable to anneal the tool prior to welding but with care welding may be done on hardened and tempered tools.
2) It is important to preheat the die to 300-500°C and to maintain this temperature during welding.
3) After the weld has been completed, maintain at 300-500°C for one hour, then cool the die slowly in a furnace or in insulating material.
4) If the tool has been annealed prior to welding, stress relieve at 700°C before re-hardening.
5) If the tool has not been annealed prior to welding, re-temper at 550-600°C for a minimum of 2 hours.

H13 tool steel can be nitrided to give a hard surface case. The steel is then very resistant to wear and erosion. Nitriding also increases resistance to corrosion. Nitriding in ammoniac gas at a temperature of 525°C will give a surface hardness approximately 1000 to 1250HV. Before nitriding the tool should be hardened and tempered at approximately 50°C above the nitriding temperature. It is important to note that with increase in penetration of the nitriding, there is a reduction in resistance to thermal shock and an increase in embrittlement.

Heat treatment temperatures, including rate of heating, cooling and soaking times will vary due to factors such as the shape and size of each H13 tool steel component. Other considerations during the heat treatment process include the type of furnace, quenching medium and work piece transfer facilities. Please consult your heat treatment provider for full guidance on heat treatment of tool steels.