6F7 ESR Tool Steel - 1.2767 ESU - 45NiCrMo16 - JIS ~SKT 6

Where can 6F7 tool steel be used?

With its durability, longevity, high hardness and toughness and its resistance to thermal fatigue and cracking the 6F7 ESR is suitable for many applications and industries like the manufacturing, machining, automotive, plastics, toolmaking and medical industry.

Is the 6F7 ESR a stainless steel?

To be classed as stainless steel a steel grade has to have a minimum mass fraction of 10.5% of chromium. The 6F7 ESR has a mass fraction of 1.2 - 1.5% of chromium and will therefore stain in corrosive or wet environments.

Is tool steel 6F7 ESR corrosion resistant? 

To be corrosion resistant the 6F7 ESR should have a minimum of 10.5% of chromium. As it only has a content of 1.2 - 1.5% of chromium it is not classed as a corrosion resistant steel.

Is tool steel 6F7 ESR magnetizable?

Like most tool steels the 6F7 ESR is composed of iron and carbon, the iron makes the steel grade magnetizable and are so called ferromagnetic steels. 

Grinding, milling and eroding for example can be done on machines using magnetic clamping.

Heat treatment for tool steel 6F7 ESR

Annealing tool steel 6F7 ESR

Heat the material to a uniform temperature of 1130 - 1202°F (610 - 650°C) and hold for 2 - 5 hours and slowly cool at a rate of 50 - 68°F (10 - 20°C) to about 1112°F (600°C) in the furnace and then continue the cooling phase in air.

45NiCrMo16 Stress relieving tool steel 6F7 ESR

After rough machining, grinding or shaping, heat the parts uniformly to a temperature of 1202°F (650°C) and hold for 2 hours in a neutral atmosphere. To finish the process let the parts cool slowly in the furnace. Uniform and controlled heating and cooling the 6F7 ESR can avoid creating new thermal stresses and possible dimensional changes.

Hardening tool steel 6F7 ESR

Preheat the material to 1202°F (650°C) uniformly, then take the temperature to 1544 - 1598°F (840 - 870°C) and hold for 15 - 30 minutes when the temperature has equalized.

Quenching 6F7 ESR tool steel

Following are a few quenching methods, they should be chosen carefully and with properties and applications, they are selected for, in mind.

• Air
• Warm oil (approx.176°F / 80°C)
• Salt bath (572 - 752°F / 300 - 400°C)
• Gas

45NiCrMo16 Tempering tool steel 6F7 ESR

Immediately after hardening the 6F7 ESR, heat the parts slowly to the chosen tempering temperature. It is recommended to temper the parts twice. Let parts cool to room temperature between tempers. The chosen temperature should be held for a minimum of 2 hours or 1 hour per inch (25.4 mm) of thickness.

To avoid undesirable deformation during plastic molding, the tempering temperature after hardening should be 122°F (50°C) higher than the operating temperature.

Dimensional changes of tool steel 45NiCrMo16

This steel grade, like most metals, can contract and expand when heated or cooled. Also during phase changes, from residual stresses and with decarburization there can be some dimensional changes which can affect the properties for this steel grade.

Controlled heating and cooling, stress relieving and avoiding overheating can reduce the risks of thermal shock and unwanted dimensional changes like warping or distortion but also cracking which potentially means to start a project anew. 

Electrical Discharge Machining (EDM) the 6F7 ESR

EDM is used for parts made from one individual piece, for cutting dies or when making intricate shapes and sharp corners. The former can be achieved when choosing the correct EDM process, electrode and parameters. The recast layer can be removed through stoning or polishing.

45NiCrMo16 Surface treatment for tool steel 6F7 ESR

There are a variety of surface treatments available for tool steel 6F7 ESR to enhance wear resistance, hardness and corrosion resistance. The surface treatment should be carefully chosen with consideration to where and what the material will be used for. Following are a few examples of surface treatments for the 6F7 ESR.

Nitriding tool steel 6F7 ESR

Nitriding diffuses nitrogen into the surface of the steel and gives it a harder and more wear resistant surface. It can improve the fatigue life and corrosion resistance of the 6F7 ESR.

Carburizing tool steel 6F7 ESR

Carburizing diffuses carbon into the surface of the material which gives the surface a higher hardness and wear resistance.

Carbonitriding tool steel 6F7 ESR

This process diffuses nitrogen and carbon into the surface of the metal giving it a higher hardness and wear resistance.

Boronizing (Boriding) tool steel 6F7 ESR

Boronizing layers the material surface with a very hard boride layer. This praxis is used for tools or components with high abrasive wear. 

Hard chrome plating tool steel 6F7 ESR

This process adds a layer of chromium on the surface of the steel. Chrome plating improves wear and corrosion resistance.

Physical Vapor Deposition / Chemical Vapor Deposition for tool steel 6F7 ESR

Both processes overlay the material with a thin, hard coating. The process can enhance hardness, improve wear  resistance and reduce friction.

Polishing tool steel 6F7 ESR

It is possible to polish this material grade to a high gloss finish.

Machinability of tool steel 6F7 ESR

Forging tool steel 6F7 ESR

Slowly and uniformly heat the material to a temperature range of 1562 - 1922°F (850 - 1050°C). Soak and then cool slowly in the furnace to 1112°F (600°C) and then cool  the 6F7 ESR further down in air.

Welding tool steel 6F7 ESR

Due to cracking and mechanical property changes in the weld area, welding should be avoided. If welding is unavoidable the material should be welded in the annealed condition and pre- and post heat treatment is advised.

Grinding 6F7 tool steel

Select the correct grade of grinding wheel and make sure it is in good condition with suitable dressing tools. 

Wear resistance for tool steel 6F7 ESR

The wear resistance for tool steel 6F7 ESR scores a 2 on a scale where 1 is low and 6 is high.

Tensile strength of tool steel 6F7 ESR

Tool steel 6F7 ESR has a tensile strength of approx. 127.6 KSI on delivery (0.145 KSI = 1MPa). In order to reach this value, a tensile test is performed to show how much force is needed to stretch or elongate a sample before it breaks.

Working hardness for tool steel 6F7 ESR

The working hardness for tool steel 6F7 ESR is 469 - 534 BHN (50 - 54 HRC).

Specific heat capacity for tool steel 6F7 ESR

The specific heat capacity of tool steel at room temperature is 460 J/g-°C (0.109 BTU/lb-°F). This value shows how much heat is needed  to heat 1lb of material by 1 Fahrenheit.

Continuous TTT-diagram for tool steel 6F7 ESR

This diagram shows the micro changes at different temperatures which are important during heat treatment. They show the optimum condition for the hardening, annealing and normalizing process.

Isothermal TTT-diagram for 6F7 ESR tool steel

The following diagram shows the structural changes at micro levels over time at a constant temperature. It shows at what temperatures the different phases, e.g., perlite, martensite and bainite start to form.

Steel Properties for tool steel 6F7 ESR

Cold work for tool steel 6F7 ESR

Cold work steels are used for working temperatures up to 392°F (200°C) and are suited for applications like molds, cutting tools and cold hobbing for example. 

Density for tool steel 6F7 ESR

Typically the density of 6F7 ESR tool steel is 0.284 lb/in3 (7.85g/cm3) at room temperature.

Thermal conductivity of tool steel 6F7 ESR

The following table shows the thermal conductivity of tool steel 6F7 ESR at various temperatures.

Thermal expansion coefficient for tool steel 6F7 ESR

The following table shows expansion or contraction at various temperatures, which may be very important for high temperature works or when working with high temperature changes.

Specific electrical resistivity of tool steel 6F7 ESR

The following table shows the electrical resistivity of tool steel 6F7 ESR.

Modulus of elasticity (Young’s Modulus) for tool steel 6F7 ESR

The stress and strain modulus or modulus of elasticity (Young’s modulus) for tool steel 6F7 ESR is at 30.46 KSI (210 GPa). 

Is tool steel 6F7 ESR a knife steel?

Tool steel 6F7 ESR can be used to make knives as it has high hardness, wear resistance and toughness which are needed in knife making. Due to its high hardness it is harder to sharpen, its low corrosion resistance means it should be regularly maintained to prevent corrosion. 

ESR material has fewer inclusions and its carbides are distributed more uniformly this might give the knife a better finish and can have a sharper edge.

Conclusion

As an ESR steel with a special purity and homogeneousness the 6F7 ESR has a unique combination of wear resistance, toughness and hardness. Those properties make the 6F7 ESR a great choice for applications which are demanding and use high stress components. Careful consideration of use, properties needed, appropriate heat treatment and maintenance is required to reduce unwanted changes or risks.  

Datasheet for tool steel 6F7 ESR

As a steel supplier we provide you with the datasheet for tool steel 6F7 ESR in PDF format.

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