A Brief Comparison between Flame Hardening and Induction Hardening

25 May 2022

Metals already boast tons of properties that make them beneficial for manufacturers. Some of their properties include excellent ductility, good conductivity of heat and electricity, and high tensile strength. They are likewise hard, lustrous, and resistant to elements.

But to further improve the strength, malleability, ductility, and abrasion resistance of metals, they can undergo a wide array of heat treatment processes. Heat treatment is conducted by heating the metal workpieces before reaching their molten phase. They are then cooled in a controlled way, making sure that they acquire the needed mechanical properties.

Two heat treatment processes that metal workpieces can undergo are flame hardening and induction hardening. Understanding their differences can help business owners like you know the best heat treatment process for your metal workpieces.

Flame Hardening

Flame hardening is a surface hardening method wherein metal workpieces are exposed to a high-temperature flame before quenching them. Some metal workpieces that can undergo this surface hardening method are alloy steels, mild steels, cast iron, and medium carbon steels.

When carrying out flame hardening, the operator must utilise direct heat from oxy-gas flames to heat the metals until they reach their austenitizing temperature. Once this temperature has been reached, the surface of the materials will change while their core remains unchanged. The process of quenching must then be carried out upon reaching their austenitizing temperature, providing them with a harder surface that is more resistant to corrosion and wear. 

Remember, however, that the result of flame hardening will be determined by the flame temperature, heating duration and speed, quenching temperature, and elemental composition of the metal workpieces.

Induction Hardening

Induction hardening, on the other hand, is a surface hardening method that places metal workpieces inside a copper coil to heat them within or above their transformation temperature. The coil is utilised to generate an alternating current, inducing an alternating magnetic field to the workpieces to effectively heat their surfaces. After heating their surfaces, they are quenched to attain the needed alterations.

Some metal workpieces that can undergo induction hardening are carbon steels, alloy steels, stainless steels, cast iron, and ductile iron. Somehow similar to flame hardening, induction hardening can also enhance the surface of workpieces by increasing their wear resistance, surface hardness, and fatigue life. It does not likewise affect their core microstructure.

The output of induction hardening may depend on power level, dwell time, and other process variables. It can also be affected by the elemental composition of the metal workpieces.

Primary Differences

One key difference between flame hardening and induction hardening is that the latter does not operate in an open flame. Induction hardening only heats materials through a coil, making it more precise. It does not likewise generate scaling, decarburisation, and overheating damage. Flame hardening, however, can still be utilised in processing irregular workpieces. It also has lower equipment and maintenance costs than induction hardening.

To know more about these heat treatment processes, you can call us at Alpha Detroit Heat Treatment.

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