What are the practical applications of heat treatment of metals?

Question

I know it's used to harden metals,but what are the practical applications of such metals parts?

please,as much explanations and examples as you can.

Thanks

Answer 1

All metals used in manufacturing are heat treated to varying degrees.  However some metals receive extra heat treatment.  Heating metal improves the hardness for use in certain type of bolts.  Soft metals like brass and copper are often heat treated.  Older types of military armor on tanks and such used heat treated metal.  Most modern armor uses different technology.  Heating also strengthens the valence bond (thus making it hard) which gives the added benefit of making the metal less reactive.  Therefore heat treated metals can be used for counter tops, lab equipment, and the like where stainless steel wouldn't be appropriate.  In the home we find heat treated (tempered) metal on such things as mower blades, axes, and knives.  Saw blades, drill bits, garden tools also are heat treated.  The harder metal can be sharpened and will retain sharpness longer than untempered metal.  Swords of course are heat treated.  One odd application is locks, the harder metal resists impact and doesn't change shape due to temperature.  However there are disadvantages to heat treated metal, harder does not mean stronger in all cases.  High heat treated metals are more brittle, they are not useful for items subject to sheering or stretching forces.  Heat treated components can fail suddenly, almost like a dry twig being snapped (inelastic failure or non-ductile failure are the engineering terms for this).  Obviously bridges, high pressure systems, and most constructions applications will not use heat treated components.

One other use of heat treatment is in artistic applications.  Because heat changes the color of metals artists can use various methods including propane torches or various fires (coal, wood) to make a lasting color without using paint.  You can find many examples of metal artistry on the web.

Answer 2

Hope you got sufficient explanation.

Some applications are, crank shafts, levers, connecting rods, vices, steel pipes(non hollow), cutting tools, machine beds such as lathe, universal testing machine, etc.

It can be defined as the process in which the material is taken to its critical temp state and cooled to normal state.

Process names are, quenching, oven cooling, air cooling, nitriding, carburising, cyaniding.

There are many types of heat treatment such as surface heat treatment, whole body treatment, part treatment, age hardening etc. Mainly surface treatment is used.

It can be done to increase the hardness or to decrease the hardness.

Technical terms used martensite, austensite, ttt diagrams etc