Question

what is difference between tempering and aging?

Answer 1

Tempering is a heat treatment technique applied to ferrous alloys, such as steel or cast iron, to achieve greater toughness by decreasing the hardness of the alloys where as when a precipitation hardening alloy is quenched, its alloying elements will be trapped in solution, resulting in a soft metal. Aging a "solutionized" metal will allow the alloying elements to diffuse through the microstructure and form intermetallic particles. These intermetallic particles will nucleate and fall out of solution and act as a reinforcing phase, thereby increasing the strength of the alloy. Alloys may age "naturally" meaning that the precipitates form at room temperature, or they may age "artificially" when precipitates only form at elevated temperatures. In some applications, naturally aging alloys may be stored in a freezer to prevent hardening until after further operations - assembly of rivets, for example, may be easier with a softer part.

Answer 2

dear fellow, In tempering of martensite, when you will increase temperature then carbon will precipitate out from martensite structure and due to precipitation hardening will increase hardenss.... in aging and tempering, both we have super saturated solid solution, we heat them, second phase precipitate out causing increase in hardness, then more temperature and time will increase grain size, which will lead to decrease in hardness.......

Answer 3

@prateek..... with tempering we can increase hardness as well