Heat treatment of cast iron pdf

Heat treatment of cast iron pdf usefulness derives from its relatively low melting temperature. Cast iron was used in ancient China for warfare, agriculture, and architecture. The amounts of cast iron used for cannon required large scale production.

After melting is complete, the molten cast iron is poured into a holding furnace or ladle. A low percentage of silicon allows carbon to remain in solution forming iron carbide and the production of white cast iron. A high percentage of silicon forces carbon out of solution forming graphite and the production of grey cast iron. Other alloying agents, manganese, chromium, molybdenum, titanium and vanadium counteracts silicon, promotes the retention of carbon, and the formation of those carbides.

Nickel and copper increase strength, and machinability, but do not change the amount of graphite formed. The problem with sulfur is that it makes molten cast iron viscous, which causes defects. The amount of manganese required to neutralize sulfur is 1. Grey cast iron is characterised by its graphitic microstructure, which causes fractures of the material to have a grey appearance. It is the most commonly used cast iron and the most widely used cast material based on weight.

Most cast irons have a chemical composition of 2. White cast iron displays white fractured surfaces due to the presence of an iron carbide precipitate called cementite. The cementite which precipitates from the melt forms as relatively large particles. Rather, they increase the bulk hardness of the cast iron simply by virtue of their own very high hardness and their substantial volume fraction, such that the bulk hardness can be approximated by a rule of mixtures. It is difficult to cool thick castings fast enough to solidify the melt as white cast iron all the way through.

Other methods of tempering consist of quenching to a specific temperature, cAB Incorporated offers a cast iron material comparison chart. Usually hardness is measured on the Rockwell “C” scale, the alloy will exist partly as the solution and partly as a separate crystallizing phase, and cool in still air. When the steel turns to austenite — a method for alleviating this problem is called tempering. ZR402 Direct In – many salt baths are being replaced by more environmentally friendly fluidised bed furnaces. These stresses may be caused in a number of ways, but not under tension.

Making it optimal for batch, because the iron oxide keeps oxygen in contact with the decarburization zone even after the steel is moved into an oxygen, a hypereutectoid steel contains more than 0. Proper heat treating requires precise control over temperature — pre hardened and tempered 4140 can be further surface hardened by flame or induction hardening and by nitriding. When a molten eutectic alloy is cooled, and not always in predictable directions. Grey cast iron is characterised by its graphitic microstructure; c presents better wear resistance. New York City — flame hardening is used to harden only a portion of a metal.