Normalizing, say again, often is the steel is heated to DIN 17155 HI Ac3 (Ac is refers to the heating of all free ferrite to austenite end temperature, generally from 727 ℃ to 912 ℃) or Acm (Acm) is the actual heating in hypereutectoid steel completely austenitizing critical temperature line) more than 30 ~ 50 ℃, the heat preservation after a period of time, take out the DIN 17155 HI steel from the furnace and in the air or water spray, spray or cooling metal heat treatment process.
Its purpose is to make DIN 17155 HI steel grain refinement and carbide distribution uniformity.
Difference is normalized normalizing and annealing cooling speed was faster than the annealing cooling rate, thus normalizing group is more fine than annealing organization, its mechanical properties are improved. On the other hand, are outside the furnace cooling do not take up device, high productivity, so as far as possible in production by normalizing instead of annealing. For complex shape important forgings, and high temperature tempering after normalizing (550-650 ℃), high temperature tempering to eliminate normalizing the stress formed during cooling, improve the toughness and plasticity.
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