Tempering furnace tempering brittleness temperature range

An introduction to the temperature range of tempering brittleness in a furnace

(1) The brittleness of low-temperature tempering quenched steel in the tempering furnace range of 250℃ ~ 3500℃ is called low-temperature tempering brittleness, also known as quasi-tempering brittleness. This brittleness is present in almost all steel. This is an irreversible temper brittleness, and there is no effective way to completely eliminate this kind of temper brittleness. Therefore, tempering is generally not within the temperature range of 250℃ ~ 350℃.

(2) High temperature tempering brittleness of quenched steel in the range of 500℃ ~ 650℃ is called high temperature tempering brittleness, also known as the second type of tempering brittleness. This brittleness mainly occurs in structural steels containing Cr, Ni, Si, Mn and other alloying elements. This brittleness is related to heating and cooling conditions. Brittleness occurs when the annealing furnace is heated to above 600℃ and passes through the embrittlement temperature zone at a slow cooling rate. When passing through the embrittlement zone quickly, there is no brittleness. This type of tempering brittleness is reversible. After the emergence of type II tempering brittleness, the brittleness can be eliminated by reheating to above 600℃ and fast cooling.