Temper-brittleness also can be known as temper embrittlement, where temper embrittlement is also belongs to the method of tempering. Temper Embrittlement is a method reduces the impact toughness of steels. In many alloy steels, temper embrittlement also can classify in 2 methods which is irreversible temper brittleness and reversible temper brittleness. Where usually irreversible temper brittleness happens in the range of temperature 250-400°C and reversible temper brittleness happens in the range of 450-650°C. Temper-brittleness this method has the greatest effect on Martensite structures. As comparison of Martensite, Banite and Pearlite, Martensite will be on rank 1 follow by Banite then to Pearlite. It appears to be associated with the segregation of solute atoms to the grain boundaries by lowering the boundary strength.