Factors Affecting the Quality of Quenched and Tempered 45Cr Steel

The level of operators is an important factor affecting the quenching and tempering quality of 45Cr steel. At the same time, there are many reasons such as equipment, materials and processing before quenching and tempering.

(1) The speed of transferring 45Cr steel from the heating furnace to the cooling tank is slow, and the temperature of the entering water decreases to cause partial decomposition. The 45Cr steel has an incompletely quenched structure and cannot meet the hardness requirements. Therefore, the cooling liquid of small parts should pay attention to the speed, and the large 45Cr steel should be cooled by master the time.

(2) The amount of 45Cr steel furnace should be reasonable, preferably 1~2 layers, 45Cr steel overlaps each other to cause uneven heating, resulting in uneven hardness.

(3) The arrangement of 45Cr steel into the water should keep a certain distance, too dense will hinder the rupture of the steam film near the 45Cr steel, resulting in low hardness of the 45Cr steel near the surface.

(4) Quenching in the furnace should not be completed in one go. Depending on the degree of furnace temperature drop, the furnace should be closed and the temperature raised again so that the hardness of the 45Cr steel is consistent before and after.

(5) Pay attention to the temperature of the coolant. If the temperature of 10% brine is higher than 60℃, it cannot be used. The coolant should not have oil, mud and other impurities, otherwise, the hardness of 45Cr steel will be insufficient or uneven.

(6) Unprocessed blanks are quenched and tempered, and the hardness will not be uniform. If good quenching and tempering quality is to be obtained, the blanks should be rough-turned, and the bars should be forged.

(7) Strictly control the quality. After quenching, the hardness of 45Cr steel is 1~3 units lower. The tempering temperature can be adjusted to meet the hardness requirements. But it must not be tempered only at medium or low temperature to meet the requirements of the drawings. Otherwise, Lost the meaning of tempering, and may have serious consequences.