Precision tube is a high-precision, high-brightness seamless steel tube produced by cold drawing or cold rolling. Its inner and outer diameters can be accurate to within 0.2mm. While ensuring bending and torsional strength, it is light in weight, so it is widely used in the manufacture of precision mechanical parts and engineering structures.
After the precision bright tube is quenched to obtain martensite structure, it is tempered in the temperature range of 450-600℃; or after tempering at 650℃, it passes through 350-600℃ at a slow cooling rate; or after tempering at 650℃, it is heated for a long time in the temperature range of 350-650℃, which will cause the precision bright tube to become brittle. If the brittle 20# precision steel tube is reheated to 650℃ and then quickly cooled, the toughness can be restored, and the tempering brittleness can be reversed. High-temperature tempering brittleness is manifested as an increase in the toughness-brittleness transition temperature of the precision bright tube. High-temperature tempering brittleness. Sensitivity is generally expressed by the difference between the toughness-brittleness transition temperature of the toughened state and the brittle state. The more severe the high temperature temper brittleness is, the higher the proportion of intergranular fracture on the fracture of the precision bright tube is.
