Precision pipe is a kind of seamless steel pipe with high precision and high brightness produced by cold drawing or cold rolling process. Its internal and external diameter can be accurate to within 0.2mm. It not only ensures the bending and torsional strength, but also has light weight. Therefore, it is widely used in the manufacture of precision mechanical parts and engineering structures. It is also commonly used in the production of various conventional weapons, barrel, shell, bearing, etc.
After the low temperature tempering brittle alloy steel for precision tube is quenched to obtain martensite structure, tempering in the temperature range of 250 ~ 400 ℃ makes the steel brittle, and its toughness brittleness transformation temperature increases obviously. The embrittled precision tube can not be eliminated by low-temperature tempering and heating, so it is also called% 26ldquo; Irreversible tempering brittleness%26rdquo;. It mainly occurs in alloy structural steel and low alloy ultra-high strength precision pipe. The fracture of embrittled precision tube is intergranular fracture or mixed fracture of intergranular and quasi cleavage.