cold drawn tubes

Precision tube temperature quenching ductility carbon steel after heat treatment for austenitic organization

Precision tube temperature quenching ductility carbon steel after heat treatment for austenitic organization, in 250 ~ 400 ℃ temperature range quenching steel embrittlement, the significant increase in the ductility transition temperature ductility. Cryogenic tempering embrittlement precision tube can't be used to heat removal, therefore is also called % 26 other Irreversible quenched cold drawn tubes ductile throughout % 26; . Key in alloy tool steel, alloy structural steel, high strength precision tube. A fracture is the intergranular fracture has embrittlement precision tube or the intergranular and class quality, and the mixed fracture.
The reason of cryogenic hardening ductility widely thought: and pearlite to flake shape in ultra-low temperature quenching process in the original martensite position precipitation is closely related to the fault, lead to dislocation embrittlement. Residue in the original element phosphorus markov fault position partial poly is one of the ultra-low temperature quenching ductility sake. Phosphorus content was less than 0.005% of high purity precision tube does not cause cryogenic hardening ductility. Phosphorus in the heat generated when markov fault position partial poly, save out after heat treatment. Phosphorus in the original markov fault position when partial poly and pearlite quenching in the original martensite precipitation position is wrong, the two factors lead to the intergranular brittle fracture, prompted the ultra-low temperature quenching ductility.
But in view of the precision of steel tube surface rust, scale, welding scar can not eliminate, must further rely on other methods. Special tool antirust processing precision steel tube surface scale, rust, welding scar, can choose steel beam impact tubes brush to clean up fine polishing the surface treatment. Special tool driving force divided into manual type, two kinds of antirust processing, hand tools antirust processing can do Sa2 level, antirust treatment can achieve Sa3 level driver specialized tools. Precision steel tube surface such as adhesive solid oxide skin especially, is likely to rely on special tool antirust treatment also can not solve the clean and tidy, need to find other ways.
Pickling passivation pickling passivation generally contain organic chemical and electrolytic process two kind of way. But pipeline corrosion protection using only organic chemical pickling passivation. Organic chemical pickling passivation can be precision steel tube surface do certain cleanliness, surface roughness, convenient anchor behind the lines. Usually as a shot (sand) to solve. Blast spray according to the power of the motor drive, high speed, the steel grit, steel shot, steel wire section, minerals, such as wear-resistant materials under the action of inertial force of precision steel tube surface spray mass ejection solution, on the one hand, fast cleaning rust, metal oxides side impact beams and waste, on the other hand precision steel tube in wear resistant material, with a strong impact and the effect of the sliding friction to do necessary to trim surface roughness. Blast spray pipe is antirust treatment idealized method, general blasting antirust treatment is suitable for precision steel pipe surface treatment, sandblasting derusting is suitable for precision steel tube outer surface processing.


Marshall

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