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 Precision tube manufacturer
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Precision tube manufacturer

Contact person: manager Yan
Hand machine: 13603273751
Tel: 13603273751
Address: No.1, North Hehai village, JIANGGUANTUN office, Liaocheng Economic Development Zone, Shandong Province (ANZ logistics company)

Temper brittleness of finish rolled tube at low temperature

Release time: September 12, 2020 popularity: fifteen

according to Precision tube The tempering temperature range of brittleness can be divided into low temperature temper brittleness and high temperature temper brittleness.

   Finishing tube The martensite structure of low temperature tempered brittle alloy steel is obtained by quenching. Tempering in the temperature range of 250 ~ 400 ℃ makes the steel embrittlement, and its toughness brittleness transition temperature increases obviously. The brittle precision tube can not be eliminated by low temperature tempering heating, so it is also called% 26quo; Irreversible temper brittleness% 26rdquo;. It mainly occurs in alloy structural steel and low alloy ultra-high strength precision pipe. The fracture of brittle precision tube is intergranular fracture or mixed fracture of intergranular and quasi cleavage. It is generally believed that: (1) cementite precipitates in the original austenite grain boundary in the form of flake during low temperature tempering, which results in grain boundary embrittlement( 2) The segregation of impurity elements such as phosphorus at the grain boundary of the original austenite is also one of the reasons for low temperature temper embrittlement. Low temperature temper embrittlement does not occur in high-purity precision tubes containing less than 0.005% phosphorus. Phosphorus segregation occurs at austenite grain boundary when heated by fire and retained after quenching. The segregation of phosphorus at the grain boundary of the original austenite and the precipitation of phosphorus in the original austenite grain boundary during the tempering of cementite cause intergranular brittle fracture, which contribute to the occurrence of low temperature temper embrittlement.

The alloy elements in precision tube have great influence on the low temperature temper brittleness. Chromium and manganese promote the segregation of impurity elements such as phosphorus at the austenite grain boundary, thus promoting the low temperature tempering brittleness. Tungsten and vanadium have no effect on it. Molybdenum reduces the ductile brittle transition temperature of low-temperature tempered precision tube, but it is not enough to restrain the low-temperature temper brittleness. Silicon can delay the precipitation of cementite during tempering and increase its formation temperature, so it can increase the temperature of brittleness of precision tube during low temperature tempering.


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