Generally, the production process of seamless steel pipes can be divided into two types: cold and hot rolling. Hot -rolled, as the name suggests, the temperature of the rolling parts is high, so the deformation resistance is small, which can achieve a large deformation. Take the rolling of the steel plate as an example. Generally, the thickness of the casting blank is about 230mm, and after rolling and refined rolling, the final thickness is 1 ~ 20mm. At the same time, because the width ratio of the steel plate is small, the size and accuracy requirements are relatively low, it is not easy to occur on the plate -shaped problem, mainly to control the convexity.
The production process of cold -rolled seamless steel pipes is generally more complicated than hot rolling. The pipeline must be performed by three rollers. After squeezing, a fixed diameter test should be performed. Cut the grim about one meter.
The hot -rolled process sequence is as follows:
Round tube blank → heating → perforation → three -rolled oblique rolling, continuous rolling or squeezing → dehuminar → fixed diameter (or decrease) → cooling → straight → hydraulic test (or detecting) → marking → seamless steel pipes into warehouse It is made of a ingot or solid tube blank through perforation, and then made by hot rolling, cold rolling or cold. The specifications of seamless steel pipes are represented by outer diameter*wall thickness millimeters.
Seamless steel pipes are divided into two types: hot rolled and cold -rolled (dial) seamless steel pipes. Hot -rolled seamless steel pipes are divided into general steel pipes, low and low -pressure boiler steel pipes, high -pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes. Cold rolled (dial) seamless steel pipes, in addition to general steel pipes, low -medium -voltage boiler steel pipes, high -pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, other steel pipes, also include carbon thin -wall steel pipes, alloy thin -wall steel pipes, and alloy thin -wall steel pipes,, thin alloyed steel pipes, alloyed steel pipes, and alloyed steel pipes, alloyed steel pipes, and thin -walled steel pipes, and thin -walled steel pipes, alloyed steel pipes, Stainless thin -walled steel pipes, alien steel pipes.
The outer diameter of the hot rolled seamless pipe is generally greater than 32mm, the wall thickness is 2.5-200mm, the outer diameter of the cold-rolled seamless steel pipe can be 6mm, the wall thickness can be 0.25mm, and the outer diameter of the thin wall can be less than 0.25mm. Rolling is higher than hot -rolled size.
Generally, seamless steel pipes are made of high -alloy structure steel or 40Cr, 30CRMNSI, 45mn2, 40MNB and other high -quality carbon knot steel 16mn and 5MNV such as 10, 20, 30, 35, 45. 10, 20 seamless pipes manufactured by low -carbon steel are mainly used for fluid transportation pipelines.
The seamless pipes made of carbon steel in 45, 40Cr and other carbon steels are used to make mechanical parts such as cars and tractors. Generally, seamless steel pipes should be used to ensure strength and compression test. The hot -rolled steel pipe is delivered in a hot -rolled state or a hot treatment state; cold rolling is delivered to the hot treatment state.
