SAE1020, St37.4, St52 High Precision Cold Rolled Steel Tube Cold Drawn Seamless Steel Pipe

Precision steel pipe is a kind of high-precision steel pipe material after cold drawing or hot rolling. Due to the advantages of no oxide layer on the inner and outer walls of precision steel pipe, no leakage under high pressure, high precision, high finish, no deformation in cold bending, flaring, flattening and no cracks, it is mainly used to produce products of pneumatic or hydraulic components, such as air cylinder or oil cylinder, which can be seamless pipe or welded pipe.

Commonly used material
Commonly used materials are 10#, 20#, 35#, 45#, 20Cr, 40Cr, 20CrMo, 16Mn, 27SIMN, 304, 201, 310S, high quality carbon structural steel.

Precision tube characteristics

The characteristics of

1. Smaller outside diameter.

2. High precision can do small batch production.

3. Cold-drawn products have high precision and good surface quality.

4. The cross area of steel pipe is more complex.

5. The performance of steel pipe is superior, and the metal is dense.

According to the tempering temperature range of precision pipe brittleness, it can be divided into low temperature tempering brittleness and high temperature tempering brittleness.

After quenching martensitic structure of precision tube low temperature tempering brittle alloy steel, the steel embrittlement is made by tempering in the temperature range of 250 ~ 400℃, and the transformation temperature of toughness to brittleness is obviously increased. The embrittlement precision tube can no longer be eliminated by low temperature tempering heating, so it is also called % 26LDquo; Irreversible temper brittleness %26rdquo; . It mainly occurs in alloy structural steel and low alloy ultra-high strength precision pipe steel. The fracture of embrittlement precision tube is either intercrystalline fracture or intercrystalline and quasi cleavage fracture. The causes of low temperature tempering brittleness are generally considered as follows :(1) it is closely related to grain boundary embrittlement caused by the precipitation of cementite at the original austenite grain boundary during low temperature tempering. (2) The segregation of impurity elements such as phosphorus at the grain boundary of proto-austenite is also one of the reasons for tempering brittleness at low temperature. High purity precision tubes with phosphorus content less than 0.005% do not produce low temperature tempering brittleness. The austenite grain boundary segregation occurs when the phosphorus is heated by fire and remains after quenching. Phosphorus precipitates at proto-austenite grain boundary during segregation and cementite tempering. These two factors cause intergranular brittle fracture and contribute to the occurrence of low temperature tempering brittleness.

Alloy elements in precision tubes have great influence on tempering brittleness at low temperature. Chromium and manganese promote the segregation of impurity elements such as phosphorus at austenite grain boundaries, thus promoting low temperature tempering brittleness, tungsten and vanadium basically have no effect, molybdenum reduces the ductile-brittleness transition temperature of low temperature tempering precision tube, but it is not enough to inhibit low temperature tempering brittleness. Silicon can delay the precipitation of cementite during tempering and increase its formation temperature, so it can increase the temperature at which the brittleness of precision tube occurs at low temperature.