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Detailed introduction of American Standard 4140 alloy steel pipe

From: Shandong Baote Metal Products Co., Ltd.  DATE: 2022/4/8  Hits: 4125

Detailed introduction of American Standard 4140 alloy steel pipe

4140 Seamless Steel Pipe is rolled at recrystallization temperature. 4140 seamless Steel Pipe of China steel pipe plant: compared with cold rolling, cold rolling is rolling below the recrystallization temperature, while hot rolling is rolling above the recrystallization temperature. Advantage It can destroy the casti...

4140 Seamless Steel Pipe is rolled at recrystallization temperature.


4140 seamless Steel Pipe of China steel pipe plant: compared with cold rolling, cold rolling is rolling below the recrystallization temperature, while hot rolling is rolling above the recrystallization temperature.


Advantage


It can destroy the casting structure of ingot, refine the grain of steel and eliminate the defects of microstructure, so as to make the structure of steel dense and improve the mechanical properties. This improvement is mainly reflected in the rolling direction, so that the steel is no longer isotropic to a certain extent; Bubbles, cracks and looseness formed during pouring can also be welded under the action of high temperature and pressure.


Shortcoming


1. After hot rolling, the non-metallic inclusions (mainly sulfide, oxide and silicate) in the steel are pressed into thin sheets, resulting in delamination (interlayer). Delamination greatly deteriorates the tensile properties of steel along the thickness direction, and interlayer tear may occur when the weld shrinks. The local strain induced by weld shrinkage often reaches several times of the yield point strain, which is much larger than that caused by load;


2. Residual stress caused by uneven cooling. Residual stress is the stress of internal self phase equilibrium without external force. Hot rolled sections of various sections have this kind of residual stress. Generally, the larger the section size of section steel, the greater the residual stress. Although the residual stress is self balanced, it still has a certain impact on the performance of steel members under external force. For example, it may have adverse effects on deformation, stability and fatigue resistance.


3. The thickness and side width of hot rolled steel products are not easy to control. We are familiar with thermal expansion and cold contraction. At the beginning of hot rolling, even if the length and thickness meet the standard, there will still be a certain negative difference after cooling. The wider the edge width of this negative difference is, the thicker the thickness is, the more obvious the performance is. Therefore, for large steel, the side width, thickness, length, angle and sideline of steel can not be required to be too accurate.
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