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Performance introduction of 5120 alloy steel pipe

From: Shandong Baote Metal Products Co., Ltd.  DATE: 2022/4/12  Hits: 3809

Performance introduction of 5120 alloy steel pipe

China Shandong Baote metal products Co., Ltd China alloy Steel Pipe 5120 has a hollow section and is widely used as a pipeline for conveying fluids, such as oil, natural gas, gas, water and some solid materials. Compared with solid steel such as round steel, when the bending and torsional strength is the same, the weight is lighter. ...

China Shandong Baote metal products Co., Ltd


China alloy Steel Pipe 5120 has a hollow section and is widely used as a pipeline for conveying fluids, such as oil, natural gas, gas, water and some solid materials. Compared with solid steel such as round steel, when the bending and torsional strength is the same, the weight is lighter.


5120 steel pipe of China Steel Pipe Factory is a kind of economic section steel, which is widely used to manufacture structural parts and mechanical parts, such as oil drill pipe, automobile transmission shaft, bicycle frame and steel scaffold used in construction. Using 5120 Seamless Steel Pipe to manufacture ring parts can improve material utilization, simplify manufacturing processes, and save materials and processing hours, such as rolling bearing ring, jack sleeve, etc. at present, steel pipe has been widely used to manufacture.


5120 steel pipe is also an indispensable material for all kinds of conventional weapons. The barrel and barrel of the gun should be made of steel pipe. 5120 steel pipe can be divided into round pipe and special-shaped pipe according to different cross-sectional area and shape. Because the circular area is the largest under the condition of equal circumference, more fluid can be transported by circular pipe. In addition, when the ring section is subjected to internal or external radial pressure, the force is more uniform. Therefore, most steel pipes are circular pipes.


Chemical composition (mass fraction) (%)

C 0.18-0.24 Si 0.17-0.37 Mn 0.05-0.80 Cr≤ 0.70-1.00 Mo - Ni - B - V 


Grade of 5120 steel pipe 5120
Mechanical properties
Tensile strength MPa 835
Yield point MPa 540
Elongation after fracture (%) 10

Reduction of area (%) 40


Compared with 5115 steel, 5120 steel pipe has higher strength and hardenability. The critical hardenability diameter in oil is up to 4 ~ 22mm and in water is up to 11 ~ 40mm, but the toughness is poor. This steel still has the tendency of grain growth during carburizing, and direct quenching at lower temperature has a great impact on the impact toughness. Therefore, secondary quenching is required after carburizing to improve the toughness of the core of the part without tempering brittleness; Steel has high cold strain plasticity and can be drawn in cold state; Machinability is good in high temperature normalizing or quenching and tempering state, but poor after annealing; 20Cr is pearlite with good weldability. Generally, heat treatment is not required after welding, but the parts with thickness greater than 15mm need to be preheated to 100 ~ 150 ℃ before welding, and there can be no reflow heat treatment after welding.


Material processing 


In order to improve the wear resistance of the mold cavity, carburizing treatment is required after the mold is formed, and then quenching and low-temperature tempering are carried out, so as to ensure that the surface of 5120 steel pipe has high hardness and high wear resistance and the heart has good toughness. For molds with low service life requirements, quenching and tempering can also be carried out directly. There are also many examples of manufacturing cold working dies by strong quenching of low-carbon martensite in China.


The process route of the steel die parts: blanking - forging die blank - annealing - mechanical rough machining - cold extrusion forming - recrystallization annealing - mechanical finishing - carburizing - quenching, tempering - grinding and polishing - assembly.


Process specification for 5120 steel pipe


Normalizing specification: temperature 920-950 ℃, hardness 156-179hbs.
Specification for softening treatment of cold pressed rough embryo: the temperature is 700 ~ 720 ℃, the holding time is 8 ~ 15h, and the temperature is reduced to ≤ 550 ~ 600 ℃ with the furnace at the cooling rate of 50 ~ 100 ℃ / h. Hardness before treatment ≤ 179hbs, hardness after softening ≤ 140hbs.
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