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Precision bright steel pipe
Precision bright tube is a high-precision steel pipe material processed by precision drawing or cold rolling
Product details
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Precision bright tube is a high-precision steel pipe material that has been processed through precision drawing or cold rolling. Due to the lack of oxide layer on the inner and outer walls, high pressure resistance without leakage, high precision, high smoothness, no deformation during cold bending, expansion, flattening without cracks, etc., precision bright tubes are mainly used to produce products for pneumatic or hydraulic components, such as cylinders or oil cylinders, which can be seamless tubes or welded tubes. The chemical composition of precision bright tubes includes carbon C, silicon Si, manganese Mn, sulfur S, phosphorus P, and chromium Cr. High quality carbon steel, precision rolling, non oxidizing bright heat treatment (NBK state), non-destructive testing, special equipment brushing and high-pressure flushing of the inner wall of the steel pipe, rust proof oil treatment on the steel pipe, and dust prevention treatment on both ends of the cover.
The inner and outer walls of the steel pipe have high precision and smoothness. After heat treatment, the steel pipe has no oxide layer, and the inner wall cleanliness is high. The steel pipe can withstand high pressure without deformation during cold bending, and there are no cracks during expansion or flattening. The precision steel pipe provided by Tianjin Century Zhonglian can be used for various complex deformations and mechanical processing treatments. Steel pipe color: white with a hint of brightness, with a high metallic luster.
Main purpose:
Machinery such as automobiles and mechanical parts have high requirements for the accuracy and smoothness of steel pipes. Precision steel pipe users are not just those who require high precision and smoothness. Due to the high precision of precision bright pipes and the ability to maintain tolerances of 2-8 threads, many mechanical processing users are gradually transforming seamless steel pipes or round steel into precision bright pipes in order to save labor, material, and time losses.
Mechanical properties
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Brand number
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Delivery status
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Cold processing/hard (Y)
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Cold processing/soft (R)
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Stress relief annealing (T)
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ób≥/MPa
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δ 5≥(%)
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ób≥/MPa
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δ5≥(%)
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ób≥/MPa
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δ5≥(%)
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10
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410
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6
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375
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10
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335
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12
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20
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510
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5
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450
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8
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430
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10
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30
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590
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4
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550
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6
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520
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8
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45
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645
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4
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630
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5
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610
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7
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Temper brittleness
After quenching the precision bright tube to obtain martensitic structure, it is tempered in the temperature range of 450-600 ℃; Or tempering at 650 ℃ and then slowly cooling at a rate of 350-600 ℃; Alternatively, after tempering at 650 ℃ and long-term heating in the temperature range of 350-650 ℃, the precision bright tube may become brittle. If the already brittle 20 # precision steel tube is reheated to 650 ℃ and then rapidly cooled, its toughness can be restored, hence it is also known as% 26ldquo; Reversible temper brittleness% 26rdquo; High temperature tempering brittleness is manifested as the increase in toughness and brittle transition temperature of precision bright tubes. High temperature tempering brittleness. Sensitivity is generally expressed as the difference between the toughness brittleness transition temperature (% 26Delta; T) between the ductile and brittle states. The more severe the high-temperature tempering brittleness, the higher the proportion of intergranular fracture on the fracture surface of precision bright tubes.
The effect of elements in precision bright tubes on high-temperature tempering brittleness can be divided into: (1) impurity elements such as phosphorus, tin, antimony, etc. that cause high-temperature tempering brittleness in precision bright tubes. (2) Alloy elements that promote or mitigate high-temperature tempering brittleness in different forms and degrees. Chromium, manganese, nickel, silicon, etc. have a promoting effect, while molybdenum, tungsten, titanium, etc. have a delaying effect. Carbon also plays a promoting role. Generally, carbon precision bright tubes are not brittle during high-temperature tempering. Sensitive, binary or multicomponent alloy steels containing chromium, manganese, nickel, and silicon are very sensitive, and their sensitivity varies depending on the type and content of alloy elements.
The sensitivity of the original microstructure of tempered precision bright tubes to the high-temperature tempering brittleness of steel varies significantly. The martensitic high-temperature tempered structure is most sensitive to high-temperature tempering brittleness, followed by the bainitic high-temperature tempered structure, and the pearlite structure is the smallest.
The essence of high-temperature tempering brittleness in precision bright tubes is generally believed to be the segregation of impurity elements such as phosphorus, tin, antimony, and arsenic at the original austenite grain boundaries, leading to grain boundary embrittlement. Alloy elements such as manganese, nickel, and chromium undergo co segregation with the aforementioned impurity elements at grain boundaries, promoting the enrichment of impurity elements and exacerbating embrittlement. Molybdenum, on the other hand, has a strong interaction with impurity elements such as phosphorus, which can cause precipitation in the crystal and hinder the segregation of phosphorus at grain boundaries, reducing high-temperature tempering brittleness. Rare earth elements also have a similar effect to molybdenum. Titanium effectively promotes the precipitation of impurity elements such as phosphorus within the crystal, thereby reducing the grain boundary segregation of impurity elements and slowing down high-temperature tempering brittleness.
The measures to reduce the high-temperature tempering brittleness of precision bright tubes include: (1) rapid cooling with oil or water after high-temperature tempering to suppress the segregation of impurity elements at grain boundaries; (2) By using molybdenum containing precision bright tubes, when the molybdenum content in the steel increases to 0.7%, the tendency for high-temperature tempering embrittlement is greatly reduced. Beyond this limit, special carbides rich in molybdenum are formed in the 20 # precision steel tube, and the molybdenum content in the matrix decreases, resulting in an increase in the brittleness tendency of the precision bright tube; (3) Reduce the content of impurity elements in 20 # precision steel pipes; (4) Components that have been working in the high-temperature tempering embrittlement zone for a long time cannot be prevented from embrittlement by adding molybdenum alone. Only by reducing the impurity element content in the 20 # precision steel pipe, improving the purity of the precision bright pipe, and supplementing it with composite alloying of aluminum and rare earth elements, can we effectively prevent embrittlementWarm tempered brittleness.
1： The calculation method for determining the compressive strength of seamless bright pipes based on their outer diameter, specifications, and wall thickness (different materials of steel pipes have different tensile strengths)
Pressure=(wall thickness * 2 * tensile strength of steel pipe material)/(outer diameter * coefficient)
2： The calculation method for wall thickness of seamless steel pipes with known outer diameter and bearing pressure:
Wall thickness=(pressure * outer diameter * coefficient)/(2 * tensile strength of steel pipe material)
3： Method for expressing the pressure coefficient of seamless bright pipes:
Steel pipe pressure P<7Mpa coefficient S=8
7<steel pipe pressure P<17.5 coefficient S=6
Steel pipe pressure P>17.5 coefficient S=4
Common specification table
Specification Specification Specification Specification Specification Specification
18 * 2 23 * 3 30 * 6 38 * 2.5 50 * 2 58 * 3 68 * 3 78 * 8
10 * 2.5 23 * 4 32 * 2 38 * 3 50 * 2.5 58 * 4 68 * 4 80 * 2
16 * 2 24 * 2 32 * 2.5 38 * 3.5 50 * 3 58 * 6 68 * 6 80 * 3
16 * 2.5 24 * 3 32 * 3 38 * 4 50 * 4 59 * 2 70 * 2 80 * 4
16 * 3 24 * 4 32 * 3.5 38 * 6 50 * 6 59 * 3 70 * 3 80 * 6
17 * 2 25 * 2 32 * 4 40 * 2 51 * 2 59 * 4 70 * 4 80 * 8
17 * 2.5 25 * 3 32 * 5 40 * 3 51 * 3 59 * 6 70 * 6 80 * 12
17 * 3 25 * 4 32 * 6 40 * 4 51 * 4 60 * 2 72 * 2 81 * 2
18 * 2 27 * 2 34 * 2 40 * 5 52 * 2 60 * 3 72 * 3 81 * 4
18 * 2.5 27 * 3 34 * 2.5 40 * 6 52 * 3 60 * 4 72 * 4 81 * 6
18 * 3 27 * 4 34 * 3 42 * 2 52 * 4 60 * 6 72 * 6 81 * 8
19 * 2 28 * 2 34 * 4 42 * 3 52 * 6 62 * 2 75 * 2 81 * 12
19 * 2.5 28 * 2.5 34 * 5 42 * 4 53 * 2 62 * 3 75 * 3 82 * 4
19 * 3 28 * 3 34 * 6 42 * 6 53 * 3 62 * 4 75 * 4 82 * 6
19 * 3.5 28 * 3.5 35 * 2 45 * 2 53 * 4 62 * 6 75 * 6 82 * 8
18 * 2 23 * 3 30 * 6 38 * 2.5 50 * 2 58 * 3 68 * 3 78 * 8
10 * 2.5 23 * 4 32 * 2 38 * 3 50 * 2.5 58 * 4 68 * 4 80 * 2
16 * 2 24 * 2 32 * 2.5 38 * 3.5 50 * 3 58 * 6 68 * 6 80 * 3
16 * 2.5 24 * 3 32 * 3 38 * 4 50 * 4 59 * 2 70 * 2 80 * 4
16 * 3 24 * 4 32 * 3.5 38 * 6 50 * 6 59 * 3 70 * 3 80 * 6
17 * 2 25 * 2 32 * 4 40 * 2 51 * 2 59 * 4 70 * 4 80 * 8
17 * 2.5 25 * 3 32 * 5 40 * 3 51 * 3 59 * 6 70 * 6 80 * 12
17 * 3 25 * 4 32 * 6 40 * 4 51 * 4 60 * 2 72 * 2 81 * 2
18 * 2 27 * 2 34 * 2 40 * 5 52 * 2 60 * 3 72 * 3 81 * 4
18 * 2.5 27 * 3 34 * 2.5 40 * 6 52 * 3 60 * 4 72 * 4 81 * 6
18 * 3 27 * 4 34 * 3 42 * 2 52 * 4 60 * 6 72 * 6 81 * 8
19 * 2 28 * 2 34 * 4 42 * 3 52 * 6 62 * 2 75 * 2 81 * 12
19 * 2.5 28 * 2.5 34 * 5 42 * 4 53 * 2 62 * 3 75 * 3 82 * 4
19 * 3 28 * 3 34 * 6 42 * 6 53 * 3 62 * 4 75 * 4 82 * 6
19 * 3.5 28 * 3.5 35 * 2 45 * 2 53 * 4 62 * 6 75 * 6 82 * 8
Common Material Chemical Composition
10# 0.07~0.13 0.17~0.37 0.35~0.65 ≤0.035 ≤0.035
20# 0.17~0.23 0.17~0.37 0.35~0.65 ≤0.035 ≤0.035
35# 0.32~0.39 0.17~0.37 0.35~0.65 ≤0.035 ≤0.035
45# 0.42~0.50 0.17~0.37 0.50~0.80 ≤0.035 ≤0.035
40cr 0.37~0.44 0.17~0.37 0.50~0.80 ≤0.035 ≤0.035 0.08~1.10
25Mn 0.22~0.2 0.17~0.37 0.70~1.00 ≤0.035 ≤0.035 ≤0.25
37Mn5 0.30~0.39 0.15~0.30 1.20~1.50 ≤0.015 ≤0.020
Standard, material, delivery status
Main standards: GB/T3639，DIN2391-94/C，DIN2445，EN10305，DIN1630，DIN1629，ASTM A106，ASTM A179，JIS G3445
Main materials: 10 #, 20 #, 35 #, 45 #, 40Cr, 25Mn.37Mn5, St35 (E235), St37.4, St45 (E255), St52 (E355)
Main delivery status: NBK (+N), GBK (+A), BK (+C), BKW (+LC), BKS (+SR)
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