The Role Of Manganese In Steel And Its Influence On Heat Treatment

Manganese is a good deoxidizer and desulfurizer. Steel generally contains a certain amount of manganese, which can eliminate or weaken the hot brittleness of steel caused by sulfur, thereby improving the hot working performance of steel.

Manganese and iron form solid solution to improve the hardness and strength of ferrite and austenite in steel. It is also a carbide forming element that enters the cementite to replace some iron atoms. Manganese in steel due to lower critical transition temperature. It plays the role of refining pearlite. It also plays an indirect role in improving the strength of pearlite steel; Manganese is second only to nickel in its ability to stabilize austenitic structures and also strongly increases the hardenability of steel. A variety of alloy steels have been made with manganese of less than 2% combined with other elements.

In high carbon and high manganese wear-resistant steel. Manganese content can reach 10%-14%, good toughness after solid solution treatment, when the impact and deformation, the surface layer will be strengthened due to deformation, with high wear resistance.

Manganese and sulfur form MnS with higher melting points. Prevents thermal brittleness caused by FeS. Manganese has the tendency to increase grain coarsening and temper brittleness sensitivity of steel. If the cooling after smelting casting and forging rolling is not proper, it is easy to produce white spots in steel.

(1) The effect of microstructure and heat treatment of steel

A, manganese is a good deoxidizer and desulfurizer, industrial steel generally contains a certain amount of manganese.

B, manganese soluble in ferrite and austenite. The austenite region is enlarged, so that the critical temperature of A4 is increased, A3 is decreased, and the (α+γ) region is moved down. When the manganese content exceeds 12%, the upper critical point drops below room temperature, allowing the steel to form a single austenitic structure at room temperature. At the same time, the eutectoid temperature is reduced, and the carbon content in the eutectoid is reduced.

C, manganese strongly reduces the Ar1 and martensitic transition temperature of steel (its role is second only to carbon) and the speed of phase change in steel, improves the hardenability of steel, and increases the residual austenite content.

D, the tempered structure of the steel is uniform and refined, avoiding the aggregation of carbides in the carburizing layer, but increasing the overheating sensitivity and tempering brittleness tendency of the steel.

E, manganese is a weak carbide forming element.

(2) Effect on mechanical properties of steel

A. The effect of manganese on strengthening ferrite or austenite is less than that of carbon, phosphorus and silicon, which has no effect on ductility while increasing strength.

B, because the pearlite is refined, the strength of low carbon and medium carbon pearlite steel is significantly improved, and the ductility is reduced.

C, by improving the hardenability and improve the mechanical properties of tempered sortensitic steel.

D, under the premise of strict control of heat treatment process, avoid overheating grain growth and temper brittleness, manganese will not reduce the toughness of steel.

(3) The effect on the physical, chemical and technological properties of steel

A. With the increase of manganese content, the thermal conductivity of steel decreases sharply, and the linear expansion coefficient increases, so that the internal stress is formed during rapid heating or cooling, and the cracking tendency of the workpiece increases.

B, the electrical conductivity of the steel decreases sharply, the resistivity increases correspondingly, and the resistance temperature coefficient decreases.

C, the coercive force increases, saturation magnetic induction, residual magnetic induction and permeability are reduced, so manganese is beneficial to permanent magnet alloy and harmful to soft magnetic alloy.

D, when the manganese content is high, the oxidation resistance of the steel decreases.

E, the sulfur in the steel to form a higher melting point of MnS, to avoid the FeS film on the grain boundary, eliminate the hot brittleness of the steel, improve the hot processing performance.

F, high manganese austenitic steel deformation resistance is larger, and the ingot columnar crystallization is obvious, more easy to crack during forging and rolling.

G. Due to improved hardenability and reduced martensitic transition temperature, it has an adverse effect on welding performance. Carbon content should be reduced to an appropriate extent.

(4) Application in steel

A. There is often an appropriate amount of manganese and phosphorus in the free-cutting steel, and MnS inclusions make the chips easy to break.

B, the use of manganese in ordinary low-alloy steel to strengthen ferrite and pearlite, improve the strength of steel, manganese content is generally 1%-2%.

Many series of C, carburized and tempered alloy structural steels contain no more than 2% manganese.

D, the use of manganese in spring steel, bearing steel and tool steel to strongly improve the role of hardenability, can use oil quenching and air cooling quenching process to reduce cracking, distortion and deformation.

E, wear-resistant steel, non-magnetic steel, stainless steel, heat-resistant steel, including high carbon and high manganese wear-resistant cast steel (C: 1.0%-1.4%, Mn: 10%-14%), medium carbon high manganese non-magnetic steel (C: 0.3%-0.6%, Mn: 18%-19%), low carbon high manganese stainless steel (Cr, no Ni or less Ni), High manganese heat resistant steel (heat resistant non-peeling steel with Mn instead of Ni, or containing Al, Mo, V, etc.).

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CANGZHOU GALAXY STEEL PIPE CO., LTD

Precision Bright Pipes

 Precision bright pipe is a kind of ordinary seamless steel pipe (or de-diameter welded steel pipe) through fine drawing or cold rolling processing of a high-precision steel pipe material. Because there is no oxide layer on the inner and outer walls of the precision bright pipe, no leakage under high pressure, high precision, high finish, cold bending without deformation, flaring, flattening without cracks, etc., it is mainly used to produce products of pneumatic or hydraulic components, such as cylinders or cylinders, which can be seamless pipes and welded pipes.

The chemical composition of the precision bright tube is carbon C, silicon Si, manganese Mn, sulfur S, phosphorus P, chromium Cr. The inner wall of the steel pipe is cleaned by special equipment and washed under high pressure, the anti-rust oil on the steel pipe is treated as anti-rust, and the caps at both ends are treated as dustproof. High precision and high finish of the inner and outer walls of the steel pipe, no oxide layer after heat treatment, high cleanliness of the inner wall, steel pipe under high pressure, cold bending without deformation, flaring, flattening without cracks. Precision steel pipe can be used for a variety of complex deformation and mechanical processing. Steel pipe color: white with bright, with high metallic luster.

Precision bright pipe main application:

Automobiles, mechanical parts, etc., have high requirements for the precision and finish of steel pipes. Precision steel pipe users are not only users with high precision and finish requirements, because of the high precision of the precision bright pipe, the tolerance can be maintained at 2-8 wires.

The influence of elements in precision bright tubes on high temperature tempering brittleness:

(1) Impurity elements such as phosphorus, tin, antimony, etc. that cause high temperature tempering brittleness of precision bright tubes.

(2) Alloying elements that promote or slow down high-temperature tempering brittleness in different forms and to different degrees. Chromium, manganese, nickel, silicon and so on play a promoting role, while molybdenum, tungsten, titanium and so on play a delaying role. Carbon also plays a catalytic role.

General carbon precision bright tubes are not sensitive to high temperature tempering brittleness, and binary or multiple alloy steels containing chromium, manganese, nickel and silicon are very sensitive, and their sensitivity varies according to the type and content of alloying elements.

The sensitivity of the original structure of the tempered precision bright pipe to the high temperature tempering brittleness of steel is significantly different. The sensitivity of martensite high-temperature tempering structure to high-temperature tempering brittleness is the highest, followed by bainite high-temperature tempering structure, and pearlite structure is the least.

The nature of high temperature tempering brittleness of precision bright pipes is generally believed to be the result of the segregation of impurity elements such as phosphorus, tin, antimony and arsenic at the grain boundaries of the original austenite, resulting in the embrittlement of the grain boundaries. The co-segregation of manganese, nickel, chromium and other alloying elements at the grain boundary promotes the enrichment of impurity elements and intensifies the embrittlement. Molybdenum, on the contrary, has a strong interaction with impurity elements such as phosphorus, which can produce a precipitated phase in the crystal and hinder the grain boundary segregation of phosphorus, and can reduce high temperature tempering brittleness rare earth elements also have a similar effect with molybdenum. Titanium can more effectively promote the precipitation of impurity elements such as phosphorus in the crystal, thus weakening the grain boundary segregation of impurity elements and slowing down the high temperature tempering brittleness.

The measures to reduce the high temperature tempering brittleness of precision bright pipe are:

(1) Oil cooling or water rapid cooling after high temperature tempering to inhibit the segregation of impurity elements in the grain boundary;

(2) The use of molybdenum containing precision bright tube species, when the molybdenum content in the steel increases to 0.7%, the high temperature tempering embrittlement tendency is greatly reduced, more than this limit 20# precision steel pipe formed a special carbide rich in molybdenum, molybdenum content in the matrix decreases, the embrittlement tendency of precision bright tube increases;

(3) Reduce the content of impurity elements in the precision steel pipe;

For the parts working in the high-temperature tempering embrittlement zone for a long time, it is difficult to prevent embrittlement with molybdenum alone. Only by reducing the content of impurity elements in the precision steel pipe, improving the purity of the precision bright pipe, and supplemented by the composite alloying of aluminum and rare earth elements, can the high-temperature tempering embrittlement be effectively prevented.

Precision bright pipe standards:

China: GB/T3639, Germany: DIN2391, DIN2393, DIN2445, EU: EN10305, Germany: DIN1630, DIN1629, USA: ASTM A519, Japan: JIS G3445.....

Steel grade:

10#, 20#, 35#, 45#, 40Cr, 25Mn, 37Mn5, St35(E235), St37.4, St45(E255), St52(E355) 30CrMo, 42CrMo, 4130, 4140.......

Main delivery status:

NBK(+N), GBK(+A), BK(+C), BKW(+LC), BKS(+SR)

After the martensitic structure is obtained by quenching the precision bright tube, it is tempered in the temperature range of 450 ~ 600℃; Or at 650℃ after tempering at a slow cooling rate of 350 ~ 600℃; Or after tempering at 650 ° C, long-term heating in the temperature range of 350 ~ 650 ° C will cause embrittlement of the precision bright tube. If the already brittle precision steel pipe is reheated to 650 ° C and then quickly cooled, the toughness can be restored. The high temperature tempering brittleness is manifested as the increase of the toughness and brittleness transformation temperature of the precision bright pipe. Sensitivity is generally expressed as the difference between the toughness and brittleness transition temperature of the toughening state and the embrittlement state. The more serious the tempering brittleness at high temperature, the higher the proportion of the fracture of the precision bright pipe is.

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CANGZHOU GALAXY STEEL PIPE CO., LTD

Accu-Roll Seamless Tube Rolling Machine

 

Accu-Roll tube rolling machine started in Yantai Lubao, Chengdu and other places in the early 1990s in China, which was noisy at that time and had the momentum of replacing other diagonal rolling and continuous rolling units, but after practice test, Because of the short length of the rolled seamless pipe, the production of some specifications of 3 times the length of the pipe is limited, and the deep spiral print on the surface of the pipe when rolling thin wall pipes affects the appearance and quality of the steel pipe, so far it has only survived in China, especially in the recent past, some private enterprises have built a number of small Accu-Roll tube rolling units, and there have been no reports of foreign construction of this type of tube rolling machine. This machine is not suitable for the production of large and medium caliber seamless steel pipe. It is actually a two-high horizontal long mandrel skew mill with active guide plate.

The mill structure has the following characteristics:

The two rolls are tapered. As with the conical roll piercing machine, there are feeding Angle and rolling Angle, so that the diameter of the roll gradually increases along the rolling direction, which is conducive to reducing sliding, promoting the longitudinal extension of the metal and reducing the additional torsion deformation.

Two large diameter active guides are used.

The operation mode of limited movement mandrel is adopted.

The use of non-shoulder roll roll shape overcomes the concentration of wall reduction in the shoulder part of ASSEL, which reduces the roll life and wall equalization effect, thereby improving the wall thickness accuracy of the pipe.

CANGZHOU GALAXY STEEL PIPE CO., LTD

 

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Seamless Steel Pipe Is Produced By PipeJacking Method

 The pipe jacking method for the production of seamless steel pipes was proposed as early as 1892 by Heinrich Erhard in Germany. The perforation process of the initial pipe jacking unit was hydraulic perforation method. The steel ingot placed in the mold was extruded into a capillary tube with cup bottom by a vertical hydraulic press, and then the capillary tube was removed by a crane, put down, and the cup-shaped capillary tube was placed on a long mandrel, and the mandrel was pushed to reduce the diameter, reduce the wall and extend the cup-shaped capillary tube through a group of circular die holes with decreasing diameter. The power of deformation is concentrated in the tail of the ejector rod. 

It is necessary to remove the rod after the pipe jacking, and then cut the bottom of the cup, which is characterized by low productivity, serious uneven wall thickness, and limited L/D of the steel pipe. At present, this method is only used to produce large caliber (400 ~ 1400m seamless steel pipe). Another method, known as the CPE method, is to produce the tube by the diagonal rolling perforation method, and the method of shrinking the tube at one end to provide the tube for the pipe jacking machine. It can improve the yield and product quality, and restore the vitality for the production of small-caliber seamless steel pipes in the pipe jacking process.

The advantages of pipe jacking method are:

1) Less investment, simple equipment and tools, and low production cost.

2) The extension of the pipe jacking unit is large, and the number of equipment and tools required for rolling similar products can be less.

3) Wide range of variety specifications.

Cangzhou Galaxy Steel Pipe Co., Ltd

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Introduction to Hot Extruded Seamless Steel Ppe

Extrusion method refers to the metal billet is placed in a "closed" container composed of an extrusion cylinder, an extrusion die and an extrusion rod, and the pressure exerted by the extrusion rod forces the metal to flow out of the extrusion die hole, and the metal plastic forming method is obtained, which is a time-rich seamless steel pipe manufacturing method. According to the relative relationship between the direction of force applied by the extrusion rod and the direction of metal flow, the extrusion method can be divided into two kinds: positive extrusion and reverse extrusion. The direction of force applied by positive extrusion is consistent with the direction of metal flow, and the reverse extrusion is opposite. Reverse extrusion has the advantages of small extrusion pressure, large extrusion ratio, fast extrusion speed, reducing extrusion temperature, improving extrusion conditions, easy to achieve isothermal/isobaric/isobaric extrusion, improving product microstructure and dimensional accuracy, reducing metal pressure margin at the end of extrusion, improving metal yield, etc. However, its operation is relatively inconvenient, and the section size of the product is limited by the size of the extrusion rod.

The application of metal extrusion technology in industry has more than 100 years of history, but the use of steel hot extrusion technology in production was gradually developed after the invention of glass extrusion lubricant in 1941, especially the development of non-oxidation heating, high-speed extrusion technology, mold materials, and advances in tension reduction technology, making the production of seamless steel pipes more economical and reasonable. The output and quality have been greatly improved, and the range of varieties has been further expanded, thus attracting the attention of all countries.

At present, the product range of seamless steel pipe produced by extrusion method is generally: outer diameter: 18.4 ~ 840mm, the minimum wall thickness can reach 2mm, the length is about 15m, and the small diameter pipe can get 60m steel pipe. The capacity of the extrusion machine is generally 2000 ~ 4000 tons, and the maximum is 12000 tons.

Extruded seamless steel pipe production has the following advantages over other hot rolling methods:

Because the extruded metal is in a state of three-way compressive stress, it can produce materials that are difficult or unrollable and forging, such as nickel-based alloys.

Due to the large amount of metal deformation during extrusion (extrusion ratio is large), the complete deformation is completed in a short time, so that the organization of the product is uniform and the performance is good.

The internal and external surface defects are less, and the geometric size accuracy is higher.

Flexible organization and production, suitable for small batch, multi-variety production.

Can produce complex section pipe and bimetal composite pipe.

For the production of special purpose steel pipe products, such as nuclear industry, aerospace and so on

The disadvantages are:

1) High requirements for lubricants and heating, resulting in increased production costs.

2) Low tool life, large consumption, and expensive.

3) The qualified rate of finished products is low

CANGZHOU GALAXY STEEL PIPE CO., LTD

 

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S355J2 Low Alloy High Strength Steel Plate Introduction

https://www.friend-steelpipes.com/show-16-64-1.html1. Brand introduction

S355J2 is a low alloy high strength steel, S355J2 is the European standard: EN10025, can do Z-15, Z-25, Z-35 and I, II, III level of inspection requirements.

2. S355J2 Extension brand

S355J2 extension brand S355J2,S355J2-Z35,S355J2 +N-Z35,S355J2-Z35 is S355J2 based on the increase of steel plate thickness direction performance requirements, that is, Z-direction performance. S355J2+N-Z35 is a heat treatment process that increases Z-direction properties and normalizing rolling (or normalizing).

3. Chemical composition of S355J2

C: 0.15 0.18%, Si: 0.30 0.50%, Mn: 1.30 1.50%, P 0.015% or less, S 0.004% or less, Cr 0.30% or less, Ni 0.50% or less, Mo acuities were 0.10%, Cu 0.30% or less, 0.15% or less V, Nb 0.05% or less, Ti 0.05% or less The allowance is Fe and unavoidable impurities. Use thickness :125-150mm.

4. Analysis of mechanical properties of S355J2

Yield strength Rp0.2≥275MPa, tensile strength Rm:450 ~ 600MPa, elongation A≥18%,-20 impact work KV2≥47J, steel plate thickness direction tensile section shrinkage Z≥35%, the production of steel plate internal quality, high density and stable performance.

S355J2-Z35 Meaning :J2 requires -20 degree impact, Z35 is the Z-direction performance of steel plate.

The meaning of S355J2+N-Z35 :J2 requires -20 degrees of impact, N means that it is equivalent to normalizing rolling and not that it must be normalized, but a method of naming the steel number in the standard,Z35 is the Z-direction performance of the steel plate.

S355k2+N meaning :K2 requires negative 20 degree impact,J2 requires negative 20 degree impact,N means equivalent to normalizing rolling rather than must normalize.

5. Production process of S355J2 steel plate

Steel plate production methods include steelmaking, heating, rolling and normalizing processes; The steel rolling process adopts the shape control rolling process. Rolling process, ingot rolling temperature 1000 ~ 1050; The first stage adopts low speed and high pressure rolling process, the high temperature stage is 950 ~ 1000, the rolling speed is 1.6 ~ 2.0m/s, the single pass reduction rate is 15 ~ 20%, the cumulative reduction rate is 40 ~ 45%, to ensure sufficient deformation of the ingot. The opening temperature of the first stage is 910 ~ 930, the final rolling temperature is less than 870. 1, the steelmaking process, the use of electric furnace +LF furnace combined smelting process,VD vacuum treatment process to ensure that the vacuum degree ≤66Pa, vacuum holding time of 20 ~ 25min, after breaking into steel ingot. 2, heating process, ingot heating in soaking furnace, the maximum heating temperature 1270, soaking section temperature 1250 ~ 1260, to ensure uniform heating inside and outside the ingot. 3, normalizing process, the steel plate in the car furnace normalizing, steel plate normalizing temperature 880 ~ 910, holding time 1.8 ~ 2.2min/mm, that is, to get the required S355J2+N-Z35 steel plate.

6, S355J2 steel plate implementation standard

S355J2 steel plate product standard reference EN10025-2; Product performance test method standards refer to EN10025.

7, S355J2 steel plate specifications

Specification: Thickness :8-500mm, width :1600-4020mm, length :6000-18800mm.

8. Applicationof S355J2

S355J2 is a European standard structural steel, mainly used in large machinery manufacturing, equipment base, large welded steel structure, construction, bridge and other fields. With the continuous development of the economy and the large-scale needs of equipment, the demand for ultra-thick structural steel plates has gradually increased, and the technology of steel plates is becoming more and more strict, while the added value of steel plates is relatively high, especially the production of ultra-thick steel plates is relatively difficult. To achieve the production of ultra-thick steel plate, the use of ingot production in the rolling process of grain distribution, eliminate the pores in the steel plate, shrinkage and other defects, to meet the strength and impact toughness of the good match, thickness direction performance is better, suitable for mass production.

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The Cause of Uneven Thickness of Seamless Steel Pipe

 Seamless steel pipe precision steel pipe finished products will have the problem of uneven thickness, but how is it produced?

The uneven thickness of seamless steel pipe is mostly generated during hot perforation:

According to the anatomical analysis of the steel pipe rolled by the automatic tube rolling machine, we believe that the uneven wall thickness of the perforated tube basically retains the distribution characteristics of the uneven wall thickness of the perforated tube, that is, the steel pipe still has a spiral wall uneven thickness after rolling, and the transverse wall uneven thickness increases significantly.

The causes of uneven wall thickness in automatic tube rolling machines are:

① The existence form and severity of the uneven wall thickness of perforated tube directly affect the existence form and severity of the uneven wall thickness of rolled steel tube.

(2) In the automatic pipe rolling machine, the wall thickness is uneven due to the bending of the top rod, so that the top head position deviates from the center of the pass, and the maximum wall thickness and minimum wall thickness positions on each cross section of the pipe and the pipe head are almost fixed; Therefore, reducing the residual curvature of the ejector rod and reducing the axial force of the ejector rod during the rolling process has a significant effect on reducing the wall thickness heterogeneity.

(3) The greater the amount of wall reduction, the more serious the uneven wall thickness of the pipe, the smaller the amount of wall reduction, the automatic tube rolling machine has the effect of reducing the uneven wall thickness of the perforated tube.

④ The pass adjustment is not correct, and when the roll seam is uneven, the uneven wall thickness of the pipe will be aggravated.

In our seamless steel pipe factory, the measured wall thickness data of Φ400mm automatic rolling pipe unit, perforation, secondary perforation (extension), automatic rolling pipe and leveling four rolling processes were carried out by Fourier transform, and the quantitative analysis of the uneven wall thickness and its formation reasons were obtained, and on this basis, the ways to improve the uneven wall thickness of steel pipe were put forward:

The uneven distribution of spiral wall thickness on the pipe after secondary perforation (extension) has been retained to the finished pipe, so improving the secondary perforation (extension) is the key link to improve the wall thickness accuracy of the finished pipe, the main measure is to improve the tool design, and improve the concentricity of the top rod and the top head in the rotation process and the rolling line.

② Improving the uneven wall thickness of the tube after perforation is an important link, the main measures are to improve the heating uniformity of the tube billet, improve the accuracy of the centering hole, lengthen the length of the top uniform strip and the length of the counter cone, and improve the concentricity of the top rod and the top head in the rotation process and the rolling line.

(3) Although the symmetric wall thickness is serious when rolling the pipe, it has a certain effect on reducing the spiral wall thickness. Therefore, when rolling the pipe, two passes should be rolled, and the waste pipe should be turned 90° between passes.

(4) The leveling process can basically eliminate the symmetrical wall thickness imbalance, but the effect on eliminating the spiral wall thickness imbalance is very small, therefore, the ability of the leveling machine should be improved.

⑤ Fourier transform is an effective means to study the uneven wall thickness during the skew rolling process, and this method can also be used to study the uneven wall thickness of other steel pipe production units.

Any factor that damages the geometry correctness of the deformation zone formed by the roll, head and guide will aggravate the uneven thickness of the pipe wall.

(1) Punch head.

① The shape design of the top, the ideal top rolling cone should be parallel to the roll exit cone, if the design of the top according to the traditional Matvikov formula, the top rolling cone and the roll exit cone are not parallel, the metal deformation in such a gradually expanding gap, is bound to cause insufficient tube wall rolling and lead to uneven tube wall thickness, and, The uneven capillary wall thickness becomes more serious with the increase of feed Angle.

(2) Because the stiffness of the ejector rod is not enough, it is bent during the perforation process, so that the ejector head can not maintain the alignment position, so that the wall thickness of the perforated capillary is uneven;

③ Uneven wear or damage of the top.

(2) Guide plate.

① The guide distance is too large, in the process of perforation is to rely on the limited role of the guide to maintain the center line of the perforation, the guide distance is large, the top change in the upper and lower position, so that the top is unstable, resulting in uneven capillary wall thickness.

The uneven wear of the upper and lower guide plates will also exacerbate the uneven wall thickness.

(3) Roll.

1 Roll center line deflection: In the production process, due to the incorrect installation of the screw on both sides of the perforator, or due to thread and bearing wear, the axial deflection between the two rolls occurs horizontally, and the feed Angle of the two rolls distorts the deformation area, resulting in uneven wall thickness.

② The large feeding Angle causes the top head to be more parallel to the rolling cone of the roll.

③ Improper roll speed will also affect the wall thickness accuracy.

(4) Centering and heating of tube billet.

Centring hole eccentricity and uneven heating will cause uneven wall thickness.

(5) Stiffness, structure and adjustment of the perforator.

The stiffness of the body of the piercing machine is not enough, and the locking mechanism on it is not reliable; The centring device of the ejector rod is not adjusted accurately, the operation is not reliable and the distance from the fuselage is too far; The adjustment of the rolling center line is generally lower than the middle line of the rolling mill, which aims to improve the stability of the rolled parts. If the adjustment is too large, the relative relationship between the tools in the deformation zone will change asymmetrically due to the rolling line moving, and the uneven wall thickness of the capillary will also be affected.

CANGZHOU GALAXY STEEL PIPE CO., LTD

 

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How to Choose Seamless Steel Pipe Correctly

Seamless steel pipe is a kind of steel pipe without weld which is manufactured by hot processing method such as perforation hot rolling. When necessary, the hot-worked pipe can be further cold worked to the desired shape, size and performance.

(1) Carbon steel seamless steel pipe material grade:

10#, 20#, 09MnV, 16Mn, 20G,GR.B, X52, X65, etc

Applicable standards:

GB8163 "Seamless Steel Pipe for Fluid Transportation"

GB/T9711 "Oil and Gas industry steel pipe delivery technical conditions"

GB6479 "High Pressure seamless steel pipe for fertilizer Equipment"

GB9948 Seamless Steel Pipe for Petroleum Cracking

GB3087 "Seamless steel pipe for Low and medium pressure boiler"

GB/T5310 "Seamless steel pipe for high-pressure boilers"

Scope of application: Designed temperature less than 350℃, pressure less than 10MPa of oil, oil and gas and public media.

Material grade: 10#, 20G, 16Mn, GR.B, X52, X65, etc.

Scope of application: low and medium pressure boiler superheated steam, boiling water, etc.

Material grade: 20G, etc.

(2) low alloy steel seamless steel pipe

Petrochemical production equipment, commonly used chromium molybdenum steel and chromium molybdenum vanadium steel seamless steel pipe standards are

GB9948 Seamless Steel Pipe for Petroleum Cracking

GB6479 "High Pressure seamless steel pipe for fertilizer Equipment"

GB/T5310 "Seamless steel pipe for high-pressure boilers"

(3) Stainless steel seamless steel pipe

Commonly used stainless steel seamless steel pipe standards are:

GB/T14976, GB13296, GB9948, GB6479, GB5310 a total of five standards. Among them, only two or three stainless steel material grades are listed in the last three standards, and they are not commonly used material grades.

Therefore, when the stainless steel seamless steel pipe standard is selected in the project, GB/T14976 and GB13296 standards are basically selected.

Stainless steel material grade: 304, 304L, 316, 316L, etc., suitable for the transport of general fluids.

GB13296 "Stainless Steel seamless steel pipe for boiler and heat exchanger" :

304L, 316L has excellent corrosion resistance, under certain conditions, can replace stable stainless steel (321, 347) for corrosion resistance to the medium; The high temperature mechanical properties of ultra-low carbon stainless steel are low, and it is generally only used under the condition of temperature below 525℃; Stable austenitic stainless steel has good corrosion resistance and high temperature mechanical properties, but the Ti in 321 is easy to be oxidized and lost in the welding process, thereby reducing its corrosion resistance, its price is higher, this kind of material is generally used in more important occasions, 304, 316 has general corrosion resistance, cheap, so it is widely used.

CANGZHOU GALAXY STEEL PIPE CO., LTD

 

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The Birth History of China's First Seamless Steel Pipe

 Seamless steel pipe is known as the "blood vessel" of industry, is an important raw material for national industrial construction and national defense construction, whether it is the manufacture of aircraft, ships, trains, automobiles, boilers, or oil, steam, water, or the development of mineral deposits for geological drilling, where it is needed, where it is inseparable. It can be said that if you leave the seamless steel pipe, many industrial development such as petroleum, chemical, steel, machinery, military, aerospace and other industries will be out of the question.

In the early years of 1949, China could not produce seamless steel pipes. At that time, only Shanghai had a little steel pipe transformation equipment, but due to the lack of hot perforating machinery, it could not use round steel to produce seamless steel pipes, and it could not import capillary pipes from abroad, and it could only use imported or used old seamless steel pipes to change into other specifications of seamless steel pipes. Due to the economic blockade and embargo imposed by the Western hostile countries on the new China, the source of seamless steel pipes imported from abroad was interrupted, and at that time, the domestic production could not be produced, which had a serious impact on the recovery of the economy and the defense industry. From August 1952 to May 1953, China sent 40 people to the first Ural new steel pipe factory in the former Soviet Union to study. With the help of Soviet experts, the workers overcame technical difficulties.

On October 27, 1953, almost all the workers arrived at the factory early, nervous and excited. On this day, China's metallurgical history will open a new page. At 2:30 in the afternoon, the whistle ordering the hot test rolling sounded, the red billet was spit out of the 1200 degree high temperature heating furnace, and the hot red steel pipe head was just exposed in the piercing machine, and people cheered: "Out!" It's coming out! The pole is out!" All the people present applauded and cheered for this historic moment of rolling seamless steel pipes in New China. The steel pipe with sparks smoothly through the mill, another round of applause and cheers, until the first steel pipe to the last process. At this time, a Soviet expert shook hands with the workers present and said: "New China has its own seamless steel pipe from today!" Gu Fengfu, a young worker who had been to the Soviet Union to learn seamless steel pipes, said excitedly: "He will immediately write a letter to the Soviet teacher who taught him the technology." Another worker said: "When he goes home, he will also tell the farmers in the countryside that they and the people of the whole country have not supported Angang's construction in vain."

On October 27, 1952, the first tube billet test rolled out a seamless steel pipe finished product, which is also a miracle in the international seamless steel pipe business. Since then, the new China has its own industrial veins.

Anshan Steel seamless steel pipe plant put into operation, the end of China can not produce seamless steel pipe history. From the factory broke ground to the first seamless steel pipe came out, it only took 1 year and 3 months. The second year after production, it has been tested out, boiler tube, geological pipe, oil pipe and stainless steel pipe. The success of rolling stainless steel pipe on the two-high skew piercing machine is a great event in the history of seamless steel pipe production in our country, which plays a forerunner for the future production of stainless steel pipe in our country.

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