The whole process intelligent one-key casting steel system

 The whole process intelligent one-click casting steel system truly realizes the whole process from the continuous casting rotary table to the billet generation, and the entire casting process only needs the remote monitoring of the operator in the operation room.

On-site steel pouring process: From the ladle into the rotary table, the vision + laser sensor will automatically identify the status of the driving coupler, and then the robot will automatically install the cylinder, the rotary table will automatically rotate, the roaster will automatically lift, the car will automatically walk and align. At the same time, the sorting robot carries out the covering agent sorting work in an orderly manner, the casting robot carries out the position scanning preparation with the scanning gun, the intelligent operating arm is ready to carry out the long nozzle sleeve joint with the long nozzle, the intelligent operating arm and the casting robot cooperate to complete the bottom nozzle scanning and the long nozzle sleeve joint operation, and the automatic pouring system controls the automatic pouring of the casting machine. Coupled with robot automatic temperature sampling, automatic slag detection, online electric width adjustment... Various intelligent equipment instead of manual production operations, orderly completion of the whole process of automatic steel pouring.

The application of intelligent one-key casting technology significantly reduces the labor intensity of workers and improves the safety of operation. This technology makes the operation process more standardized, especially in the tundish nozzle alignment link, and its high accuracy effectively improves the quality of the casting billet. At the same time, through the online mold thermal width adjustment function, there is no need to stop the operation, and the production preparation time is shortened by one hour, which not only improves the production efficiency, but also reduces the cutting loss of the blank head and the blank tail. Highly intelligent systems give steel mills a competitive advantage.

Email: sale@galaxy-steel.com

 

Wechat: LXF13931739696.  Whatsapp: 008613931739696

 Website: www.friend-steelpipes.com  www.galaxy-steel.com  www.cz-steelpipe.com

 CANGZHOU GALAXY STEEL PIPE CO., LTD

 My company hot sale seamless steel pipes:

 ASTM A106 B seamless pipes,（1” to 24” sch40, sch80),

API 5L GR.B steel pipes, (seamless pipe, 1” to 30” sch 40, sch80),

Boiler tubes,( 20G. 12Cr1MoVG, ASTM A335 P5, P9, P11),

ASTM A333 GR.6 seamless pipes, ( 1” to 24” sch40, sch80, sch160),

Precipitation behavior of carbide and nitride in duplex stainless steel and its influence

 The precipitation behavior of carbide and nitride in duplex stainless steel has significant influence on its properties. There are mainly two types of carbides, M7C3 and M23C6, among which M7C3 precipitates along the phase boundary of ferrite and austenite in the temperature range of 950~1050℃, while M23C6 precipitates faster at lower than 950℃, especially at 800℃, M23C6 precipitates in 2507 steel less than 1 minute. The precipitation of M23C6 consumes ferrite and leads to the formation of secondary austenite structures. The nitrides are mainly Cr2N and CrN, among which Cr2N precipitates more in the ferritic phase, especially in the case of rapid cooling after high temperature solution, the amount of nitride precipitates increases. Although the nitride precipitates less in the welding heat affected zone, it has little effect on the toughness and corrosion resistance of the steel.

There are mainly two types of carbide precipitated phase: M7C3 and M23C6. In the duplex stainless steel with relatively high carbon content (≥0.03%), M7C3 carbides will be precipitated along the two-phase boundary of ferrite and austenite during thermal treatment in the temperature range of 950~1050℃. In the heat treatment at a temperature below 950℃, M23C6 carbide will be precipitated along the two-phase boundary, and its precipitation speed is very fast, such as 2507 steel at 800℃, its M23C6 carbide precipitation time is less than 1min, even if the rapid cooling method is difficult to avoid the generation of this carbide. It is first produced at the two-phase boundary of ferrite and austenite, and then precipitated at the grain boundary of ferrite and austenite, but it does not occur in ferrite and austenite. During the growth of M23C6 grains, the ferritic content of the neighboring region will be consumed, which leads to the transformation of the original ferritic region into secondary austenite structure, thus forming the aggregation region of M23C6 and γ phases.

There are two types of nitride precipitated phases, Cr2N and CrN, of which Cr2N is the most important precipitated form. Cr2N usually also contains Fe and Mo elements, but is structurally a type M2N nitride. 2507 type two-phase stainless steel after high temperature solid solution into water, Cr2N precipitation will occur at the grain boundary of the ferritic phase and inside the grain, mainly because the solubility of nitrogen in the ferritic phase is relatively low, and the N element is susaturated, so it will be easy to precipitate nitrogen in the case of rapid cooling, and the higher the temperature of solid solution, The amount of precipitation will also increase. It is found in the heat affected zone of 700-900 welded joints, and the precipitation of such nitrides is relatively rare, and the influence on the toughness and corrosion resistance of steel is not significant in general.

Email: sale@galaxy-steel.com

 

Wechat: LXF13931739696.  Whatsapp: 008613931739696

 

Website: www.friend-steelpipes.com  www.galaxy-steel.com  www.cz-steelpipe.com 

CANGZHOU GALAXY STEEL PIPE CO., LTD

 My company hot sale steel pipe and pipe fittings:

 ASTM A106 B seamless pipes,（1” to 24” sch40, sch80),

API 5L GR.B steel pipes, (seamless pipe, LSAW pipe, SSAW pipes, 1” to 110” sch 40, sch80),

Boiler tubes,( 20G. 12Cr1MoVG, ASTM A335 P5, P9, P11),

ASTM A333 GR.6 seamless pipes, ( 1” to 24” sch40, sch80, sch160),

TP304/304L, TP316/TP316L, stainless steel pipes, (1” to 48” sch10, sch20, sch40, sch80) 

SSAW welded line pipes API 5L X70 PSL2 36" STD UT test on line

China Reliable Steel pipe manufacturer and supplier

China Reliable Steel pipe manufacturer and supplier

Stainless steel welded pipe weld seam corrosion overview

 Stainless steel welded pipe weld seam corrosion overview

Corrosion of welded joints, usually occurring in stainless steel pipes, has three forms of corrosion.

① The welding seam is corroded into a spongy shape, which is the δ ferrite selective corrosion of austenitic stainless steel.

In order to improve welding performance, austenitic stainless steel usually requires the weld to contain 3% to 10% ferrite structure, but in some highly corrosive media will occur δ ferrite selective corrosion, that is, corrosion occurs only in the δ ferrite phase (or further decomposition into σ phase), the result is spongy.

② Heat affected zone corrosion. The reason for this corrosion is that the temperature here is just in the sensitized zone during the welding process, and there is sufficient time to precipitate the carbide, resulting in intergranular corrosion.

Intergranular corrosion is a kind of corrosion form where the corrosion is limited to and near the grain boundary and the grain itself is relatively small, which will cause the grain to fall off or reduce the mechanical strength of the material.

The mechanism of intergranular corrosion is "chromium deficiency theory". Stainless steel has high corrosion resistance due to chromium, and its chromium content must exceed 12%, otherwise its corrosion resistance is similar to ordinary carbon steel. In the sensitization temperature range of stainless steel (450 ~ 850℃), the susaturated solid solution carbon in austenite will be combined with chromium to form Cr23C6 and precipitate along the grain boundaries. Because the diffusion rate of chromium in austenite is slower than that of carbon, the lead required for the formation of Cr23C6 must be obtained from near the grain boundary, resulting in chromium deficiency near the grain boundary. If the chromium content is reduced to 12% (the limit of chromium content required for passivation) below, the chromium-poor region is in an activated state, as an anode, it forms a corrosion galvanic cell between the grain, the anode area of the chromium-poor region is small, and the cathode area of the grain is large, resulting in serious corrosion of the chromium-poor region near the grain boundary.

③ knife-edge corrosion at the fusion line generally occurs in stainless steel (347 and 321) stabilized with Nb and Ti. Knife-edge corrosion mostly occurs in oxidizing media.

Email: sale@galaxy-steel.com

 

Wechat: LXF13931739696.  Whatsapp: 008613931739696

 

Website:  https://www.friend-steelpipes.com/  https://www.cz-steelpipe.com/

 

CANGZHOU GALAXY STEEL PIPE CO., LTD

 

China Reliable Steel Pipe and Pipe Fittings Manufacturer and Supplier

My company hot sale steel pipe and pipe fittings:

 

ASTM A106 B seamless pipes,（1” to 24” sch40, sch80),

API 5L GR.B steel pipes, (seamless pipe, LSAW pipe, SSAW pipes, 1” to 110” sch 40, sch80),

Boiler tubes,( 20G. 12Cr1MoVG, ASTM A335 P5, P9, P11),

ASTM A333 GR.6 seamless pipes, ( 1” to 24” sch40, sch80, sch160),

TP304/304L, TP316/TP316L, stainless steel pipes, (1” to 48” sch10, sch20, sch40, sch80),

API 5L X65, X70 PSL2 LSAW welded pipes, (20” to 60” sch40, sch80, sch160),

API 5CT seamless casing, and tubing, (2 3/8” to 20” K55, J55, N80, L80, P110),

Pipe fittings, elbow, reducer, ,tee,cap, flange

Introduction of correlation between steel material properties and temperature

 There are two types of steel material coefficient related to temperature: one is steel material coefficient related to mechanical properties of steel materials; The other is the material coefficient of steel related to heat conduction. The former are E, G, v, a; Among the latter are C(specific heat capacity), ρ (density), k(heat conduction coefficient) and so on. These coefficients are not actually constant, but vary with temperature. However, when the temperature is not high, the average value is usually treated as a constant, but in the case of high temperature and large change, it must consider its change with the temperature.

Relationship between elastic coefficient and temperature of iron and steel materials

The elastic coefficient E and shear modulus G decrease with increasing temperature, and Poisson's ratio v changes little with temperature. E, G and temperature are measured by static method and dynamic method, the former is tested by loading in a high temperature furnace, the latter is measured by vibration method or ultrasonic pulse method. The vibration method is to make the specimen do elastic vibration in the high temperature furnace, and determine the elastic constant by measuring the frequency. The ultrasonic rule is to give the specimen ultrasonic waves, and measure E, G, v by measuring the propagation speed of the waves.

The relationship between heat coefficient and temperature

The thermal coefficient of metal materials is generally linear with the temperature, the linear expansion coefficient a generally increases with the increase of temperature, the thermal conductivity k decreases with the increase of temperature, and the specific heat capacity increases with the increase of temperature. Through the linear slope or curve of the relationship between the heat coefficient and temperature measured by the test, the change of the heat coefficient of the specific material with the temperature can be known.

Thermal fatigue of steel materials

When the ductile steel material increases with the temperature, even if the stress exceeds the yield point, it will not be immediately damaged, but even if the stress level is low, if there is a large temperature change repeatedly, it will eventually crack due to fatigue and lead to damage. This phenomenon is called thermal fatigue.

Assume that at the beginning of the test, the rod is fixed at the highest temperature and then cooled to produce tensile stress, with OAF being a stress variation line. Then, if the heat is reheated, the stress-strain line begins to move down parallel to OA, yielding at a stress lower than the cooling cycle tension, and finally reaching point E. If it is kept at the highest temperature for a period of time, the compressive stress decreases to the E' point due to stress relaxation. If it begins to cool again, it rises along E 'f ', reaching F' point at the lowest temperature. Since no pressure relaxation occurs at the lowest temperature. If the heating starts again, the line falls along F'E" to E" at the highest temperature. Here, due to stress relaxation, the stress decreases and moves to E"'. If cooling starts again, F" is reached at the lowest temperature along the curve E"'F".

If this cooling-heating cycle is repeated, the stress-strain diagram depicts a hysteresis curve each time, and the associated retroplastic strain is the cause of thermal fatigue. The maximum and minimum temperature, the average temperature, the holding time of the maximum temperature, the repetition rate, the elastoplastic property of the material are all factors that affect the thermal fatigue.

The strength of thermal fatigue refers to the relationship between the plastic strain εP of a cycle and the number of repetitions N to reach failure.

The above mentioned is only the unidirectional thermal stress fatigue of the material, and the thermal fatigue of the actual structure is multi-directional and is a special research field.

Email: sale@galaxy-steel.com

 

Wechat: LXF13931739696.  Whatsapp: 008613931739696

 

Website:  https://www.friend-steelpipes.com/  https://www.cz-steelpipe.com/

 

CANGZHOU GALAXY STEEL PIPE CO., LTD

 

China Reliable Steel Pipe and Pipe Fittings Manufacturer and Supplier

 

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3PE coating and epoxy lining SSAW welded linepipe API 5L X52 PSL2 42"...

Various structures and inclusions in steel (Chapter Three)

 Standard for determination of non-metallic inclusions in steel

1. Scope

Microscopic evaluation method for nonmetallic inclusions in rolled or forged steels with compression ratio greater than or equal to 3 by standard spectrogram.

2 Sampling

The morphology of inclusions depends to a large extent on the degree of compression deformation of the steel, so it is only possible to compare the measured results on the sections prepared by sample billet after similar degree of deformation.

The polished surface area of the specimen for measuring inclusion content shall be approximately 200mm²(20mm X10mm) and shall be parallel to the longitudinal axis of the steel, located halfway from the outer surface of the steel to the center.

If the product standard does not specify, the sampling method is as follows:

Steel rods or billets with a diameter or side length greater than 40mm: the inspection surface is the partial radial section from the outer surface of the steel to the center.

3. principle

The observed test site was compared with the standard spectrum, and each type of inclusion was rated.

These rated images are equivalent to a square field of view with an area of 0.50mm² on a longitudinally polished plane 100 times lower.

According to the morphology and distribution of inclusions, the standard rating chart is divided into five categories: A, B, C, D and DS.

These five categories of inclusions represent the most commonly observed types and forms of inclusions:

Class A (sulfides) : A single gray inclusion with high ductility and a wide range form ratio (length/width), generally with rounded ends.

Class B (alumina) : most undeformed, angular, small shape ratio (generally <3), black or bluish particles, arranged in a line along the rolling direction (at least 3 particles).

Class C (silicates) : A single black or dark gray inclusion with high ductility and a wide range form ratio (generally ≥3), with an acute Angle at the end.

Class D (spherical oxides) : non-deformed, angular or round, small shape ratio (generally <3), black or bluish, irregularly distributed particles.

Class DS (single particle spherical class) : round or nearly round, diameter ≥13μm of single particle inclusion.

Each type of inclusion is divided into two series of fine and coarse according to the different width of non-metallic inclusion particles.

4. Determination of inclusion content

The sample was magnified 100 times under the microscope, and the inclusion grade was evaluated in the field of view of a square with a side length of 71mm and an actual area of 0.5mm².

Method A is used for production inspection

The entire finish should be inspected. For each type of inclusion, the number of levels of the standard picture corresponding to the worst field of view on the examined surface is recorded by fine and coarse series.

For individual inclusions whose length exceeds the side length of the field of view (0.71mm), or whose width or diameter is greater than the maximum of the coarse system (see Table 2), they should be assessed as super-size inclusions and recorded separately. However, these inclusions should still be included in the rating of the field of view.

For strip inclusions that are not in a straight line, if the longitudinal distance between the two inclusions is less than or equal to 40μm and the transverse distance along the rolling direction is less than or equal to 10μm, it shall be regarded as an inclusion.

If the widths of inclusions within an inclusion are different, the maximum width of the inclusion shall be regarded as the width of the inclusion.

If the inclusion length is too long or the width is too large, it should be recorded separately and included in the field of view for rating (the length of the extra long is 0.71mm).

5. Inclusion grade calculation (measurement rating picture grade of inclusions above 3)

Class A sulfide (length L expressed by μm) : Lg(i)=[0.560 5lg(L)]-1.179

Class B alumina: Lg(i)=[0.462 6lg(L)]-0.871

Class C silicate: Lg(i)=[0.480 7lg(L)]-0.904

Class D spherical oxides, where n is the amount in each field of view: Lg(i)=[0.5lg(n)]-0.301

DS class single particle spherical oxide, d is diameter: i=[3.311g(d)]-3.22

CANGZHOU GALAXY STEEL PIPE CO., LTD

sale@galaxy-steel.com

 

Wechat: LXF13931739696.

Whatsapp: 008613931739696

 

Website: 

 https://www.friend-steelpipes.com/ 

 https://www.cz-steelpipe.com/

 My company hot sale steel pipe and pipe fittings:

 ASTM A106 B seamless pipes,（1” to 24” sch40, sch80),

API 5L GR.B steel pipes, (seamless pipe, LSAW pipe, SSAW pipes, 1” to 110” sch 40, sch80),

Boiler tubes,( 20G. 12Cr1MoVG, ASTM A335 P5, P9, P11),

ASTM A333 GR.6 seamless pipes, ( 1” to 24” sch40, sch80, sch160),

TP304/304L, TP316/TP316L, stainless steel pipes, (1” to 48” sch10, sch20, sch40, sch80),

API 5L X65, X70 PSL2 LSAW welded pipes, (20” to 60” sch40, sch80, sch160),

API 5CT seamless casing, and tubing, (2 3/8” to 20” K55, J55, N80, L80, P110),

Pipe fittings, elbow, reducer, ,tee,cap, flange