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Characteristics of bi metal clad wear resistant pipe

New rare-earth wear-resistant alloy tube is a new technology using EPC EPC vacuum suction casting, the process can avoid all the casting defects (porosity, slag inclusion, loose, deformation major) material ingredients in the original alloy material: FeCr, FeMn, FeMo, Ni, Re, FeSi, add vanadium iron (FeV), niobium iron (FeNb), copper (Cu), make it has both the wear resistance of high alloy casting materials, and has high mechanical strength and impact performance, at the same time improve the weldability of the material.

1. High abrasion resistance:
the rare earth wear-resistant alloy pipe has been equipped with strong abrasion resistance performance. After the addition of FeV, FeNb and Cu, the metallographic structure of the material has changed again. The grain is more compact, the strength is higher and the plasticity is stronger.

2. Good comprehensive performance:
new rare-earth wear-resistant alloy tube is a new technology using EPC EPC vacuum suction casting, the process can avoid all the casting defects (porosity, slag inclusion, loose, deformation major) material ingredients in the original alloy material: FeCr, FeMn, FeMo, Ni, Re, FeSi, add vanadium iron (FeV), niobium iron (FeNb), copper (Cu), make it has both the wear resistance of high alloy casting materials, and has high mechanical strength and impact performance, at the same time improve the weldability of the material.

3. High temperature resistance:
strong corrosion resistance.The content of Ni and Cr elements in the alloy directly determines the temperature resistance of the material.The content of Cr element and Cu element determines the corrosion resistance of the material. The reasonable combination of these elements enables this new type of rare earth wear-resistant alloy to have several properties at the same time, and can be used under various harsh working conditions.

4. Advanced technology:
stable performance.EPC die - loss vacuum suction casting new technology, mold size precision high, materials uniform structure, performance stability, especially for straight pipe, reducing pipe, unequal thickness pipe, eccentric pipe, cone pipe can achieve integral casting.

5.Low resistance of pipeline system:
the change of metallographic structure makes the matrix grain of casting more compact.The advanced process eradicates the phenomenon of porosity of pores, slag inclusion and structure. The inner wall of the pipeline is smooth like mirror after being transported through a period of time, which greatly reduces the running resistance of the pipeline, improves the service cycle of the pipeline and further improves the wear-resisting property of the material.

6. Convenient installation:
flange, quick joint and direct welding can be used for installation.Due to the addition of FeV, FeNb and Cu, new materials are improved through heat treatment, but at the same time it ensures the random cutting, missing, welding and other installation means of materials.

Application:
Performance indicators:
Bimetal wear - resistant elbow technology requirements

process requirement

1. Wear-resistant elbow is made of bimetal wear-resistant composite.
2. The general manufacturing method is made by the combination of the vacuum absorption casting process of the vanishing mold, and the manufacturing process of the commodity shall be indicated in other processes.
3. Adopt composite alloy steel wear-resistant layer, each elbow shall be eccentric compound, and the outside of the elbow shall be thickened according to the working condition to achieve the life design of the outside and inside.In order to reduce the resistance of coal powder transportation, the elbow should be smooth and excessive, and the shrimp waist welding method should not be adopted, so as to ensure that the inner diameter of the throughflow at all parts is 510mm, and no convex platform can be found.
4. Wear-resistant lining is made of high chromium alloy (not lower than KMTBCr28), with service life over 2 years and annual wear less than 5mm.The outer wear resistant lining thickness is 28mm, the inner wear resistant lining thickness is 22mm, and the hardness of HRC is greater than 55.Outer pipe of lining part 558*10, connecting pipe 508*10, outer ring 558*22, material is 10 steel.Seamless pipes (or welded pipes) can be used, and their performance should meet the requirements of GB2087, GB8163.

Inner wall material casting and equipment rendering
Inner wall material casting and equipment rendering

The bimetal wear-resistant tube inner wall KMTBCr28 has stable quality and good comprehensive performance. Adding a certain amount of rare earth elements can improve the alloy quality of steel, refine the grain and form a protective film on the surface.A certain amount of Mo was added to make the alloy have certain antioxidant effect and increase service life at high temperature.A certain amount of boron carbide can be added to control the hardness in the range of HRC45 ~ 65, and solve the contradiction between the hardness and weldability of wear-resistant steel.

Quality requirements

The inner and outer surface of bimetal wear-resistant elbow should be smooth and clean, without burrs, burrs, cracks, loose, pores or bubbles;The inner wall of the wear-resisting elbow should be smooth without accumulated powder.The bend should have good thermal shock resistance. When there is a sharp change in temperature or welding connection, the inner layer of the wear-resistant pipe will not break and spalling due to the expansion or contraction of the inner layer.The dimensional deviation shall meet the requirements of product drawings and order agreement, and shall meet the provisions of GB3092, GB8162 and GB8163 without special requirements.The thickness deviation of lining is + / - 1.2mm.

Bimetal wear - resistant pipe chemical composition:

Grade C Si Cr Mo Mn Ni S
KMTBCr28 3.00 1.19 27.00 0.25 1.20 0.45 0.06

performance index:

项目 硬度HRC 冲击值(AKJ/cm²) 磨耗量(g/24h) 承压等级(Mpa) 抗拉强度(N/mm²)
指标 ≥80 ≤3 0.0008~0.002 ≤4.0 420

Mechanical property :

Flexure
Strength
Tensile
Strength
Elongation Cross Section
Stretch Ratio
Impact
Toughness
Hardness
of Wearable
Layer
Hydrostatic
Testing
Pressure
MN/㎡ MN/㎡ % % J/c㎡ HRC Mpa

>610 >700 5 5.1 >15 >38 5.6-12.9

Specification requirements:

1. The inlet and outlet of the wear-resistant elbow shall be the straight pipe section with the same wear-resistant material of the elbow. Except special instructions, the length of the straight pipe section imported is 200mm and the length of the straight pipe section exported is 400mm.

2. The connection between wear-resistant elbow and pipe is made by welding.Elbow on interfaces with the transition of materials, the interface transition pipe to Ф 508 x 10 mm in diameter, material of 10 # steel (described in clause 4.1 of the connecting pipe 508 * 10), in order to meet the needs of the field of welding.There should be no special requirement for product field welding to ensure good performance of product welding at ambient temperature.

3. The length of inlet and outlet straight pipe segments of wear-resistant elbow is L1 and L2, which refers to the total length of straight pipe segments, including the length of solderable segment.

Service life requirement:

Service life: ensure that the elbow does not leak during 2 years of operation.Under the premise of guaranteeing the weight of the wear-resistant elbow, the service life of the wear-resistant elbow under the working state shall not be less than 16600 hours.During the service life, make sure the wear-resistant elbow is free of wear and powder leakage.In wear-resisting bend life period abnormal operating conditions, the product should guarantee the high temperature of 350 ℃, lining of wear-resisting layer fracture, peeling off.

Requirement of the surface:

The outer wall shall be painted uniformly and uniformly, and the outer side of the elbow shall be marked with obvious elbow number, Angle, curvature radius and medium flow direction.

Technical parameters:

Pulverized coal pipe diameter  wall thickness: Ф 508 x 10 mm (made of steel no. 10)

Working medium: air powder mixture

Pressure capacity: 0.35MPa

Medium design temperature: 17000Pa

Design of medium pressure: 80 ℃ (maximum 100 ℃)

Medium velocity: 18 ~ 32m/s

Coal fineness: R90 = 20 ~ 22%

Wind coal ratio: 1.3-1.8kg /kg

 

The production process of bimetal wear - resistant pipe with epc casting process

Epc is also called the real mold casting, will be the same as the casting dimension of foam model after brush refractory materials and drying, buried in the sand dry quartz sand or orb, magnesia olivine sand vibration model, and then under the negative pressure casting, the foam model gasification, liquid metal model position, after cooling solidification form a new type of foundry casting method.Epc technology is praised as "the green revolution of foundry industry".

Epc process:

消失模铸造工艺流程
消失模铸造工艺流程

Process features:

Flexible design: provides sufficient freedom for structural design of casting.A highly complex casting can be made by a combination of foam plastic molds.

Reduce investment and production cost: reduce casting blank weight and machining allowance.

No sand core in the traditional casting: therefore, the thickness of the casting in the traditional sand mold casting will not be uneven due to the incorrect size of the sand core or the inaccurate location of the lower core.

High casting precision: epc casting is a new process of near zero tolerance and accurate molding, which requires no mold taking, no dividing surface, and no sand core. As a result, the casting has no flying edge, burr and drawing slope, and reduces the size error caused by mold core combination.

Clean production: no chemical binders in sand moulds, foam plastics is environmentally friendly at low temperature, and the recovery rate of old sand is over 95%.

Process summary:

Epc equipment process, like other foundry processes, has its shortcomings and limitations. Not all castings are suitable for epc production.



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