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Laser cladding technological method and alloy material for laser cladding

A technology of laser cladding and alloy materials, which is used in the repair of journals, end faces of high temperature and high pressure valves, laser cladding process methods and the fields of alloy materials, which can solve unsatisfactory mechanical properties, high laser power density and process control requirements. High and other problems, to achieve good anti-cavitation performance, simple and easy operation, good process adaptability

Active Publication Date: 2012-07-25
HANGZHOU BOHUA LASER TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, there is currently no special powder for laser cladding, especially for laser cladding of high-capacity steam turbine blades, which requires certain hardness, strength, elongation, bending resistance and good cavitation resistance.
The existing powder either has poor cavitation resistance, or the mechanical properties are not satisfactory, or pores, pinholes, or even cracks are generated during the cladding process. Cobalt-based alloy welding repair, "Electric Power Science and Engineering", Vol. 24, No. 7, 2008, 28-30) introduces the repair of blades, but it needs to be preheated to 250-350 °C, and the process control is very demanding. Heat treatment at 680°C is difficult to apply in practice
The reason is that due to the high power density of the laser, its cladding process is very different from conventional thermal spraying. In the cladding of actual parts or due to the burning of elements, pores, slag inclusions, and inclusions are formed, and the hardness is reduced. ; or due to the different expansion properties of the substrate and the cladding layer, serious cracks appear and cannot be practically applied

Method used

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  • Laser cladding technological method and alloy material for laser cladding
  • Laser cladding technological method and alloy material for laser cladding
  • Laser cladding technological method and alloy material for laser cladding

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Embodiment 1: An alloy material for laser cladding, the chemical composition (weight percentage) of alloy elements is C: 0.85%; Cr: 35%; Fe: 5%; Si: 0.5%; W: 5.0%; Mo: 1.2%; Ni: 7%; V: 1.5%; Ti: 1.0%; B: 0.5%; Nb: 0.3%; Re: 0.6%; Co: balance.

[0023] The preparation method is as follows:

[0024] 1. Calculate the addition amount of various master alloys such as ferrochrome, ferrovanadium, ferrosilicon, and ferroboron (considering the different burning loss rates of each element when calculating).

[0025] 2. After weighing, bake in an oven at 200°C.

[0026] 3. Add high melting point and magnetic elements first, and then add elements that are easy to burn.

[0027] 4. After melting, remove slag, refine and add rare earth elements.

[0028] 5. Open the water and gas circuit, control the pressure and liquid level.

[0029] 6. Place the preheated middle leakage bag on the nozzle, and pour the alloy liquid in the furnace into the middle leakage bag.

[0030] 7. After ...

Embodiment 2

[0033] An alloy material for laser cladding, the chemical composition (weight percentage) of alloy elements is C: 0.95%, Cr: 42%, Fe: 3%, Si: 1.2%, W: 5.5%, Mo: 1.5% , Ni: 6%, V: 1.8%, Ti: 2.0%, B: 1.2%, Nb: 0.5%, Re: 1.0%, Co: balance.

[0034] The preparation method is the same as in Example 1.

[0035] The hardness of the cladding layer prepared by laser cladding with this ratio of alloy powder is HRC52-57. In addition to being applied to steam turbine blades, it can also be applied to the repair of shaft journals and valve end faces, with the same performance and effect.

Embodiment 3

[0037] A laser cladding process method for substituting steam turbine blade inlaid alloy sheets, comprising the following steps:

[0038] 1. If figure 1 As shown, the back arc of blade 1 (including the original R side) is milled off by 1 mm to form milling groove 2; the back arc side is milled off to 1 / 5 of the thickness, but the total depth does not exceed 1 mm; the forming knife can be used to complete it in one step by CNC milling machine .

[0039] 2. According to the size of the milled part, the robot motion track is compiled, and the overlap rate of cladding programming is 55%.

[0040] 3. Adopt optical fiber or semiconductor laser, select the powder of embodiment 1 and embodiment 2, and its particle size is -140+325 mesh (particles are lower than 140 mesh, higher than 325 mesh, and the particle size is within this range), dispatch The powder amount is 14g / min, and the powder is fed by inert gas; the spot diameter is 5mm, the power is adjusted to 1800W, the laser scann...

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Abstract

The invention discloses an alloy material for laser cladding. The alloy material is alloy powder and contains the following components in percent by weight: C: 0.85-0.98%, Cr: 35-45%, Fe: 3-5%, Si: 0.5-1.0%, W: 3.5-5.5%, Mo: 1 .0-1.5%, Ni: 6-8%, V: 1.5-2.0%, Ti: 1.0-2.0%, B: 0.5-1.5%, Nb: 0.10-0.50%, Re: 0.5-1.5%, and Co: the balance. The invention also discloses a laser cladding technological method adopting the alloy material. In the technical scheme, under the combined action of the added alloy elements, cladding layer tissue is uniform and tiny and has no pore, no inclusion and no included slag; and preheating is not needed when a blade is cladded and crack does not emerge. The alloy material has high rigidity and excellent cavitation resistance; without follow-up heating treatment, acladded part can be directly fine machined to use; and the laser treatment technology has good adaptivity and is simple and feasible in operation.

Description

technical field [0001] The invention belongs to the field of material science and laser processing, and in particular relates to a laser cladding process method and its alloy material, which is especially suitable for direct laser cladding of cavitation-resistant layers of long blades of large-capacity steam turbines and blades that fail due to cavitation It can also be used for the repair of journals and end faces of high-temperature and high-pressure valves. Background technique [0002] The experience in the operation of steam turbine generator sets in the past 20 to 30 years shows that the best way to improve the cavitation resistance of steam turbine blades is to inlay Stellite alloy sheets. Due to the requirements of modern energy industry for high efficiency and energy saving, the capacity of generating sets has been developed to 300, 600, and 1000 megawatts. The blades of this type of unit are long and the linear speed is high, so the requirements for the strength a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C19/07C23C24/10B23K26/34
Inventor 姚建华楼程华
Owner HANGZHOU BOHUA LASER TECH
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