CN102220554B

CN102220554B - Method for surface modification treatment of X70 pipe line steel

Info

Publication number: CN102220554B
Application number: CN 201110142602
Authority: CN
Inventors: 孔德军; 吴永忠; 王文昌; 龙丹; 周朝政; 蔡金龙
Original assignee: Changzhou University
Current assignee: Liyang Chang Technology Transfer Center Co., Ltd.
Priority date: 2011-05-30
Filing date: 2011-05-30
Publication date: 2013-03-13
Anticipated expiration: 2031-05-30
Also published as: CN102220554A

Abstract

The invention discloses a method for surface modification treatment of X70 pipe line steel, belonging to the field of surface modification treatment of materials. In the invention, an Fe-Al alloy layer is prepared by a laser thermal radiation aluminizing treatment method; the surface of the coating is level and smooth; the surface tissue and the performance of the pipe line steel are changed; a matrix is combined with a boundary surface in a metallurgical way; and thus, an alloy coating with stronger salt spray corrosion resistance can be obtained. The method has important engineering application significance to improving the salt spray corrosion resistance of the pipe line steel.

Description

A kind of method of X70 pipe line steel surface modification treatment

Technical field

The present invention utilizes the laser radiation calorized coating to process X70 pipe line steel surface, produces the phase-change alloy layer on its surface, improves the pipe line steel solidity to corrosion, belongs to the material surface modifying process field.

Background technology

Along with the development of petroleum industry, transport pipe is owing to the loss that salt air corrosion causes also increasingly sharpens; Pipe line steel is the long mode of transport most economical apart from transfer oil, the security requirements such as intensity for the pipe line steel that develops to high strength, heavy caliber are more outstanding, corrosion is to affect the reliability of pipeline and the key factor in work-ing life, pipeline in the Deposits in Eastern Coastal China area is on active service under saline-alkali environment throughout the year, spot corrosion and stress corrosion crack all are huge disaster hidden danger, therefore, must carry out surface anticorrosive to pipe line steel processes.

Current pipeline steel surface preparation Fe-Al intermetallic compound coating main method has: thermospray, hot dipping are oozed, plasma etc.; The major defect of hot dipping cementation process is that coating is thin, hole is more, has plating leakage, meticulously adjusting under the condition of Infiltration Technics, can realize a small amount of microcell metallurgical binding, but the overwhelming majority of coating and matrix is combined into mechanical bond; Adopt the synthetic Fe-Al intermetallic compound coating of high speed arc spraying and plasma spraying technology reaction, but be subjected to the restriction of sprayed coating and mother metal bonding strength, coating is peeled off in the process under arms easily; Adopt the powder embedding to prepare Fe-Al intermetallic compound coating, the alloy layer that obtained densification, pore-free, be mingled with, there is certain fluctuating on the cladding surface, realized good metallurgical binding between alloy layer and matrix, but its Fe-Al intermetallic compound powder preparation process is complicated, be difficult to accomplish scale production, dust polluting environment, work under bad environment; Patent of the present invention prepares the Fe-Al alloy layer by LASER HEAT radiation aluminising treatment process, the surfacing of coating is smooth, pipe line steel textura epidermoidea and performance change, matrix and interface combination are metallurgical binding, obtain the stronger alloy coat of salt spray resistance corruption, have important engineering application value for the anti salt spray corrosion that improves pipe line steel.

Summary of the invention

The X70 pipe line steel is in some Service Environment such as Gobi desert, desert etc., for toughness, the erosion resistance of pipeline very high requirement arranged.

Patent of the present invention adopts the LASER HEAT radiation that its surface is heat-treated, and the Fe atom by convection current diffusion and thermodiffusion a series of physicochemical change has occured in Al atom and the matrix, forms the Fe-Al alloy layer at matrix surface.

A kind of method in the alitizing of X70 pipe line steel, supplying the aluminium agent is industrial pure Al, it is characterized in that: in aluminium powder, add water glass as caking agent, aluminium powder is modulated into pasty state, the add-on of water glass so that be modulated into the aluminium powder of pasty state can carry out on the pipe line steel surface craft evenly brushing get final product, utilize laser as thermal source, the high-energy that is coated with the brush layer absorbing laser is fused into liquid and matrix Fe element interpenetrates, form metallurgical binding, the whole surface laser thermal radiation aluminising of mobile realization by pipe line steel is processed, when high energy beam laser is strafed, Fe and Al atom mutually mutual diffusion and phase interfacial reaction occur in X70 pipe line steel near surface, should be after 900 ℃ of High temperature diffusion be processed 2h, so that Al after the LASER HEAT radiation, the Fe element further spreads, and forms fully infiltration.

Alloy layer is divided into two-layer: outer aluminum layer, middle laser molten pool alloy flow layer ( ηPhase (Fe ₂Al ₅) and a small amount of FeAl), the parting line power spectrum can find out that the Al element in the coating is evenly distributed, the phase diffusion zone is consistent with Al content in the coating, Al content falls sharply and is the base material contents level in the matrix, the distribution of Fe is opposite with the Al element, explanation is in fluidised bed, and Fe and Al fully permeate, and has well kept the original structure property of matrix; Alloy layer and matrix engrail interpenetrate, and are metallurgical binding, and bonding strength is high, and wear resistance is good, is not simple mechanical bond.

The mass percent of Al is 70% in the described aluminium powder that is modulated into pasty state, and the mass percent of water glass is 30%.

According to above-mentioned technique basis, in aluminium powder, except adding water glass as the caking agent, add again pure aluminium silicate, and according to mass percent: Al 50%; Pure aluminium silicate 20%; Water glass 30% configuration; find to need not anneal after the LASER HEAT radiation aluminising; the surface quality of its coating with only add water glass and carry out laser radiation and the same good through the surface quality of anneal coating; such as Fig. 5, shown in Figure 6; for manufacture craft has been saved time and cost, for large-scale production provides possibility.

Description of drawings

Fig. 1 X70 pipe line steel original surface scanning electron microscope (SEM) photograph;

Fig. 2 X70 pipe line steel hot-dip aluminizing using is processed the rear surface scanning electron microscope (SEM) photograph;

Fig. 3 X70 pipe line steel LASER HEAT radiotreatment annealing surface scanning electron microscope (SEM) photograph;

Fig. 4 X70 pipe line steel LASER HEAT radiotreatment annealed interface scanning electron microscope (SEM) photograph;

The radiation of Fig. 5 X70 pipe line steel LASER HEAT adds pure aluminium silicate without the annealing surface scanning electron microscope (SEM) photograph;

The radiation of Fig. 6 X70 pipe line steel LASER HEAT adds pure aluminium silicate without the annealed interface scanning electron microscope (SEM) photograph;

Fig. 7 X70 pipe line steel laser treatment rear interface energy spectrum analysis figure, (a) Fe element line power spectrum, b) Al element line power spectrum;

X ray collection of illustrative plates after the alitizing of Fig. 8 X70 pipe line steel is processed, (a) virgin state is after b) LASER HEAT radiation aluminising is processed;

Scanning electron microscope (SEM) photograph after the original surface corrosion of Fig. 9 X70 pipe line steel surface;

The scanning electron microscope (SEM) photograph of Figure 10 X70 pipe line steel hot-dip aluminizing using sample corrosion rear surface;

Scanning electron microscope (SEM) photograph after the corrosion of Figure 11 X70 pipe line steel LASER HEAT radiotreatment.

Embodiment

Adopt NEL2.5KW fast Axial-flow Co ₂Laser apparatus, LASER HEAT radiotreatment processing step is: surface degreasing → rust cleaning → oven dry → LASER HEAT radiation → diffusion annealing or surface degreasing → rust cleaning → oven dry → LASER HEAT radiation; Processing parameter is: power 0.5-2.5KW, and sweep velocity 0.5-2mm/s, spot diameter 0.5-1.5mm, outward current are 200-220A, brushing thickness is 0.3mm-0.8mm, radiated time 5～10min.

Embodiment 1

(1) adopts NEL2.5KW fast Axial-flow CO ₂Laser apparatus, LASER HEAT radiotreatment processing step is: surface degreasing → rust cleaning → oven dry → LASER HEAT radiation → diffusion annealing, processing parameter is: power 1KW, sweep velocity 1mm/s, spot diameter 1mm, outward current are 210A, brushing thickness is 0.3m, radiated time 10min; Hot-dip aluminizing using X70 pipe line steel surface has pit to occur as shown in Figure 2, has plating leakage, is the typical defect that hot dipping is oozed; When laser was strafed on the pipe line steel surface, coatingsurface was comparatively smooth, fine and close, continuous, and coat-thickness is 0.5mm, did not have obvious crackle tendency, had kept metalluster, shown in Fig. 3,4, had improved the matrix wear resisting property.

(2) variation of employing EDS, its chemical element distribution of XRD analysis and chemical substance, the content of Al element maintains a constant basis (58.69%), significantly decline also do not occur in zone of transition, and this illustrates that element distributions in coating is more even; Original sample is organized as

, generated FeAl, Fe after the LASER HEAT radiotreatment ₂Al ₅And Al ₂O ₃Improved the corrosion resistance of pipe line steel.

(3) hot dipping is oozed, it has been carried out 8 hours salt spray corrosion test after the laser treatment; Erosion profile is shown in Fig. 9/10/11, the corrosion of original sample is comparatively serious, large corrosion pit has appearred, the pull-up phenomenon occurs, hot dipping oozes that to process the sample corrosion also comparatively serious, outlet etching crack, the erosion resistance of alloy layer will be higher than matrix after the laser hot-dip aluminizing using was processed, well solved the spot corrosion problem of pipe line steel, because the sample top layer after the laser treatment has produced the pure Al layer of one deck, oxidation generates Al in air ₂O ₃, because the current potential of aluminium is lower than iron, when galvanic corrosion, aluminium at first is corroded, corrosive medium Cl ^-Ion is difficult to be contacted with matrix Fe element, so that body material has obtained protection.

Embodiment 2

Adopt NEL2.5KW fast Axial-flow CO ₂Laser apparatus, LASER HEAT radiotreatment processing step is: surface degreasing → rust cleaning → oven dry → LASER HEAT radiation; In aluminium powder, except adding water glass as the caking agent, add again pure aluminium silicate, and according to mass percent: Al 50%; Pure aluminium silicate 20%; Water glass 30% configuration, processing parameter is: power 2.5KW, sweep velocity 2mm/s, spot diameter 1.5mm, outward current are 220A, brushing thickness is 0.8mm, radiated time 5min finds to need not anneal after the LASER HEAT radiation aluminising, the surface quality of its coating with only add water glass and carry out laser radiation and the same good through the surface quality of anneal coating, such as Fig. 5, shown in Figure 6, the scanning electron microscope (SEM) photograph after energy spectrum analysis, X ray collection of illustrative plates and the corrosion is with embodiment 1.

Claims

1. the method for an X70 pipe line steel surface modification treatment, supplying the aluminium agent is industrial pure Al, can form the Fe-Al intermetallic compound on X70 pipe line steel surface, it is characterized in that: in aluminium powder, add water glass as caking agent, aluminium powder is modulated into pasty state, the add-on of water glass so that be modulated into the aluminium powder of pasty state can carry out on the pipe line steel surface craft evenly brushing get final product, utilize laser as thermal source, the high-energy that is coated with the brush layer absorbing laser is fused into liquid and matrix Fe element interpenetrates, form metallurgical binding, the whole surface laser thermal radiation aluminising of mobile realization by pipe line steel is processed, should process through High temperature diffusion after the LASER HEAT radiation, so that Al, the Fe element further spreads, and forms fully infiltration; Described laser technical parameters is: power 0.5-2.5kW, and sweep velocity 0.5-2mm/s, spot diameter 0.5-1.5mm, outward current are 200-220A, radiated time 5～10min; Described High temperature diffusion is processed and is referred to process 2h 900 ℃ of High temperature diffusion.

2. the method for a kind of X70 pipe line steel surface modification treatment as claimed in claim 1 is characterized in that: the aluminium powder that is modulated into pasty state carries out the manual evenly thickness of brushing on X70 pipe line steel surface be 0.3mm-0.8mm.

3. the method for an X70 pipe line steel surface modification treatment, be industrial pure Al for the aluminium agent, can form the Fe-Al intermetallic compound on X70 pipe line steel surface, it is characterized in that: in aluminium powder except adding water glass as the caking agent, add again pure aluminium silicate, and according to mass percent: Al 50%; Pure aluminium silicate 20%; Water glass 30% configuration, aluminium powder is modulated into pasty state, carry out evenly brushing of craft on the pipe line steel surface, utilize laser as thermal source, the high-energy that is coated with the brush layer absorbing laser is fused into liquid and matrix Fe element interpenetrates, form metallurgical binding, process by the whole surface laser thermal radiation aluminising of mobile realization of pipe line steel; Described laser technical parameters is: power 0.5-2.5kW, and sweep velocity 0.5-2mm/s, spot diameter 0.5-1.5mm, outward current are 200-220A, radiated time 5～10min.

4. the method for a kind of X70 pipe line steel surface modification treatment as claimed in claim 3 is characterized in that: the aluminium powder that is modulated into pasty state carries out the manual evenly thickness of brushing on X70 pipe line steel surface be 0.3mm-0.8mm.