阅读说明：本技术 一种激光熔覆制造冷轧去毛刺辊功能层合金粉末及制备方法 (Laser cladding manufactured cold-rolled deburring roller functional layer alloy powder and preparation method thereof ) 是由 霍凤萍 陈海涛 董思远 于 2021-08-18 设计创作，主要内容包括：本发明属于表面处理技术领域,涉及用激光熔覆工艺制备耐磨损高硬度涂层,具体一种激光熔覆制造冷轧去毛刺辊功能层合金粉末及其工艺方法。所述激光熔覆制造冷轧去毛刺辊功能层合金粉末,由包括以下质量百分比组分组成：VN粉末1%-5%,Al粉末0.1%-1%,余量为铁基合金粉末。本发明提供的修复方法熔覆层厚度大,抗压入性能好,具有较高的红硬性保持能力,最重要的是绿色环保,不会对环境造成损害,而且可通过磨削多次利用,提高辊子使用效率,降低了辊耗,提高机组连续作业率,给企业降低了修复成本。(The invention belongs to the technical field of surface treatment, relates to a wear-resistant high-hardness coating prepared by a laser cladding process, and particularly relates to cold-rolled deburring roller functional layer alloy powder prepared by laser cladding and a process method thereof. The laser cladding manufactured cold-rolled deburring roller functional layer alloy powder comprises the following components in percentage by mass: 1-5% of VN powder, 0.1-1% of Al powder and the balance of iron-based alloy powder. The repairing method provided by the invention has the advantages of large cladding layer thickness, good anti-pressing performance, higher red hardness maintaining capability, environment friendliness, no damage to the environment, repeated grinding utilization, improvement on the use efficiency of the roller, reduction in roller consumption, improvement on the continuous operation rate of a unit and reduction in repairing cost for enterprises.)

1. A cladding material of a cold-rolled deburring roller for laser cladding is iron-based alloy powder added with VN + Al and comprises the following components in percentage by mass: 1-5% of VN powder, 0.1-1% of Al powder and the balance of iron-based alloy powder.

2. The cladding material of the cold-rolled deburring roller for laser cladding of claim 1, wherein the iron-based alloy powder comprises the following components in percentage by mass: 1.5 to 2 percent of C, 4 to 5 percent of Cr, 4 to 6 percent of V, 4.5 to 6 percent of Co, 10 to 13 percent of W and the balance of iron.

3. The cladding material of a cold-rolled deburring roller for laser cladding as claimed in claim 1, wherein said VN powder has a particle size of-500 to +800 mesh and a purity of 99% or more.

4. The cladding material of the cold-rolled deburring roller for laser cladding as claimed in claim 1, wherein the Al powder has a particle size of-200 to +300 mesh and a purity of 99% or more.

5. The cladding material of the cold-rolled deburring roller for laser cladding as claimed in claim 1, wherein the particle size of the iron-based alloy powder is-125 to +300 mesh.

6. A method for repairing a laser cladding cold-rolled deburring roller comprises the following specific steps:

step 1, before construction, a failure roller is ground to remove a plated hard chromium layer, the grinding depth is 20-30 microns, and the chromium plated layer is removed through hardness detection;

step 2, machining and turning a 0.5mm fatigue layer, and detecting flaws without cracks;

step 3, preparing functional layer alloy powder, mixing the powder through a powder mixer, and carrying out cladding work on the surface of the deburring roller by the uniformly mixed powder according to laser cladding process parameters;

step 4, after cladding, carrying out surface flaw detection and heat treatment after qualification, wherein the heat treatment process is 560 ℃, preserving heat for 3 hours,

the cooling mode is air cooling;

step 5, grinding to meet the size requirement, wherein the hardness can reach 62HRC +/-1;

and 6, carrying out a sand blowing process to meet the roughness requirement of the final finished product.

7. The cladding material of the cold-rolled deburring roller for laser cladding as claimed in claim 6, wherein the functional layer alloy powder in step 3 comprises the following components by mass percent: 1-5% of VN powder, 0.1-1% of Al powder and the balance of iron-based alloy powder, wherein the iron-based alloy powder comprises the following components in percentage by mass: 1.5-2% of C, 4-5% of Cr, 4-6% of V, 4.5-6% of Co, 10-13% of W and the balance of iron.

8. The cladding material of the cold-rolled deburring roller for laser cladding of claim 6, wherein the laser cladding process parameters in the step 3 are as follows: the preheating temperature of the cold-rolled deburring roller is 150-200 ℃, the powder feeding amount is 15-25 g/min, the laser power is 3-4 kw, the spot diameter is 3.6mm, the scanning speed is 800-1200 mm/min, the stepping is 1.7mm, the lap joint rate is 40-60%, and the single-layer cladding thickness is 0.8-1.5 mm.

9. The cladding material of the cold-rolled deburring roller for laser cladding as claimed in claim 6, wherein the cladding process in step 3 adopts a specially designed tool and a local atmosphere protection box with a slide rail, so that the cladding process is stably carried out, and the purity of the structure is ensured by measuring to 50ppm by an oxygen analyzer.

Technical Field

The invention belongs to the technical field of surface treatment, relates to a wear-resistant high-hardness coating prepared by a laser cladding process, and particularly relates to a cold-rolled deburring roller functional layer alloy powder prepared by laser cladding and a preparation method thereof.

Background

The plates in the cold rolling continuous annealing unit and the leveling unit are required to be leveled or polished to meet the requirement of high surface quality, edges of the two sides of the plates are required to be cut off by a circle shear, so that the edges are warped and small burrs exist due to shearing, and the plates are required to be leveled by a subsequent upper and lower deburring roller, so that the edges of the plates are leveled, and the plate surface quality is improved. The cold-rolled deburring roller is positioned behind the disc shear, the strip steel runs at a high speed between the upper deburring roller and the lower deburring roller, the strip steel speed is 600m/min, continuous high-speed friction contact is realized, small burrs on two sides of the strip steel are removed through the pressing force between the upper roller and the lower roller, the cold-rolled strip steel has high requirements on the surface quality, and the defects of pockmarks, pressed oxide skins and the like which are usually generated in hot-rolled products can not exist, so that the requirements on the quality of a roller way which is just in contact with the strip steel are also high, the defects of cracks and air holes on the surface of the roller way are required to be avoided, the requirement on the tissue uniformity is high, the hardness uniformity is high, the requirements on the performance are high in wear resistance and the hardness retention capacity under the high-speed friction, and the good thermal fatigue performance is required.

At present, an upper roller of a deburring roller is manufactured by adopting a Q345 base material thick-wall pipe, the surface is roughened and chromed, the thickness of a hard chromium layer is about 20 microns, the hardness is about 63-65 HRC, the service life is about 1 month, serious pit defects occur at a working part, the quality of a plate is influenced, and the continuous operation rate of a cold rolling unit is seriously influenced. When the chromium plating process is repeatedly used, the plating needs to be applied again after deplating, and meanwhile, with the increase of the national environmental protection, the chromium plating enterprises are further strictly supervised, and a new process method capable of replacing hard chromium plating is urgently needed.

The laser cladding technology is an efficient and convenient surface modification technology and has the following advantages: (1) the dilution rate of the cladding layer is low, and accurate control can be realized; (2) the heat influence on the base material is small, and local cladding or integral cladding can be carried out; (3) the thickness of the cladding layer is controllable; (4) the range of applicable materials is wide; (5) the process is flexible, and automation and industrialization are easy to realize. Based on the advantages, the method for manufacturing a large-area roller bed by utilizing the laser cladding technology becomes an important way and is widely researched.

Disclosure of Invention

In view of the problems in the prior art, the invention aims to provide a cladding material for manufacturing a functional layer of a cold-rolled deburring roller and a preparation method thereof. After the material is adopted to clad the cold-rolled deburring roller, the wear resistance of the roller surface under high-speed friction heat and the high-hardness retention capability can be improved, and the service life of a roller way is prolonged; the method for repairing the failed cold-rolled deburring roller by using the laser cladding technology not only can meet the requirements of high wear resistance and high hardness, the thickness can reach about 1mm, effective strength support can be formed, meanwhile, the performance is good in wear resistance, high in hardness uniformity and red hard, and more importantly, the thickness of the coating is enough to meet the requirement of recycling the roller way after multiple grinding, the use efficiency is improved, the working hours are saved, and the cost is saved.

In order to achieve the purpose, the invention adopts the following technical scheme.

A cladding material of a cold-rolled deburring roller for laser cladding is iron-based alloy powder added with VN + Al and comprises the following components in percentage by mass: 1-5% of VN powder, 0.1-1% of Al powder and the balance of iron-based alloy powder.

Further, the iron-based alloy powder comprises the following components in percentage by mass: 1.5 to 2 percent of C, 4 to 5 percent of Cr, 4 to 6 percent of V, 4.5 to 6 percent of Co, 10 to 13 percent of W and the balance of iron.

Preferably, the VN powder has a particle size of-500 to +800 meshes and a purity of more than 99%.

Preferably, the granularity of the Al powder is-200 to +300 meshes, and the purity is more than 99 percent.

Preferably, the particle size of the iron-based alloy powder is-125 to +300 meshes.

A method for repairing a laser cladding cold-rolled deburring roller comprises the following specific steps:

step 1, before construction, the failure roller is ground to remove the plated hard chromium layer, the grinding depth is 20-30 microns, and the chromium plated layer is removed through hardness detection.

And 2, machining and turning a 0.5mm fatigue layer, and detecting flaws without cracks.

Step 3, preparing functional layer alloy powder, mixing the powder through a powder mixer, and carrying out cladding work on the surface of the deburring roller by the uniformly mixed powder according to laser cladding process parameters, wherein the functional layer alloy powder consists of the following components in percentage by mass: 1-5% of VN powder, 0.1-1% of Al powder and the balance of iron-based alloy powder, wherein the iron-based alloy powder comprises the following components in percentage by mass: 1.5-2% of C, 4-5% of Cr, 4-6% of V, 4.5-6% of Co, 10-13% of W and the balance of iron.

And 4, performing heat treatment after the surface flaw detection is qualified after cladding, wherein the heat treatment process is 560 ℃, the heat preservation is performed for 3 hours, and the cooling mode is air cooling.

And 5, grinding to meet the size requirement, wherein the hardness can reach 62HRC +/-1.

And 6, carrying out a sand blowing process to meet the roughness requirement of the final finished product.

Further, the laser cladding process parameters in step 3 are as follows: the preheating temperature of the cold-rolled deburring roller is 150-200 ℃, the powder feeding amount is 15-25 g/min, the laser power is 3-4 kw, the spot diameter is 3.6mm, the scanning speed is 800-1200 mm/min, the stepping is 1.7mm, the lap joint rate is 40-60%, and the single-layer cladding thickness is 0.8-1.5 mm.

Furthermore, a specially designed tool and a local atmosphere protection box with a slide rail are adopted in the cladding process in the step 3, so that the cladding process is stably carried out, the content of the cladding material is measured by an oxygen analyzer to reach 50ppm, and the purity of the structure is ensured.

Compared with the prior art (hard chromium plating technology), the invention has the following beneficial effects.

(1) VN is added into the cladding material of the cold-rolled deburring roller for laser cladding and is uniformly distributed in a matrix, the particle size and the form of the VN are strictly controlled, the particle size is too coarse, hard particles can be fatigue-peeled off when being implanted, the particle size is too fine, the implantation effect is good, but the powder feeding fluidity is influenced, the VN can be uniformly distributed in the matrix in the alloy fusion process through screening the particle size range and the spherical state, fine and small wear-resistant particles are implanted in the high-hardness matrix, and the particle size is dissolved and a hard phase is precipitated and can be well combined with the matrix to form a whole, so that the hardness of the matrix is enhanced, and the wear resistance is greatly improved. Meanwhile, the precipitation of carbon and vanadium in the alloy can be promoted, and the strengthening effect can be more effectively exerted. VN can promote more nucleation during crystallization, the grain size is smaller, and therefore the fatigue performance is good, experiments prove that by adding VN, the adding amount of vanadium can be saved by 30-40% on the premise of achieving the same performance, and further the cost is reduced.

(2) The Al element in the cladding material of the cold-rolled deburring roller for laser cladding is taken as an independent addition component, and reacts with O impurities in a matrix during the fusion process, so that the structure can be purified, and the refining of crystal grains and the improvement of the purity of crystal boundaries are facilitated, so that the hardness and the toughness of a cladding layer are further improved; meanwhile, the addition of 0.1-0.8% of Al can promote the full reaction of a molten pool and is beneficial to gas floating, tests prove that the same scanning speed is achieved, no pore defect is found in the structure added with the Al, and tests simultaneously prove that when the addition amount exceeds the invention, a eutectic structure with low melting point can be generated, the toughness of a cladding layer is seriously influenced, and the cracking tendency is easily generated, so that the reduction of the mechanical property is brought. It was also found that VN after the addition of Al element was well mixed in the bath and thus distributed more uniformly.

(3) The cladding material of the cold-rolled deburring roller for laser cladding provided by the invention contains 1.5-2% of C, so that on one hand, enough carbide is formed with W, Cr, and on the other hand, a certain amount of C is dissolved in austenite, so that the high strength of a martensite matrix is ensured. 4.5 to 6 percent of Co and 10 to 13 percent of W, so that the tissue has red hardness and meets the requirement of high hardness retention capacity under high-speed friction heat. VC can be separated out during the tempering process of V to generate secondary hardening effect.

(4) The repairing method provided by the invention has the advantages of large cladding layer thickness, good anti-pressing performance, higher red hardness maintaining capability, environment friendliness, no damage to the environment, repeated grinding utilization, improvement on the use efficiency of the roller, reduction in roller consumption, improvement on the continuous operation rate of a unit and reduction in repairing cost for enterprises.

Drawings

FIG. 1 is a scanning electron micrograph of the preferred particle size range.

FIG. 2 is a scanning electron micrograph of the initially selected particle size range.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The design scheme of the material has an important index range for the optimization of the powder granularity, the proper grain diameter has a very important influence on the tissue uniformity and the grain refinement, and the macro expression is on the anti-intrusion capability and the fatigue performance.

Proportioning and mixing of alloy powder: aiming at the working conditions of strong pressing force, abrasion, thermal fatigue and the like in the application of the deburring roller, the iron-based self-fluxing alloy mixed powder with excellent abrasion resistance, high hardness and good thermal fatigue resistance is selected as a functional layer repairing material. Wherein the mass fraction of VN is: 1.3 percent; the mass fraction of Al is: 0.5 percent; the iron-based alloy powder comprises the following chemical components in percentage by mass: 1.6% of C, 4.5% of Cr, 3% of V, 5% of Co, 11% of W and the balance of Fe. Preferably VN powder with two different granularities, wherein the first VN powder is-500 to +800 meshes in granularity and more than 99% in purity, and the second VN powder is-100 to +325 meshes in granularity; the preferred granularity of the Al powder is-200 to +300 meshes, and the purity is more than 99 percent; the preferred particle size of the iron-based alloy powder is-125 to +300 meshes.

FIG. 1 shows the preferred particle size range, and the added VN and the matrix are integrated, so that not only is the matrix strengthened and the hardness improved, but also the particles are added to form new core particles, the crystal grains are refined, and new finer wear-resistant particles are formed; FIG. 2 shows the range of the primary particle size, which is too coarse, the size of the wear-resistant particles is large, the function of the reinforcing matrix is not obvious, and the large particles are easy to fatigue and peel off as the wear-resistant support for a long time.

Making fatigue samples for comparison, and under the same working condition, the contact pressure is 3500N/mm²The rotating speed is 2000r/min, after the test is finished, the contact surface of the former has no obvious change by microscope observation, and after the latter is subjected to the contact test, the surface of the latter is fluffy, fine cracks are formed around the particles with large particle size, and the fatigue performance is lower.

Example 1.

A method for repairing a first steel cold-rolled deburring roller by laser cladding comprises the following steps.

Step 1, proportioning and mixing alloy powder: aiming at the working conditions of strong pressing force, abrasion, thermal fatigue and the like in the application of the deburring roller, the iron-based self-fluxing alloy mixed powder with excellent abrasion resistance, high hardness and good thermal fatigue resistance is selected as a functional layer repairing material. Wherein the mass fraction of VN is: 1.3 percent; the mass fraction of Al is: 0.5 percent; the iron-based alloy powder comprises the following chemical components in percentage by mass: 1.6% of C, 4.5% of Cr, 4% of V, 5% of Co, 11% of W and the balance of Fe. Wherein the VN powder has a granularity of-500 to +800 meshes and a purity of more than 99 percent; the granularity of the Al powder is-200 to +300 meshes, and the purity is more than 99 percent; the granularity of the iron-based alloy powder is-125 to +300 meshes.

And 2, mixing the powder by using a powder mixer for not less than 2 hours.

Step 3, pretreatment of the deburring roller before repair: the failed deburring roller needs to be integrally ground to remove the original chromium coating, then fatigue layer machining is carried out, and the machined deburring roller is subjected to dye check to ensure that the surface of the deburring roller has no defects such as cracks, air holes, impurities and the like.

Step 4, deburring roller repairing: the flaw-detected defect-free deburring roller needs to be preheated at the temperature of 200 ℃. And after the preheating temperature is reached, carrying out laser cladding repair work. Selecting a fiber-hung laser, wherein the specific process parameters comprise the powder feeding amount of 18g/min, the laser power of 3kw, the spot diameter of 3.6mm, the scanning speed of 1000mm/min, the stepping of 1.7mm, the lap joint rate of 50% and the single-layer cladding thickness of 1.0 mm; and then grinding the deburring roller to restore the deburring roller to the precision requirement of original drawing paper, and finally, the roughness requirement of the drawing is met through a sand blasting process.

Through the detection of the repaired functional layer, the hardness can reach about 62HRC +/-1, the anti-intrusion performance is greatly improved, no pit is generated after the functional layer is used for 2 months, the functional layer has higher hardness retention capacity, and the service life of the functional layer can be prolonged by more than 1 time.

Example 2.

A method for repairing a first steel cold-rolled deburring roller by laser cladding comprises the following steps.

Step 1, proportioning and mixing alloy powder: aiming at the working conditions of strong pressing force, abrasion, thermal fatigue and the like in the application of the deburring roller, the iron-based self-fluxing alloy mixed powder with excellent abrasion resistance, high hardness and good thermal fatigue resistance is selected as a functional layer repairing material. Wherein the mass fraction of VN is: 1.5 percent; the mass fraction of Al is: 0.7 percent; the iron-based alloy powder comprises the following chemical components in percentage by mass: 1.7% of C, 4.5% of Cr, 4.5% of V, 5.2% of Co, 12% of W and the balance of Fe. Wherein the VN powder has a granularity of-500 to +800 meshes and a purity of more than 99 percent; the granularity of the Al powder is-200 to +300 meshes, and the purity is more than 99 percent; the granularity of the iron-based alloy powder is-125 to +300 meshes.

And 2, mixing the powder by using a powder mixer for not less than 2 hours.

Step 3, pretreatment of the deburring roller before repair: the failed deburring roller needs to be integrally ground to remove the original chromium coating, then fatigue layer machining is carried out, and the machined deburring roller is subjected to dye check to ensure that the surface of the deburring roller has no defects such as cracks, air holes, impurities and the like.

Step 4, deburring roller repairing: the flaw-detected defect-free deburring roller needs to be preheated at the temperature of 200 ℃. And after the preheating temperature is reached, carrying out laser cladding repair work. Selecting a fiber-hung laser, wherein the specific process parameters comprise powder feeding amount of 22g/min, laser power of 3kw, spot diameter of 3.6mm, scanning speed of 1000mm/min, stepping of 1.7mm, lap joint rate of 50% and single-layer cladding thickness of 1.3 mm; and then grinding the deburring roller to restore the deburring roller to the precision requirement of original drawing paper, and finally, the roughness requirement of the drawing is met through a sand blasting process.

Through the detection of the repaired functional layer, the hardness can reach about 62HRC +/-1, the anti-intrusion performance is greatly improved, no pit is generated after the functional layer is used for 2 months, the functional layer has higher hardness retention capacity, and the service life of the functional layer can be prolonged by more than 1 time.