阅读说明：本技术 一种用于增强连铸机拉矫辊的阻热及耐磨性能的方法及所得拉矫辊 (Method for enhancing heat resistance and wear resistance of withdrawal and straightening roller of continuous casting machine and withdrawal and straightening roller obtained by method ) 是由 孙登月 王朋鹤 许石民 于 2019-09-29 设计创作，主要内容包括：本发明提供了一种用于增强连铸机拉矫辊的阻热及耐磨性能的方法及所得拉矫辊,属于冶金技术工业领域。该方法包括：将质量分数为5.3-13.5％的氧化钇部分稳定的氧化锆粉末与WC20Cr7Ni合金粉末按照质量比1-19：1球磨混合12-36h,得到混合合金粉末；在氩气保护氛围下,采用等离子喷涂方式将混合合金粉末喷涂至带有粘结层的拉矫辊上,形成厚度为100-300μm的混合涂层。通过该方法,能够在保持混合涂层优异的结合强度的同时,有效降低辊面温度,降低轴承及拉矫辊的热损耗,增强拉矫辊耐磨性,提高生产效率。(The invention provides a method for enhancing the heat resistance and wear resistance of a withdrawal and straightening roller of a continuous casting machine and the withdrawal and straightening roller, belonging to the technical field of metallurgy. The method comprises the following steps: mixing 5.3-13.5 mass percent of yttria partially stabilized zirconia powder and WC20Cr7Ni alloy powder according to the mass ratio of 1-19: 1, ball milling and mixing for 12-36h to obtain mixed alloy powder; and spraying the mixed alloy powder onto the pulling and straightening roller with the bonding layer in a plasma spraying manner under the argon protection atmosphere to form a mixed coating with the thickness of 100-300 mu m. By the method, the excellent bonding strength of the mixed coating can be kept, the temperature of the roll surface can be effectively reduced, the heat loss of the bearing and the pulling and straightening roll can be reduced, the wear resistance of the pulling and straightening roll can be enhanced, and the production efficiency can be improved.)

1. A method for enhancing the heat resistance and wear resistance of a withdrawal and straightening roll of a continuous casting machine, which is characterized by comprising the following steps:

mixing 5.3-13.5 mass percent of yttria partially stabilized zirconia powder and WC20Cr7Ni alloy powder according to the mass ratio of 1-19: 1, ball milling and mixing for 12-36h to obtain mixed alloy powder;

and spraying the mixed alloy powder onto a pulling and straightening roller with a bonding layer in a plasma spraying manner under the argon protection atmosphere to form a mixed coating with the thickness of 100-300 mu m.

2. The method for enhancing the heat and wear resistance of the withdrawal roll of a continuous casting machine according to claim 1, wherein the bonding layer is formed by spraying MCrAlY alloy powder on the surface of the withdrawal roll by means of plasma spraying, and the surface of the withdrawal roll needs to be flat and has hardness lower than 60 HRC.

3. The method for enhancing the heat resistance and wear resistance of the withdrawal roll of the continuous casting machine as claimed in claim 1, wherein the thickness of the bonding layer is 100-200 μm.

4. The method for enhancing the heat resistance and the wear resistance of the withdrawal and straightening roller of the continuous casting machine according to claim 2, wherein the technological parameters for preparing the bonding layer by adopting a plasma spraying mode comprise the following steps: the current is 500-650A, the voltage is 75-85V, the spraying distance is 50-100mm, and the powder feeding rate is 20-50 g/min.

5. The method of claim 1, wherein the yttria-partially stabilized zirconia powder comprises 5.3 to 13.5% by weight Y₂O₃With 86.5-94.7 percent of ZrO₂The particle size of the yttria-partially stabilized zirconia powder is 15-45 μm.

6. The method for enhancing the heat resistance and wear resistance of the withdrawal roll of the continuous casting machine as claimed in claim 1, wherein the WC20Cr7Ni alloy powder contains a high-hardness tungsten-based cladding powder of 20 mass% of chromium, 7 mass% of nickel and 73 mass% of tungsten carbide, and the WC20Cr7Ni alloy powder has a particle size of 20 to 45 μm.

7. The method for enhancing the heat resistance and the wear resistance of the withdrawal and straightening roller of the continuous casting machine according to claim 1, wherein the process parameters for preparing the mixed coating by adopting a plasma spraying mode comprise the following steps: the current is 500-600A, the voltage is 80-85V, the spraying distance is 60-80mm, the powder feeding rate is 20-40g/min, and the Ar gas flow is 40-90L/min.

8. The method of claim 1 wherein the hybrid coating is applied at locations on the roll surface of the withdrawal roll and at the junction of the withdrawal roll and the bearing.

9. A withdrawal and straightening roller of a continuous casting machine with strong heat resistance and wear resistance, which is characterized by comprising a withdrawal and straightening roller base body, a bonding layer and a mixed coating, wherein the bonding layer is positioned between the withdrawal and straightening roller base body and the mixed coating, the thickness of the mixed coating is 100-300 mu m, and the mixed coating is prepared by the method for enhancing the heat resistance and wear resistance of the withdrawal and straightening roller according to any one of claims 1-8.

Technical Field

The invention relates to the technical field of powder metallurgy, in particular to a method for enhancing the heat resistance and wear resistance of a withdrawal and straightening roller of a continuous casting machine and the withdrawal and straightening roller.

Background

The withdrawal and straightening roller of the continuous casting machine is an important part in the continuous casting machine, the working condition of the withdrawal and straightening roller is quite severe, and the withdrawal and straightening roller needs to drag a thick plate blank to move in production and is positioned in complex environments of high temperature, much water, much steam and the like, so the service life of the roller is short, and the consumption is high. At present, the withdrawal and straightening roller of the continuous casting machine generally adopts a core water-cooling external surfacing mode, and has high processing difficulty and high maintenance cost. Under the working condition of high temperature and water cooling alternation, the thermal fatigue life of the roller is short, particularly, the pulling and straightening roller in the secondary cooling area needs to be overhauled and replaced every 1-2 months, the replaced roller is subjected to surface treatment and then is subjected to surfacing welding of 0Cr13Ni4Mo, the whole process is time-consuming, and the production cost is increased. The heat resistance is an important way for further prolonging the service life of the pulling and straightening roller.

At present, the service life of a lifting straightening and withdrawal roll is reported at home and abroad, for example, in patent CN 201821265763.9, the service life of the straightening and withdrawal roll is mainly prolonged through structural design, but the processing difficulty is large, and the cost is high; in the patent CN201410111086.5, the zirconia coating is adopted, although the heat resistance is improved to a certain extent, the wear resistance is still not good, and it is difficult to improve the service life of the pulling and straightening roll.

In view of the above, the present application provides a method for enhancing the heat and wear resistance of a pulling roll and the resulting pulling roll to overcome the above-described problems.

Disclosure of Invention

The invention aims to provide a method for enhancing the heat resistance and wear resistance of a withdrawal and straightening roller of a continuous casting machine and the withdrawal and straightening roller obtained by the method.

In order to achieve the above purpose of the present invention, the following technical solutions are adopted:

a method for enhancing the heat and wear resistance of a pulling roll comprising:

mixing 5.3-13.5 mass percent of yttria partially stabilized zirconia powder and WC20Cr7Ni alloy powder according to the mass ratio of 1-19: 1, ball milling and mixing for 12-36h to obtain mixed alloy powder;

and spraying the mixed alloy powder onto a pulling and straightening roller with a bonding layer in a plasma spraying manner under the argon protection atmosphere to form a mixed coating with the thickness of 100-300 mu m.

Further, in the preferred embodiment of the present invention, the bonding layer is formed by plasma spraying the MCrAlY alloy powder onto the surface of the pulling and straightening roll, which needs to be flat and have a hardness of less than 60 HRC.

Further, in the preferred embodiment of the present invention, the thickness of the bonding layer is 100-200 μm.

Further, in a preferred embodiment of the present invention, the process parameters for preparing the bonding layer by plasma spraying include: the current is 500-650A, the voltage is 75-85V, the spraying distance is 50-100mm, and the powder feeding rate is 20-50 g/min.

Further, in a preferred embodiment of the present invention, the yttria-partially stabilized zirconia powder comprises 5.3 to 13.5 mass% of Y₂O₃With 86.5-94.7 percent of ZrO₂The particle size of the yttria-partially stabilized zirconia powder is 15-45 μm.

Further, in a preferred embodiment of the present invention, the WC20Cr7Ni alloy powder contains a high-hardness tungsten-based cladding powder of 20 mass% of chromium, 7 mass% of nickel, and 73 mass% of tungsten carbide, and the particle size of the WC20Cr7Ni alloy powder is 20 to 45 μm.

Further, in a preferred embodiment of the present invention, the process parameters for preparing the hybrid coating by plasma spraying include: the current is 500-600A, the voltage is 80-85V, the spraying distance is 60-80mm, the powder feeding rate is 20-40g/min, and the Ar gas flow is 40-90L/min.

Further, in the preferred embodiment of the invention, the spraying position of the mixed coating is the roll surface of the pulling and straightening roll and the joint of the pulling and straightening roll and the bearing.

A withdrawal and straightening roller of a continuous casting machine with strong heat resistance and wear resistance, which comprises a withdrawal and straightening roller base body, a bonding layer and a mixed coating, wherein the bonding layer is positioned between the withdrawal and straightening roller base body and the mixed coating, the thickness of the mixed coating is 100-300 mu m, and the mixed coating is prepared by the method for enhancing the heat resistance and wear resistance of the withdrawal and straightening roller according to any one of claims 1 to 8.

Compared with the prior art, the invention has the beneficial effects that:

the method for enhancing the heat resistance and the wear resistance of the pulling and straightening roller of the continuous casting machine improves the service life of the pulling and straightening roller and bearings at two ends by spraying the zirconium oxide/tungsten carbide mixed coating on the roller surface of the pulling and straightening roller and the joints of the bearings at two ends of the pulling and straightening roller. Wherein, the heat conductivity coefficient of the zirconia is one tenth of that of common steel, and the zirconia has high stability and high strength at high temperature; the tungsten carbide has high temperature resistance and good wear resistance, and the tungsten carbide are attached to the surface of the straightening and withdrawal roll by a plasma spraying method according to a certain proportion to form a mixed coating. The application of the zirconium oxide/tungsten carbide mixed coating can well combine the coating performances of two materials, so that the surface temperature drop of the pulling and straightening roller can reach 60-200 ℃, and meanwhile, the excellent bonding strength is kept. Compared with the currently commonly applied surfacing process (400HV), the micro-hardness of the zirconium oxide/tungsten carbide mixed coating is obviously improved, and in addition, the coating has excellent thermal shock resistance. Therefore, the pulling and straightening roller prepared by the method can effectively reduce the temperature of the roller surface, reduce the heat loss of the bearing and the pulling and straightening roller and improve the production efficiency while maintaining the excellent bonding strength of the pulling and straightening roller.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.

FIG. 1 is a block diagram of a spray hybrid coating of the present invention;

FIG. 2 is a metallographic comparison of the hybrid coating of the present invention before and after thermal shock (100 thermal shocks);

FIG. 3 is a schematic diagram of the thermal insulation test of the present invention;

FIG. 4 is the measured results of the cycle temperature rise curves of the coating of the present invention and a single coating;

FIG. 5 is a graph of hybrid coating hardness and single coating hardness according to the present invention; and

fig. 6 is a schematic diagram of a wear-resistant test and a test result.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The features and properties of the present invention are further described in detail below with reference to examples: