CN114774815B - Laser melting process beneficial to improving wear resistance of alloy - Google Patents
Laser melting process beneficial to improving wear resistance of alloy Download PDFInfo
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Abstract
The invention discloses a laser melting process beneficial to improving the wear resistance of an alloy, which is used for carrying out laser melting treatment on the surface of a magnesium alloy to improve the wear resistance, and the laser melting treatment parameters are designed as follows: the laser power is 110W-160W, the laser scanning speed is 1mm/s-3mm/s, the frequency is 10Hz-60Hz, the spot diameter is 100 mu m-3mm, the pulse width is 5ms-10ms, and the energy density is 36.67J/mm 2 ‑160J/mm 2 . The application improves the wear resistance of the magnesium alloy and is suitable for application in magnesium alloy thin components.
Description
Technical Field
The invention relates to the technical field of metal surface treatment, in particular to a laser melting process beneficial to improving the wear resistance of an alloy.
Background
The magnesium alloy has the advantages of high specific stiffness, high specific strength, good magnetic shielding performance and the like, is suitable for light structural members, is easy to recycle, has strong environmental protection property, is known as a '21 st century green engineering metal structural material', and has obvious competitive advantages and application prospects in the fields of 3C products, aerospace, artificial intelligence, national defense war industry and the like. However, the magnesium alloy matrix has low absolute hardness and is easy to generate plastic deformation, so that the surface has poor wear resistance, and the wear resistance under specific working conditions cannot be met. Its poor abrasion resistance severely limits its range of applications.
In recent years, with the pursuit of improving the performance of metal materials, the application and development of surface modification treatment technologies represented by laser surface impact strengthening, laser surface alloying, laser surface melting, laser surface cladding and the like are promoted, and the attention and research of professionals in the required industry fields are attracted. When the laser beam has high energy density and acts on the surface of the magnesium alloy, the metallurgical, mechanical, physical and other properties of the surface of the magnesium alloy can be improved by virtue of the processes of instant melting and rapid solidification of the magnesium alloy within a certain thickness range by virtue of the good heat conductivity of the magnesium alloy, so that the surface of the magnesium alloy has unique properties. In addition, by applying a laser beam with proper power to the surface of the material, the surface grain structure is obviously refined and has a fused layer with a certain depth, and the research shows that the laser beam and the matrix form a gradient structure together. A gradient structure is a structure in which one component, organization or phase (or component) gradually transits to another component, organization or phase (or component) or a structure in which the size of structural units in a material is changed in a spatial gradient. Due to the structure, the material can not cause great change of performance due to the difference of the size, and the structures with larger size difference can be mutually coordinated, so that the surface service performance and the overall performance of the material are improved.
However, laser shock surface strengthening, laser surface alloying and laser surface cladding require coating a layer of chemical additive or pre-placing alloy powder on the surface of the magnesium alloy, and then the surface performance of the magnesium alloy can be improved by utilizing the action of laser beams. Meanwhile, the laser power adopted by the magnesium alloy laser surface modification treatment mostly exceeds 1KW, the laser modification layer thickness is usually larger than 1mm due to large power, and the ideal effect can be achieved only when the magnesium alloy is required to be thick. The existence of the two reasons causes high production cost, is not favorable for batch production, and cannot meet the application of laser surface treatment in magnesium alloy thin members (less than 1 mm). Compared with the three laser surface technologies, laser surface melting does not need external substances, laser beams directly act on the surface of a magnesium alloy material, and the material cost is saved, but most of laser power of current laser melting research exceeds 1KW, and the thickness requirement exists, so that the application of the laser melting research to magnesium alloy thin members is limited, and the pursuit of light weight and thinness of magnesium alloy is further restricted.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: in order to improve the wear resistance of the magnesium alloy, the laser power adopted by the prior laser surface treatment is higher, and the laser surface treatment is not suitable for being applied to magnesium alloy thin members (the invention provides a laser melting process which is beneficial to improving the wear resistance of the alloy and solves the problems, and the laser melting process is suitable for the magnesium alloy thin members with the thickness of more than 200 mu m.
The invention is realized by the following technical scheme:
a laser melting process beneficial to improving the wear resistance of an alloy, which is used for carrying out laser melting treatment on the surface of a magnesium alloy to improve the wear resistance, and the laser melting treatment parameters are designed as follows: the laser power is 110W-160W, the laser scanning speed is 1mm/s-3mm/s, the frequency is 10Hz-60Hz, the spot diameter is 100 mu m-3mm, the pulse width is 5ms-10ms, and the energy density is 36.67J/mm 2 -160J/mm 2 。
The invention is very important to the control of the scanning speed and frequency, and the over low speed causes the long retention time of the laser on the surface and the high surface absorption energy, which may cause the phenomena of large evaporation and collapse of magnesium element; the speed is too high, so that the residence time of the laser on the surface is short, the surface absorption energy is low, the surface cannot be fully remelted, and the surface cannot reach the ideal thickness. Too high frequency easily results in too thick depth of the fused layer; and the frequency is too low, the depth of the remelting layer is shallow, and the effect of melting cannot be achieved.
Further optionally, the laser consolidation process parameters are designed as: the laser power is 120W-150W, the laser scanning speed is 2mm/s-3mm/s, the frequency is 20Hz-50Hz, the spot diameter is 1mm-3mm, the pulse width is 5ms-10ms, and the energy density is 40J/mm 2 -75J/mm 2 。
Further optionally, the laser consolidation process parameters are designed as: the laser power is 130W-140W, the laser scanning speed is 2mm/s-3mm/s, the frequency is 30Hz-40Hz, the spot diameter is 1mm-3mm, the pulse width is 5ms-10ms, and the energy density is 43.33J/mm 2 -70J/mm 2 。
Further optionally, the method also comprises the step of overlapping the steel plate by 50% in multiple times, wherein the peak value is 1.1-1.6KW.
Further optionally, the defocusing amount is 0-10mm.
Further optionally, the magnesium alloy comprises an AZ80 magnesium alloy.
Further optionally, the magnesium alloy further comprises an AZ31 magnesium alloy or an AZ91 magnesium alloy.
Further alternatively, after the laser fusing treatment, the effective depth of a fused layer formed on the surface of the magnesium alloy is 100-300 μm.
Further alternatively, after the laser melting treatment, the magnesium alloy has three areas with different crystal grain sizes in cross section.
Further optionally, comprising the steps of:
laser working surface pretreatment:
carrying out ultrasonic cleaning on a magnesium alloy sample to be processed; then, grinding the surface of the sample by using sand paper; finally, ultrasonic cleaning is carried out again, and the mixture is dried for standby;
laser processing of the magnesium alloy surface:
under the protection of inert atmosphere, keeping the vacuum degree to set the vacuum degree; starting a laser, loading voltage, and carrying out laser surface fusing treatment on the surface of the AZ80 magnesium alloy material vertical to the extrusion direction according to the set processing parameters; and finally, taking out the sample after the temperature of the sample is reduced to be below 30 ℃.
The invention has the following advantages and beneficial effects:
1. the invention adopts the laser melting method to treat the magnesium alloy surface, and improves the laser melting process to improve the wear resistance of the magnesium alloy, and the sample obtained by the invention has the advantages of no crack on the surface, uniform tissue and obviously improved surface wear resistance. In addition, there are few reports on improving the wear resistance of magnesium alloys using laser melting.
2. The process adopted by the invention is simple, and the cross section can be in three areas (as shown in figure 1) with the grain size by controlling the laser parameters, which is not reported at present.
3. The invention adopts low-power pulse laser, the thickness of the fused layer is only hundreds of microns, the effective depth of the fused layer is between 100 and 300 microns, the fused layer is well combined with a matrix, the stability is high, and the invention is suitable for magnesium alloy components with thin thickness.
4. The invention is green and environment-friendly, does not need additional chemical additives and alloy powder, and does not have any pollution discharge problem; in addition, the invention has the advantages of high processing speed, remarkably improved production efficiency and reduced cost.
5. The laser melting process provided by the invention is suitable for surface treatment of magnesium alloy, such as AZ80 magnesium alloy, and similar materials, such as AZ31 magnesium alloy or AZ91 magnesium alloy; however, with other products, the same laser process parameters are expected to be very remote due to the large structural and textural differences.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
FIG. 1 is a physical representation of a laser fusion processed sample of example 3 of the present invention.
FIG. 2 is a metallographic structure diagram of a cross section of a sample after laser melting processing in example 3 of the present invention.
FIG. 3 is the scanning drawings of the grinding traces of the original sample and the laser sample in example 3 of the present invention, wherein (a), (c) are the original samples and (b) and (d) are the laser samples.
FIG. 4 is a diagram of the wear scar of the original sample and the laser sample in example 3 of the present invention: (a) And (b) the two-dimensional and three-dimensional shapes of the original surface grinding marks are respectively; (c) And (d) laser surface grinding mark two-dimensional and three-dimensional shapes respectively; (e) wear scar depth profile; (f) wear volume statistics.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and the accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not used as limiting the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: it is not necessary to employ these specific details to practice the present invention. In other instances, well-known structures, circuits, materials, or methods have not been described in detail in order to avoid obscuring the present invention.
Throughout the specification, reference to "one embodiment," "an embodiment," "one example," or "an example" means: the particular features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the invention. Thus, the appearances of the phrase "one embodiment," "an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will appreciate that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In the description of the present invention, the terms "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "upper", "lower", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and therefore, should not be construed as limiting the scope of the present invention.
Example 1
The embodiment provides a laser melting process beneficial to improving the wear resistance of an alloy, and the specific steps are as follows:
step 1: cutting a magnesium alloy base material:
a AZ80 magnesium alloy bar is cut into a cylindrical sheet with the thickness of 2mm by utilizing linear cutting, and then samples with the length and the width of 10mm are cut on a circular surface, wherein the surface with the length and the width is a laser working surface.
Step 2: laser working surface pretreatment:
putting the cut samples into a beaker filled with absolute ethyl alcohol, carrying out ultrasonic cleaning for 5min, and blowing the samples dry by a blower in a cold air gear; then, using 600# SiC black sand paper to polish the surface of the sample to obtain a surface which has certain roughness and is completely removed with surface oxide scale; and finally, carrying out ultrasonic cleaning for 5min, and blowing the sample to be processed by using a blower to blow the sample at a cold air gear.
And step 3: laser processing of the surface of the magnesium alloy base material:
fixing the polished sample on a YAG laser sample table, introducing 99.9% argon into a working chamber to prevent the sample from being oxidized in the laser processing process, and filling gas with vacuum degree of 5 × 10 -3 Pa。
Then setting laser parameters and setting laser beam paths. And starting a laser, loading voltage, and carrying out laser surface fusing treatment on the surface of the AZ80 magnesium alloy material vertical to the extrusion direction. The laser surface treatment process parameters are as follows: the laser power is 110W, the laser scanning speed is 1mm/s, the frequency is 60Hz, the defocusing amount is 1mm, the diameter of a light spot is 1mm, the multi-pass overlapping rate is 50 percent, the peak value is 1.1KW, the pulse width is 8ms, and the energy density is 110J/mm 2 . And finally, taking out the sample after the temperature of the sample is reduced to be below 30 ℃.
And (4) performance testing:
and (4) sequentially polishing the laser processing sample obtained in the step (3) by using 600# black SiC abrasive paper, (500 #, 1000#, 2000# and 4000 #) dry and wet green SiC abrasive paper, then polishing by using a 200r/min polishing machine, and uniformly coating 0.5 mu m diamond polishing paste on the surface of the polishing cloth to obtain a bright surface without obvious scratches. Followed by wear performance testing.
Under a sliding abrasion tester, an abrasion test is carried out by applying a load of 5N, and the result of detection shows that the volume of the abrasion rate is reduced by 10 percent.
Example 2
The embodiment provides a laser melting process beneficial to improving the wear resistance of an alloy, and the specific steps are as follows:
step 1: cutting a magnesium alloy base material:
a AZ80 magnesium alloy bar is cut into a cylindrical sheet with the thickness of 2mm by utilizing linear cutting, and then samples with the length and the width of 10mm are cut on a circular surface, wherein the surface with the length and the width is a laser working surface.
Step 2: laser working surface pretreatment:
putting the cut samples into a beaker filled with absolute ethyl alcohol, carrying out ultrasonic cleaning for 5min, and blowing the samples dry by a blower in a cold air gear; then, using 600# SiC black sand paper to polish the surface of the sample to obtain a surface which has certain roughness and is completely removed with surface oxide scale; and finally, carrying out ultrasonic cleaning for 5min, and blowing the sample by using a blower in a cold air gear to be used as a laser sample to be processed.
And 3, step 3: laser processing of the surface of the magnesium alloy substrate:
fixing the polished sample on a YAG laser sample table, introducing 99.9% argon into a working chamber to prevent the sample from being oxidized in the laser processing process, and filling gas with vacuum degree of 5 × 10 -3 Pa。
Then setting laser parameters and setting laser beam paths. And starting a laser, loading voltage, and carrying out laser surface fusing treatment on the surface of the AZ80 magnesium alloy material vertical to the extrusion direction. The laser surface treatment process parameters are as follows: the laser power is 150W, the laser scanning speed is 3mm/s, the frequency is 20Hz, the defocusing amount is 1mm, the diameter of a light spot is 1mm, the multi-pass overlapping rate is 50%, the peak value is 1.5KW, the pulse width is 5ms, and the energy density is 50J/mm. Finally, the sample is taken out after the temperature of the sample is reduced to below 30 ℃ (the physical diagram is shown in figure 1).
And (3) performance testing:
and (4) sequentially polishing the laser processing sample obtained in the step (3) by using 600# black SiC abrasive paper, (500 #, 1000#, 2000# and 4000 #) dry and wet green SiC abrasive paper, then polishing by using a 200r/min polishing machine, and uniformly coating 0.5 mu m diamond polishing paste on the surface of the polishing cloth to obtain a bright surface without obvious scratches. Followed by wear performance testing.
The abrasion test was carried out under a sliding abrasion tester under a load of 5N, and as a result, it was found that the abrasion volume was decreased by 25%.
Example 3
The embodiment provides a laser melting process beneficial to improving the wear resistance of an alloy, and the specific steps are as follows:
step 1: cutting a magnesium alloy base material:
a AZ80 magnesium alloy bar is cut into a cylindrical sheet with the thickness of 2mm by utilizing linear cutting, and then samples with the length and the width of 10mm are cut on a circular surface, wherein the surface with the length and the width is a laser working surface.
Step 2: laser working surface pretreatment:
putting the cut samples into a beaker filled with absolute ethyl alcohol, carrying out ultrasonic cleaning for 5min, and blowing the samples dry by a blower in a cold air gear; then, grinding the surface of the sample by using 600# SiC black sand paper to obtain a surface which has certain roughness and is completely removed with surface scale; and finally, carrying out ultrasonic cleaning for 5min, and blowing the sample by using a blower in a cold air gear to be used as a laser sample to be processed.
And step 3: laser processing of the surface of the magnesium alloy base material:
fixing the polished sample on a YAG laser sample table, introducing 99.9% argon gas into a working chamber to prevent the sample from being oxidized in the laser processing process, and filling gas with vacuum degree of 5 × 10 -3 Pa。
Then setting laser parameters and setting laser beam paths. And starting a laser, loading voltage, and carrying out laser surface fusing treatment on the surface of the AZ80 magnesium alloy material vertical to the extrusion direction. The laser surface treatment process parameters are as follows: 130W of laser power, 2mm/s of laser scanning speed, 30Hz of frequency, 1mm of defocusing amount, 1mm of spot diameter, 50% of multi-pass overlapping rate, 1.3KW of peak value, 5ms of pulse width and 65J/mm of energy density 2 . Finally, the sample is taken out after the temperature of the sample is reduced to below 30 ℃ (the physical diagram is shown in figure 1). And (3) performance testing:
and (3) sequentially polishing the laser processing sample obtained in the step (3) by using 600# black SiC abrasive paper, (500 #, 1000#, 2000# and 4000 #) dry-wet green SiC abrasive paper, then polishing by using a 200r/min polishing machine, and uniformly coating 0.5 mu m diamond polishing paste on the surface of the polishing cloth to obtain a bright surface without obvious scratches. Subsequent organizational characterization and performance testing was then performed.
The results obtained were:
a. metallographic phase display structure: from the cross-sectional metallographic phase (as shown in fig. 2), the grain size of the cross-section clearly shows three regions, which are from outside to inside: the crystal grains on the outer surface are the smallest (fine crystal area), and the widest thickness of the crystal grains can reach 167 mu m; the area (transition area) bordering on the matrix is slightly larger in grain size, the widest thickness of the area can reach 70 mu m, but the area is obviously thinner than the matrix; matrix, crystal grain is largest.
b. And (3) wear performance testing: the abrasion test shows that: the abrasion degree of the original sample is obviously worse than that of the laser sample, the grinding crack width of the original sample is 1324 mu m, while the grinding crack width of the laser sample is only 774 mu m, and the grinding crack width of the laser sample is obviously narrower. (as shown in FIG. 3);
as further seen from the two-dimensional and three-dimensional profiles, the original sample width was about 1100 μm, while the laser sample was about 750 μm, with results consistent with those shown in FIG. 3; the three-dimensional topography shows that the original sample was ground to a depth of 50 μm, whereas the laser sample was only 30 μm. The cross-sectional width curves show the difference in transverse cross-sectional width, with the original sample having a wear scar depth of about 25 μm and the laser sample having only 5 μm. The wear volume of the original sample was 5.00X 10 4 μm 3 And the laser sample has a wear volume of 2.60X 10 4 μm 3 The wear volume was reduced by 48%.
Example 4
The embodiment provides a laser melting process beneficial to improving the wear resistance of an alloy, and the specific steps are as follows:
step 1: cutting a magnesium alloy base material:
a AZ80 magnesium alloy bar is cut into a cylindrical sheet with the thickness of 2mm by utilizing linear cutting, and then samples with the length and the width of 10mm are cut on a circular surface, wherein the surface with the length and the width is a laser working surface.
And 2, step: laser working surface pretreatment:
putting the cut samples into a beaker filled with absolute ethyl alcohol, carrying out ultrasonic cleaning for 5min, and blowing the samples dry by a blower in a cold air gear; then, grinding the surface of the sample by using 600# SiC black sand paper to obtain a surface which has certain roughness and is completely removed with surface scale; and finally, carrying out ultrasonic cleaning for 5min, and blowing the sample to be processed by using a blower to blow the sample at a cold air gear.
And step 3: laser processing of the surface of the magnesium alloy substrate:
fixing the polished sample on YIntroducing 99.9% argon into a working chamber of an AG laser sample stage to avoid sample oxidation in the laser processing process, wherein the vacuum degree of the introduced gas is 5 multiplied by 10 -3 Pa。
Then setting laser parameters and setting laser beam paths. And starting a laser, loading voltage, and carrying out laser surface fusing treatment on the surface of the AZ80 magnesium alloy material vertical to the extrusion direction. The laser surface treatment process parameters are as follows: the laser power is 120W, the laser scanning speed is 3mm/s, the frequency is 50Hz, the defocusing amount is 1mm, the diameter of a light spot is 1mm, the multi-pass overlapping rate is 50%, the peak value is 1.2KW, the pulse width is 5ms, and the energy density is 40J/mm. And finally, taking out the sample after the temperature of the sample is reduced to be below 30 ℃.
The fused thickness was found to be only about 150 μm, and the abrasion volume was found to decrease by only 15% as a result of abrasion test under a sliding abrasion tester with a load of 5N.
The present comparative test provides a method for processing a magnesium alloy surface by a laser melting process, which comprises the following steps:
step 1: cutting a magnesium alloy base material:
a AZ80 magnesium alloy bar is cut into cylindrical pieces with the thickness of 2mm by linear cutting, and then samples with the length and the width of 10mm are cut on a circular surface, wherein the surface with the length and the width is a laser working surface.
Step 2: laser working surface pretreatment:
putting the cut samples into a beaker filled with absolute ethyl alcohol, carrying out ultrasonic cleaning for 5min, and blowing the samples to dry by using a blower in a cold air gear; then, using 600# SiC black sand paper to polish the surface of the sample to obtain a surface which has certain roughness and is completely removed with surface oxide scale; and finally, carrying out ultrasonic cleaning for 5min, and blowing the sample to be processed by using a blower to blow the sample at a cold air gear.
And step 3: laser processing of the surface of the magnesium alloy base material:
fixing the polished sample on a YAG laser sample table, introducing 99.9% argon into a working chamber to prevent the sample from being oxidized in the laser processing process, and filling gas into the working chamber to ensure that the vacuum degree is highIs 5 x 10 -3 Pa。
Then setting laser parameters and setting laser beam paths. And starting a laser, loading voltage, and carrying out laser surface fusing treatment on the surface of the AZ80 magnesium alloy material vertical to the extrusion direction. The laser surface treatment process parameters are as follows: the laser power is 170W, the laser scanning speed is 5mm/s, the frequency is 80Hz, the defocusing amount is 1mm, the diameter of a light spot is 1mm, the multi-pass overlapping rate is 50%, the peak value is 1.7KW, the pulse width is 5ms, and the energy density is 34J/mm. And finally taking out the sample after the temperature of the sample is reduced to be below 30 ℃.
The detection shows that the thickness of the fused layer is about 250 μm, but the surface and the cross section of the fused layer have a large number of micro cracks and pores, and the fused layer has a large number of defects and is unqualified. Under a sliding mill testing machine, a 5N load is applied to carry out an abrasion test, and the result detection shows that the abrasion volume of the abrasion test is not obviously reduced, even the abrasion volume of an experimental group is higher than that of a base material.
Control experiment 2
The present comparative experiment provides a method for processing magnesium alloy surface by laser melting process, which comprises the following steps:
step 1: cutting a magnesium alloy base material:
a AZ80 magnesium alloy bar is cut into cylindrical pieces with the thickness of 2mm by linear cutting, and then samples with the length and the width of 10mm are cut on a circular surface, wherein the surface with the length and the width is a laser working surface.
Step 2: laser working surface pretreatment:
putting the cut samples into a beaker filled with absolute ethyl alcohol, carrying out ultrasonic cleaning for 5min, and blowing the samples to dry by using a blower in a cold air gear; then, using 600# SiC black sand paper to polish the surface of the sample to obtain a surface which has certain roughness and is completely removed with surface oxide scale; and finally, carrying out ultrasonic cleaning for 5min, and blowing the sample to be processed by using a blower to blow the sample at a cold air gear.
And step 3: laser processing of the surface of the magnesium alloy substrate:
fixing the polished sample on a YAG laser sample table, and introducing 99.9% argon gas into a working chamber to prevent the sample from being oxidized in the laser processing processThe degree of vacuum of the charged gas is 5 x 10 -3 Pa。
Then setting laser parameters and setting laser beam paths. And starting a laser, loading voltage, and carrying out laser surface melting treatment on the surface of the AZ80 magnesium alloy material vertical to the extrusion direction. The laser surface treatment process parameters are as follows: the laser power is 100W, the laser scanning speed is 1mm/s, the frequency is 10Hz, the defocusing amount is 1mm, the diameter of a light spot is 1mm, the multi-pass overlapping rate is 50%, the peak value is 1KW, the pulse width is 5ms, and the energy density is 100J/mm. And finally taking out the sample after the temperature of the sample is reduced to be below 30 ℃.
The detection shows that the surface has a serious collapse phenomenon and obvious pits, the depth of the pits is almost close to the thickness of the base material, the energy density is too high, so that a large amount of magnesium element is evaporated, and the subsequent wear test requirements cannot be met.
Control experiment 3
The present comparative test provides a method for processing a magnesium alloy surface by a laser melting process, which comprises the following steps:
step 1: cutting a magnesium alloy base material:
a AZ80 magnesium alloy bar is cut into a cylindrical sheet with the thickness of 2mm by utilizing linear cutting, and then samples with the length and the width of 10mm are cut on a circular surface, wherein the surface with the length and the width is a laser working surface.
Step 2: laser working surface pretreatment:
putting the cut samples into a beaker filled with absolute ethyl alcohol, carrying out ultrasonic cleaning for 5min, and blowing the samples dry by a blower in a cold air gear; then, using 600# SiC black sand paper to polish the surface of the sample to obtain a surface which has certain roughness and is completely removed with surface oxide scale; and finally, carrying out ultrasonic cleaning for 5min, and blowing the sample to be processed by using a blower to blow the sample at a cold air gear.
And step 3: laser processing of the surface of the magnesium alloy base material:
fixing the polished sample on a YAG laser sample table, introducing 99.9% argon gas into a working chamber to prevent the sample from being oxidized in the laser processing process, and filling gas with vacuum degree of 5 × 10 -3 Pa。
Then setting laser parameters and setting laser beam paths. And starting a laser, loading voltage, and carrying out laser surface melting treatment on the surface of the AZ80 magnesium alloy material vertical to the extrusion direction. The laser surface treatment process parameters are as follows: the laser power is 50W, the laser scanning speed is 2mm/s, the frequency is 20Hz, the defocusing amount is 1mm, the diameter of a light spot is 1mm, the multi-pass overlapping rate is 50%, the peak value is 0.5KW, the pulse width is 5ms, and the energy density is 25J/mm. And finally, taking out the sample after the temperature of the sample is reduced to be below 30 ℃.
The detection shows that the thickness of the fused layer is only 80 μm, and the fused layer also has a large amount of micro cracks and pores, and the quality of the fused layer is not qualified. In a sliding abrasion tester, an abrasion test is carried out by applying a load of 5N, and the abrasion volume is reduced by about 5%.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (8)
1. A laser melting process for improving the wear resistance of an alloy, characterized in that the surface of a magnesium alloy is subjected to a laser melting treatment for improving the wear resistance, wherein: the magnesium alloy is a thin component with the thickness of 200 mu m-2 mm, and the laser melting treatment parameters are designed as follows:
the laser power is 110W to 160W, the laser scanning speed is 1mm/s to 3mm/s, the frequency is 10Hz to 60Hz, the spot diameter is 100 mu m to 3m, the pulse width is 5ms to 10ms, and the energy density is 36.67J/mm 2 ~160J/mm 2 ；
The magnesium alloy includes an AZ80 magnesium alloy, an AZ31 magnesium alloy or an AZ91 magnesium alloy.
2. The laser fusing process for improving the wear resistance of the alloy as claimed in claim 1, wherein the laser fusing process parameters are designed as follows:
laser power 120W to 150W, laser scanningThe drawing speed is 2mm/s-3mm/s, the frequency is 20Hz-50Hz, the spot diameter is 1mm-3mm, the pulse width is 5ms-10ms, and the energy density is 40J/mm 2 ~75J/mm 2 。
3. The laser fusing process for improving the wear resistance of the alloy as claimed in claim 2, wherein the laser fusing process parameters are designed as follows:
130W to 140W of laser power, 2mm/s to 3mm/s of laser scanning speed, 30Hz to 40Hz of frequency, 1mm to 3mm of spot diameter, 5ms to 10ms of pulse width and 43.33J/mm of energy density 2 ~70J/mm 2 。
4. The laser melting process facilitating the improvement of the wear resistance of the alloy as claimed in claim 1, further comprising 50% of multi-pass lap joint rate and 1.1 to 1.6kW of peak value.
5. The laser melting process facilitating improvement of the wear resistance of the alloy as claimed in claim 1, further comprising 0-10mm out of focus.
6. The laser fusing process for improving the wear resistance of the alloy as claimed in claim 1, wherein the effective depth of the fused layer formed on the surface of the magnesium alloy after the laser fusing treatment is 100 μm to 300 μm.
7. The laser melting process for improving the wear resistance of alloy as claimed in claim 1, wherein the magnesium alloy has three regions with different grain sizes in cross section after the laser melting treatment.
8. The laser melting process for improving the wear resistance of alloy according to claim 1, comprising the following steps:
laser working surface pretreatment:
carrying out ultrasonic cleaning on a magnesium alloy sample to be processed; then, grinding the surface of the sample by using sand paper; finally, ultrasonic cleaning is carried out again, and the mixture is dried for standby;
laser processing of the magnesium alloy surface:
under the protection of inert atmosphere, keeping the vacuum degree to set the vacuum degree; starting a laser, loading voltage, and carrying out laser surface fusing treatment on the surface of the AZ80 magnesium alloy material vertical to the extrusion direction according to the set processing parameters; and finally taking out the sample after the temperature of the sample is reduced to be below 30 ℃.
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| CN106435424A (en) * | 2016-09-22 | 2017-02-22 | 天津东义镁制品股份有限公司 | Laser shocking method of changing whole performance of AZ31B magnesium alloy |
| CN107164711A (en) * | 2017-04-14 | 2017-09-15 | 北京航空航天大学 | A kind of method that short-pulse laser improves Mg alloy surface corrosion resistance |
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| CN106637018B (en) * | 2016-11-17 | 2018-04-06 | 辽宁工程技术大学 | The method of laser melting and ultrasonic impact local strengthening magnesium alloy high temperature tensile properties |
| CN108555437A (en) * | 2018-05-09 | 2018-09-21 | 北京航空航天大学 | A kind of laser processing of orientation regulation and control biomedical metal material superficial cell growth |
| CN110079850A (en) * | 2019-04-23 | 2019-08-02 | 苏州紫金港智能制造装备有限公司 | The method for improving Mg alloy surface corrosion resisting property based on differential arc oxidation and laser remolten |
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| CN106435424A (en) * | 2016-09-22 | 2017-02-22 | 天津东义镁制品股份有限公司 | Laser shocking method of changing whole performance of AZ31B magnesium alloy |
| CN107164711A (en) * | 2017-04-14 | 2017-09-15 | 北京航空航天大学 | A kind of method that short-pulse laser improves Mg alloy surface corrosion resistance |
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