阅读说明：本技术 一种钢制零件表面修复方法 (Steel part surface repairing method ) 是由 王行涛 祝弘滨 折洁 刘昱 龚明 于 2021-06-22 设计创作，主要内容包括：本发明提供一种钢制零件表面修复方法,所述方法采用定向能量沉积与轧制复合的方式,其中,轧制温度控制在800～1100℃,轧制压力控制在使沉积层发生压塑性变形,应变为0.1～0.5,变形速率为0.1～1.2s～(-1),所述轧制温度为轧制时沉积区域的表面温度。本发明通过将定向能量沉积与轧制复合,在修复区域边沉积金属边轧制,并同时调控轧制过程中的温度、压力,从而有效的减少沉积金属组织中的气孔、未熔合和裂纹等缺陷,并能细化晶粒,使修复组织更加致密,显著提升修复部分的力学性能和疲劳性能。本发明的方法具有设备简单,加工成本低,加工效率高,不受零件尺寸限制,作用深度深等优点。(The invention provides a steel part surface repairing method which adopts a directional energy deposition and rolling composite mode, wherein the rolling temperature is controlled to be 800-1100 ℃, the rolling pressure is controlled to ensure that a deposition layer generates pressure plastic deformation, the strain is 0.1-0.5, and the deformation rate is 0.1-1.2 s ‑1 And the rolling temperature is the surface temperature of the deposition area during rolling. The invention combines directional energy deposition and rolling, deposits metal in a repair area while rolling, and simultaneously regulates and controls the temperature and the pressure in the rolling process, thereby effectively reducing the defects of pores, unfused fusion, cracks and the like in a deposited metal structure, refining grains, leading the repair structure to be more compact, and obviously improving the mechanical property and the pressure of a repair partFatigue performance. The method has the advantages of simple equipment, low processing cost, high processing efficiency, no limitation of the size of parts, deep action depth and the like.)

1. The method for repairing the surface of the steel part is characterized by adopting a directional energy deposition and rolling composite mode, wherein the rolling temperature is controlled to be 800-1100 ℃, the rolling pressure ensures that the pressure plastic deformation is generated on a deposition layer, the strain is 0.1-0.5, and the deformation rate is 0.1-1.2 s^-1And the rolling temperature is the surface temperature of the deposition area during rolling.

2. The method for repairing the surface of a steel part according to claim 1, wherein the rolling is performed when the surface temperature of the deposition region formed by the directed energy deposition is reduced to 800-1100 ℃.

3. The method for repairing the surface of a steel part according to claim 1 or 2, wherein the surface of the steel part is a plane, an arc surface or a free-form surface.

4. Method for repairing the surface of a steel part according to claim 1, characterized in that it comprises the following steps:

(1) machining the area to be repaired on the surface of the steel part to remove defects, damages and oxide layers;

(2) the high-energy beam processing head guides the high-energy beam to melt the area to be repaired on the surface of the steel part and the metal deposition material, and the high-energy beam processing head melts, solidifies and accumulates layer by layer according to a preset deposition track to form a deposition layer; the method comprises the steps of performing layer-by-layer or interlayer synchronous rolling during deposition, controlling the rolling temperature to be 800-1100 ℃ by adjusting the distance between a high-energy beam processing head and a roller, and controlling the pressure of the roller to enable the deposition layer to generate plastic deformation under the action of pressureThe strain is 0.1-0.5, and the deformation rate is 0.1-1.2 s^-1。

5. The method for repairing the surface of the steel part as recited in claim 4, wherein in the step (2), the synchronous rolling comprises the steps of enabling the moving direction, the moving speed and the moving start-stop time to be consistent, and after the rolling temperature is determined, the relative positions of the high-energy beam processing head and the roller are kept unchanged.

6. The method for repairing the surface of a steel part according to claim 4 or 5, wherein in the step (2), the thickness of the deposition layer between two rolling passes in the synchronous rolling process is not more than 4 mm.

7. The method for repairing the surface of a steel part according to any one of claims 4 to 6, wherein in the step (2), the high-energy beam is a laser, an arc, an electron beam or a plasma beam.

8. The method for repairing the surface of a steel part as claimed in any one of claims 4 to 6, wherein in the step (2), the metal deposition material is steel powder or wire having the same or similar composition as that of the steel part material.

9. The method for repairing the surface of a steel part according to any one of claims 4 to 8, wherein the rolling temperature is controlled to 800 to 910 ℃, the strain of the deposited layer subjected to the pressure plastic deformation under the pressure is 0.2 to 0.5, and the deformation rate is 0.2 to 1.0s^-1。

10. A steel part repaired by the method for repairing a surface of a steel part according to any one of claims 1 to 9.

Technical Field

The invention relates to the field of metal additive manufacturing, in particular to a steel part surface repairing method.

Background

Additive Manufacturing (AM) has attracted wide attention worldwide in recent years, and has become an important development direction of advanced Manufacturing technology, which plays a crucial role in the field of industrial application. Additive manufacturing is a form of manufacturing process that connects Materials together, typically using a layer-by-layer stack, based on 3D model data, in response to subtractive manufacturing, as defined by the American Society for Testing and Materials (ASTM).

Directed Energy Deposition (DED) is an additive manufacturing process that uses focused thermal Energy to melt a molding material and deposit it in a predetermined trajectory to form the desired part. Compared with the traditional manufacturing method, the directional energy deposition can realize the molding of complex metal parts without a die; the traditional equipment such as a cutter, a clamp, a machine tool and the like is not needed; the manufacturing process is short, and the method has the characteristic of distributed production. Compared with the powder bed additive manufacturing methods such as selective laser bed melting and the like, the directional energy deposition can realize deposition molding on the surface of the existing part and is suitable for repairing the part; the forming efficiency and the forming size are higher, and the method is suitable for preparing large-size blank pieces; the method can be used for preparing gradient parts, and the composition and the structure of a specific position can be changed according to the actual use requirement.

But the surface repair of the part directly by a high-energy beam heat source has inherent defects. When the heat source moves along the surface of the part, local overheating is formed on the surface of the part, crystal grains in an overheating area are increased rapidly, and an overheating structure is generated to form a heat influence area. And the structural change and the strength degradation in the heat affected zone greatly reduce the shaping and impact toughness of the part, and directly affect the fatigue performance and the safety of the part. In addition, the residual stress formed during the rapid cooling solidification of the metal material can cause the cracking of the cladding layer and the deformation of the part. Anisotropic coarse dendrites are formed in the deposited layer, which increases the brittleness of the cladding layer. Furthermore, the deposited layer has defects such as pores, lack of fusion and cracks, which are difficult to avoid. Due to the defects, the comprehensive mechanical property of the directional energy deposition forming part cannot reach the standard of a forged piece, and the popularization and the application of the directional energy deposition in more fields such as a long-term service established structural part are limited.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a steel part surface repairing method, which effectively reduces the defects of pores, unfused and cracks in a deposited metal structure by compounding directional energy deposition and rolling, refines grains, makes the structure more compact, and can control the stress distribution state of a cladding layer so as to improve the fatigue performance of the repaired steel part.

The invention adopts the following technical scheme:

the invention provides a steel part surface repairing method, which adopts a directional energy deposition and rolling composite mode, wherein the rolling temperature is controlled to be 800-1100 ℃, the rolling pressure is controlled to ensure that a deposition layer generates plastic deformation, the strain is 0.1-0.5, and the deformation rate is 0.1-1.2 s^-1And the rolling temperature is the surface temperature of the deposition area during rolling.

The local overheating and the rapid cooling of the metal material can generate large residual stress, so that the directional energy deposition mode still has certain defects on the surface repair quality. To overcome these defects, one possible method is to repair the surface defects or damaged areas of the part to their original form by directed energy deposition in conjunction with other processing means or external heat sources. In common repair mode combination, the laser impact technology has the defects of low repair efficiency and high cost; the depth of the ultrasonic impact technology is shallow, and the stress distribution of the deep layer in the part cannot be changed; hot isostatic pressing is expensive and layer-by-layer/interlayer pressurization is difficult to achieve. The inventors tried the combination of directed energy deposition and rolling, directed energy deposition and forging, etc., but the repair quality was still not ideal. The inventor innovatively combines directional energy deposition and rolling while depositing and rolling, and strictly controls the rolling temperature and pressure, so that defects such as air holes, unfused parts, cracks and the like in a deposited metal layer are reduced, grains are refined, the structure is more compact, and good mechanical properties and fatigue properties of a repaired part are realized.

In the repairing method, the directional energy deposition and the rolling are carried out simultaneously, namely, the rolling is carried out once the surface temperature of a deposition area formed by the directional energy deposition is reduced to a temperature range of 800-1100 ℃. Different from the existing steel part surface repairing technology in which the area to be repaired is completely deposited with metal and then is rolled or forged, the method can roll while depositing directional energy, and control the quality of the repairing layer by controlling the rolling temperature, strain and deformation rate, thereby achieving the required repairing effect.

The surface repairing method of the steel part can be used for the condition that the surface of the steel part is a plane, a cambered surface, a free-form surface and other surface contours.

In a preferred embodiment of the invention, the steel part surface repairing method comprises the following steps:

(1) machining the area to be repaired on the surface of the steel part to remove defects, damages and oxide layers;

(2) the high-energy beam processing head guides the high-energy beam to melt the area to be repaired on the surface of the steel part and the metal deposition material, and the high-energy beam processing head melts, solidifies and accumulates layer by layer according to a preset deposition track to form a deposition layer; the method comprises the steps of performing layer-by-layer or interlayer synchronous rolling during deposition, controlling the rolling temperature to be 800-1100 ℃ by adjusting the distance between a high-energy beam processing head and a roller, controlling the pressure of the roller to enable a deposition layer to generate plastic deformation under the action of pressure, wherein the strain is 0.1-0.5, and the deformation rate is 0.1-1.2 s^-1。

Further, in the step (2), the synchronous rolling comprises that the moving direction, the moving speed and the moving start-stop time are consistent, and after the rolling temperature is determined, the relative positions of the high-energy beam processing head and the roller are kept unchanged. The rolling temperature can be measured by a temperature sensor.

Further, in the step (2), the layer-by-layer or interlayer synchronous rolling means that the deposition layer is deposited layer-by-layer, and the rolling may be layer-by-layer rolling, i.e. depositing 1 layer and synchronously rolling 1 time, or interlayer rolling, i.e. synchronously rolling 1 time per deposition 2 layers or multiple layers. It is noted, however, that the thickness of the deposit between two rolls does not exceed 4 mm.

Further, in the step (2), the high-energy beam may be a high-energy heat source such as a laser, an arc, an electron beam, or a plasma beam.

Further, in the step (2), the metal deposition material is steel powder or wire material with the same or similar composition with the steel part material.

Further preferably, the rolling temperature is controlled to be 800-910 ℃, the strain of the deposited layer subjected to the pressure plastic deformation under the pressure action is 0.2-0.5, and the deformation rate is 0.2-1.0 s^-1。

The technological parameter window for rolling the steel parts mainly refers to the initial forging temperature and the final forging temperature in the steel forging technology, the minimum and maximum deformation, the dynamic recrystallization condition of the steel, the recrystallization degree, the optimal rolling temperature window of 800-910 ℃, the optimal strain interval of 0.2-0.5, 0.2-1.0 s and the like according to the moving speed of a high-energy beam processing head in the deposition process, the thickness of a deposition layer, the size of a roller and other conditions^-1The deformation rate interval of (1).

The invention also provides a steel part repaired by the steel part surface repairing method. Compared with the traditional repairing method, the obtained steel part repairing part has better tensile strength, yield strength, elongation and density, controls the residual stress generated by laser deposition high-temperature rapid cooling, and improves the mechanical property and the fatigue property.

The invention provides a steel part surface repairing method, which combines directional energy deposition and rolling, deposits metal in a repairing area and rolls simultaneously, namely, rolling is carried out after metal is completely deposited instead of normal operation, and the temperature and the pressure in the rolling process are regulated and controlled simultaneously, so that the defects of pores, unfused parts, cracks and the like in a deposited metal structure are effectively reduced, grains are refined, the structure is more compact, and the mechanical property and the fatigue property of a repairing part are obviously improved. The method has the advantages of simple equipment, low processing cost, high processing efficiency, no limitation of the size of parts, deep action depth and the like.

Drawings

FIG. 1 is a schematic view of a surface repairing method of a steel part by combining directional energy deposition and rolling in a powder feeding manner according to the present invention;

FIG. 2 is a schematic view of a wire feeding manner directional energy deposition and rolling combined steel part surface repairing method of the present invention;

in the figure: 1-steel parts to be repaired; 2-forming a cavity; 3-high energy beam processing head; 4-powder feeding device; 5-depositing a layer; 6-rolling; 7-a temperature sensor; 8-wire feeding device.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The embodiment provides a steel part surface repairing method, which comprises the following steps:

as shown in fig. 1, a steel part 1 to be repaired (which has been machined to remove defects, damages and oxide layers) is placed in a molding cavity 2 for fixation, and the molding cavity 2 is closed. And outputting laser by the high-energy beam processing head 3 to melt the surface of the steel part 1 to be repaired to form a molten pool, wherein the laser power is 1000W. The powder feeding device 4 simultaneously uses inert protective gas to convey metal powder into the molten pool, and the metal powder moves according to a planned path to form a deposition layer 5. Wherein the laser scanning speed is 13mm/s, the laser scanning interval is 0.3mm, the thickness of the single-layer deposition layer is 1.0mm, and 8 layers are co-deposited. The roller 6 and the high-energy beam processing head 3 synchronously move to perform interlayer rolling (once every two layers are deposited, when only the deposition is carried out but the rolling is not carried out, the roller 6 can be lifted to be not contacted with a deposition area), the surface temperature of the deposition layer 5 is measured by the temperature sensor 7, and the height is controlledThe distance between the beam processing head 3 and the roller 6 is controlled to enable the rolling temperature to be 860 ℃, the strain of the deposition layer 5 to be 0.4, and the deformation rate to be 1.0s^-1. The mechanical properties of the deposit 5 before and after rolling are shown in table 1.

Example 2

The embodiment provides a steel part surface repairing method, which comprises the following steps:

as shown in fig. 2, a steel part 1 to be repaired (machined to remove defects, damages and oxide layers) is placed in a molding cavity 2 for fixation, and the molding cavity 2 is closed. And outputting an electron beam by the high-energy beam processing head 3 to melt the surface of the steel part 1 to be repaired to form a molten pool, wherein the voltage of the electron beam is 25kV, and the current is 30 mA. The wire feeder 8 delivers the metal wire to the molten pool to move according to the planned path to form the deposition layer 5. Wherein the scanning speed is 3.5mm/s, the scanning distance of the electron beam is 25mm, the thickness of the single-layer deposition layer is 1.2mm, and 6 layers are co-deposited. The roller 6 and the high-energy beam processing head 3 synchronously move to roll layer by layer, the temperature sensor 7 is used for measuring the surface temperature of the deposition layer 5 and controlling the distance between the high-energy beam processing head 3 and the roller 6, so that the rolling temperature is controlled at 910 ℃, the strain of the deposition layer 5 is 0.5, and the deformation rate is 0.3s^-1. The mechanical properties of the deposit 5 before and after rolling are shown in table 1.

Example 3

The embodiment provides a steel part surface repairing method, which comprises the following steps:

as shown in fig. 2, a steel part 1 to be repaired (machined to remove defects, damages and oxide layers) is placed in a molding cavity 2 for fixation, and the molding cavity 2 is closed. And outputting electric arc through the high-energy beam processing head 3 to melt the surface of the steel part to be repaired to form a molten pool, wherein the electric arc voltage is 30V, and the current is 135A. The wire feeder 8 delivers the metal wire to the molten pool to move according to the planned path to form the deposition layer 5. Wherein the scanning speed is 4mm/s, the wire feeding speed is 70mm/s, and 9 layers are co-deposited. The roller 6 and the high-energy beam processing head 3 synchronously move to roll layer by layer, the temperature sensor 7 is used for measuring the surface temperature of the deposition layer 5 and controlling the distance between the high-energy beam processing head 6 and the roller 3, so that the rolling temperature is controlled at 850 ℃, the strain of the deposition layer 5 is 0.4, the deformation rate is 0Is 0.4s^-1. The mechanical properties of the deposit 5 before and after rolling are shown in table 1.

Comparative example 1

The comparative example provides a steel part surface repair method, which comprises the steps of machining an area to be repaired, removing defects, damages and an oxide layer, depositing metal through directional energy deposition (high-energy beam is laser), and finally rolling at room temperature. The mechanical properties of the deposit before and after rolling are shown in Table 1.

Comparative example 2

The comparative example provides a steel part surface repair method, which comprises the following steps:

and (3) placing the steel part to be repaired (which is subjected to machining treatment and has the defects, damages and oxide layers removed) into the forming cavity for fixing, and sealing the forming cavity. And outputting an electron beam by the high-energy beam processing head to melt the surface of the steel part to be repaired to form a molten pool, wherein the voltage of the electron beam is 25kV, and the current of the electron beam is 30 mA. The wire feeder conveys the metal wire to the molten pool, and the metal wire moves according to the planned path to form a deposition layer. Wherein the scanning speed is 3.5mm/s, the scanning distance of the electron beam is 25mm, the thickness of the single-layer deposition layer is 1.2mm, and 6 layers are co-deposited. The roller and the high-energy beam processing head synchronously move to roll layer by layer, the temperature of the surface of a deposition layer is measured by a temperature sensor, the distance between the high-energy beam processing head and the roller is controlled, the rolling temperature is controlled at 300 ℃, the strain of the deposition layer is 0.5, and the deformation rate is 0.3s^-1. The mechanical properties of the deposit before and after rolling are shown in Table 1.

The mechanical property test method of the deposition layer refers to the national standard GB/T: 228.1-2010.

TABLE 1 mechanical Property test results of repaired portions of examples and comparative examples

The results in table 1 show that the repairing method provided by the invention can effectively improve the mechanical properties of the repaired part.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.