Metal surface mechanically-assisted electric heat alloying preparation method

Abstract

The invention relates to a metal surface mechanically-assisted electric heat alloying preparation method. The method comprises the first step of pretreatment of a base body of a metal workpiece to be alloyed, the second step of electric heat alloying electrode preparation, the third step of electric heat alloying equipment assembly, the fourth step of electric heat alloying preparation and the fifth step of grinding and polishing of the base body of the alloyed metal workpiece. The preparation method has the advantages that the prepared alloyed layer is compact and uniform, no brittle ceramic, nitride, oxide or other matter is formed, the alloyed layer is in metallurgical bonding with the base body, no obvious interface is formed, and a strengthened layer is high in quality; the alloy element selection range is wide, the metal wire bundle machining technological difficulty is low, and the cost is lower; no special requirement exits for the workpiece shape and precision, and applicability is high; operation is simple and easy to implement, machining efficiency is high, and surface hardening treatment can be achieved for large-area complex workpieces; equipment is simple, one-time investment is low, the maintenance cost is low, and the machining cost is low.

Description

technical field [0001] The invention relates to the technical field of surface treatment, in particular to a preparation method for mechanically assisted electrothermal alloying of metal surfaces. Background technique [0002] The main causes of failure of metal parts are fatigue (61%), overload (18%), stress corrosion (8%), excessive wear (7%), corrosion (3%), high temperature oxidation (2%) %), stress failure (accounting for 1%); except for overload, other failures are related to the surface state of parts; therefore, most metal parts need surface strengthening treatment in actual use. [0003] Traditional surface strengthening techniques can be divided into two categories: surface coating and surface modification. [0004] Surface coating treatment includes electroplating, electroless plating, spraying, vapor deposition, oxidation and other methods. There are large differences between the composition, structure, density and mechanical properties of the coating material a...

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Problems solved by technology

[0009] The high-energy beam surface alloying process has high processing costs (low energy utilization rate), high equipment and maintenance costs, and quality defects such as microcracks

[0010] The micro-arc spark deposition technology deposits the electrode material on the surface of the metal substrate through the pulse discharge of the capacitor, so that the substrate and the electrode material undergo a metallurgical reaction to form a high-hardness surface-enhanced alloyed coating, thereby improving the wear resistance and corrosion resistance of the titanium surface. However, the slow speed and low efficiency of micro-arc spark deposition make this technology only suitable for micro-repair of surface weight loss defects of precision parts, not suitable for repairing thicker coatings (coating thickness > 0.25mm), and even less suitable for smaller Large-area processing; and the entire processing process needs to go through processes such as machining, surfacing welding thickening repair, grinding and leveling; therefore, the application field of micro-arc spark deposition technology is very limited

[0011] Documents "Synthesis of TiN Coatings by EDM on Flexible Titanium Electrodes" and "Research on EDM Strengthening Experiments on Surfaces of Flexible Electrodes on Titanium Alloys" published a flexible EDM deposition method; The speed and quality control have been improved, but the defects of this process are more obvious: (1) The process does not solve the shortcomings of slow EDM deposition speed and low efficiency; (2) The electrode size becomes larger, resulting in increased difficulty in on-site or manual operation ; (3) In order to obtain a more sufficient spark discharge effect and stability, it is necessary to ensure that the wire bundle density in the circular wire reel is low and the gap between the single electrode wire and the substrate is controlled within a reasonable range, and the strengthening layer Obtained entirely by electrode deposition, resulting in large consumption of monofilaments and large changes in the size of the wire disc during processing, resulting in poor process stability and inability to perform long-term and large-area processing; among them, the document "Synthesis of TiN Coatings by EDM with Flexible Titanium Electrodes "The selection of wire-shaped electrode materials that react with nitrogen gas is limited, and the formed TiN is a ceramic material, which is brittle and has a smaller scope of application. The high-energy discharge action of the molten metal surface reacts violently with the air to form oxides and there are a large number of granular electrode material impurities, the coating uniformity is poor, the density is low, the brittleness is large, and the surface roughness is difficult to control

[0012] Chinese patent announcement number CN 101817159 A discloses "a method of EDM grinding and polishing the surface of flexible electrode parts, which is characterized in that: the speed-regulating motor drives the conductive flexible electrode to rotate, and the flexible electrode and the surface of the part as the other pole are connected Pulse power supply / direct current, driven by the stepping motor on the insulating workbench, the flexible electrode approaches the surface of the part, and when it reaches the discharge gap, spark discharge is generated, and the polishing medium is sprayed into the discharge area or the discharge area is invaded by the polishing medium, and the spark discharge is used Energy, etch away the surface material of the protruding part of the surface of the part, while the rotating flexible electrode has a mechanical grinding effect on the surface of the part, and the rotating flexible electrode drives the polishing medium to polish the surface of the part”; this process is different from the traditional EDM The principle of cutting and polishing is the same, that is, the protrusions on the surface of the workpiece are removed by capacitive pulse discharge to achieve the purpose of polishing, and the requirements for the accuracy of the workpiece are reduced; similarly, it is necessary to ensure that there is a suitable gap between the brush and the workpiece during the process of this process. The discharge gap, so the mechanical grinding effect of the brush can be ignored; on the contrary, due to the strong stirring of the flexible electrode to the liquid and the huge resistance caused by it, higher requirements are put forward for the protection and processing of the equipment; on the other hand, Although this process avoids the violent reaction between the melt and the medium in the above-mentioned literature through the protection of the polishing medium, it also loses the strengthening effect of the electric spark; therefore, this process is only suitable for the deburring of some small and fine parts, and it is difficult The disadvantages of this process become very obvious when it is widely used, especially when dealing with large parts, large area processing or when a good strengthening effect is required

[0013] The document "Surface aluminizing on Ti-6Al-4V alloy via a novel multi-pass friction-stir lap welding method: Preparation process, oxidation behavior and interlayer evolution" discloses a multi-pass friction stir welding lap welding solid-state processing technology, which also exists Obvious shortcomings: (1) It is only suitable for strengthening treatment of a specific flat surface, and does not have the actual large-scale application conditions; (2) It requires special friction welding and tooling fixtures, and subsequent turning and milling processing is required, the process is complicated and the cost is high; ( 3) It is only suitable for scientific research and can hardly be used for surface strengthening treatment of finished parts

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