A laser clad Co-based WC coating

A technology of laser cladding and cladding layer, which is applied in the direction of coating, metal material coating process, etc., and can solve problems such as thermal fatigue cracks, high temperature oxidation, high temperature wear, etc.

Inactive Publication Date: 2018-06-15
高扬
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

During use, because the hot forging die is subjected to repeated mechanical and thermal loads, the surface temperature of the mold cavity can reach above 500°C, and local failures

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment example 1

[0015] The raw materials for laser cladding Co-based WC coating include: the base material is H13 steel, the heat treatment state is forged, the sample size is 80mm×50mm×30mm, the H13 substrate surface is polished and cleaned with acetone before the experiment. The laser cladding materials are self-made Co-based alloy powder and WC powder, which are mechanically mixed at a ratio of 9:1. The particle size range of Co-based alloy powder is 45-109 μm, and the main elements are Co, C, Si, Cr, W, Mo, etc. The preparation steps of laser cladding Co-based WC coating are as follows: use LDF400-2000 fiber-coupled high-power semiconductor laser, its output wavelength is 900-1030nm, and the maximum output power is 2kW; the motion device uses IRB2400 / 16 six-degree-of-freedom robot; The powder feeding device adopts a coaxial powder feeding device with closed-loop feedback flow control. The optimized process parameters are: laser power density 5.10W / cm 2 , The scanning speed is 16mm / s, th...

Embodiment example 2

[0017] The cladding layer can be divided into cladding layer, heat-affected zone and substrate from top to bottom. Due to the extremely fast heating and cooling rates during the laser cladding process, the obtained cladding layer has no defects such as cracks, pores, inclusions and segregation, and is well bonded to the substrate. Near the bottom of the cladding layer, due to the large temperature gradient and low solidification rate, the bottom grows as planar crystals, followed by dendrites, which gradually develop into cellular crystals, and then near the upper part of the cladding layer, the temperature gradient approaches zero, and Affected by surface air convection cooling and other factors, the structure on the surface is more disordered, and the network structure is distributed around the columnar crystals. The phase composition of the cladding layer is solid solution Co, CoCx, Fe 3 W 3 C. (Cr, Fe) 23 C 6 Carbides, in which the dendrites are mainly composed of CoCx...

Embodiment example 3

[0019] The HDX-1000 digital microhardness tester is used to test the microhardness of the strengthened layer after laser cladding. The surface and the 1000μm area below belong to the laser strengthened area, and the highest hardness is reached at 900μm from the surface, which is mainly due to the WC. The mass density of the carbide hard phase generated by adding is greater than that of the relatively soft Co solid solution, so the carbide sinks to the bottom, so the highest hardness of the cladding layer is not on the surface of the cladding layer. The highest hardness of the cladding layer reaches 520HV 0.2 , the average hardness of the cladding layer reaches 430HV 0.2 , while the matrix hardness is 250HV 0.2 The hardness of the cladding layer is increased by about 2 times. This is mainly due to the formation of CoCx, Fe 3 W 3 C. (Cr, Fe) 23 C 6 The hard phase is dispersed in the coating, which plays a role of dispersion strengthening; in addition, the process of rapid ...

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Abstract

A laser clad Co-based WC coating is disclosed. Co-based WC composite powder is subjected to laser cladding on a surface by adopting a semiconductor laser. The microhardness and high-temperature wear resistance of the coating after laser cladding are improved to a large extent. The major constitution phases of the coating are a supersaturated solid solution Co, and hard phases including CoCx, Fe<3>W3C, (Cr,Fe)<23>C6, and the like. In a wear process of the coating at a high temperature of 600 DEG C, on the one hand, a Co-rich area which is relatively low in hardness is worn firstly so that carbide hard phases having high hardness are shown on the surface and wearing action of a material is prevented; and on the other hand, Co and Cr elements promote formation of CoO and CoO.Cr2O3 oxide filmshaving lubricating functions in a high-temperature friction process so that the friction coefficient is reduced, and therefore high-temperature wear resistance of the clad layer is increased by about2 times. High-temperature wear mechanisms of the clad layer mainly include abrasive particle wear and adhesive wear.

Description

Technical field [0001] The invention relates to a surface coating material, in particular to a laser cladding Co-based WC coating. Background technique [0002] Hot forging die is an important metal forming tool, which is widely used in machinery, automobile and other fields. During use, because the hot forging die is subjected to repeated mechanical and thermal loads, the surface temperature of the mold cavity can reach above 500°C, and local failures such as thermal fatigue cracks, high-temperature oxidation, and high-temperature wear are prone to occur, and local failures often lead to overall failure. The scrapping of the mold. High-temperature wear is an important failure mode of hot forging dies, and improving the high-temperature wear performance of dies is the key to increasing their service life. [0003] As an advanced surface engineering technology, laser surface strengthening technology has been widely used in surface strengthening and remanufacturing in recent...

Claims

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Application Information

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IPC IPC(8): C23C24/10C22C19/07C22C32/00
CPCC23C24/103C22C19/07C22C32/0052
Inventor 高扬
Owner 高扬
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