First, diffusion metal carbide coating technology introduced
1. Technical Introduction
Diffusion method metal carbide coating technology is to place the workpiece in a special medium, the diffusion effect on the surface of the workpiece to form a layer of several microns to tens of microns of metal carbide layer. The carbide layer has a very high hardness, HV up to 1600 ~ 3000 (determined by the type of carbide), in addition, the carbide substrate and the metallurgical bonding, does not affect the surface finish of the workpiece, has a very high wear resistance, resistance Occlusion (cohesion), corrosion resistance and other properties, can greatly improve the service life of tooling and mechanical parts.
2. Comparison with related technologies
The method of forming a super-hard compound film layer on the surface of a workpiece is an effective and economical method that greatly improves its wear resistance, seizure resistance (anti-sticking), corrosion resistance, and the like, thereby greatly improving its service life. At present, the methods for super-hardening the workpiece surface mainly include physical vapor deposition (PVD), chemical vapor deposition (CVD), physical chemical vapor deposition (PCVD), and diffusion metal carbide substrate technology, wherein the PVD method has a low deposition temperature. The small deformation of the workpiece, but due to the poor adhesion of the film layer and the substrate, the process of coating around the poor, it is often difficult to play the performance advantages of super-hard film. The CVD method has outstanding advantages such as good bonding strength of the film base and good process reflowability, but for a large number of steel materials, the subsequent matrix hardening treatment is troublesome, and the film layer is easily damaged. Therefore, its application is mainly focused on hard alloys and other materials. The PCVD deposition temperature is low, and the film base bond strength and process reflowability are significantly improved compared to the PVD method. However, compared with the diffusion method, there is still a large gap between the film-based bonding force and the plasma film formation due to the PCVD method. Although coiling is improved compared to PVD, it cannot be eliminated.
The metal carbide coating formed by the diffusion metal carbide coating technology forms a metallurgical bond with the substrate, and has a comparable film-based bonding force with PVD and PCVD. Therefore, this technology can really exert the performance advantages of the superhard film layer. This technology does not have the problem of coating around, the subsequent substrate hardening treatment is convenient, and can be repeated for many times, so that the application of this technology is more extensive.
3, technical advantages
Diffusion metal carbide coating technology is widely used in Japan, European countries, Australia, South Korea and other countries. According to investigations, a large number of matching dies on imported equipment have used this technology in large quantities. When these molds are made in China, due to the lack of corresponding mature technologies, the dies often have low service life, and some of them cannot even be made locally.
This technique was studied in the 1970s, but due to the limitations of various conditions, it is often difficult for the process and equipment to pass the test of batch and long-term production, so that some of the actual problems in the technology are not easy to expose or difficult to solve, and are often abandoned halfway. . During more than ten years of research and application, we have conducted in-depth research on the actual problems in the technology and equipment of the technology, and made effective improvements. The improved technology and complete sets of equipment have been able to meet the long-term needs. The requirements for stable production, the level of mold life handled by the mold have reached the level of the life of similar imported molds, and a wealth of practical experience in the production of various types of molds has been achieved, laying a solid technical foundation for the large-scale application of this technology.
4, the scope of application
Diffusion metal carbide coating technology can be widely used in various types of tooling or mechanical parts due to wear and bite failure. Among them, the failure due to wear (such as punching, cold heading, powder molding, etc.) can increase the life time from several times to several ten times; the problem of the product or die pulling caused by the bite (such as the extension die, flanging) Models, etc.) can be fundamentally resolved.
Applicable materials: die steel, structural steel with carbon content greater than 0.3%, cast iron, hard alloy.
Second, stainless steel pipe mold surface super-hardening treatment technology
The stainless steel welded pipe is formed on the welded pipe forming machine. The stainless steel plate is rolled and formed by several molds and welded. Due to the high strength of stainless steel, and its structure of face-centered cubic lattice, easy to form work hardening, so that when the pipe is formed: on the one hand the mold to withstand greater friction, so that the mold is easy to wear; on the other hand, stainless steel sheet It is easy to form a bond (occlusion) with the surface of the mold, causing a strain on the surface of the pipe and the mold. Therefore, a good stainless steel mold must have extremely high wear resistance and anti-adhesion (biting) properties. Our analysis of imported welded pipe moulds shows that the surface treatment of this type of moulds is treated with superhard metal carbide or nitride coatings.
Stainless steel pipe forming mold materials are generally made of high carbon and high chromium Cr12MoV (or SRD11, D2, DC53). At present, the following processes are commonly used to make molds: cutting, roughing, heat treatment (high-temperature quenching and high-temperature tempering), finishing, nitriding, and finished products (Note: In order to save costs, manufacturers generally eliminate the need for forging. Ball annealing two time-consuming, financial process). Since the Cr12MoV material is a high-carbon, high-chromium alloy steel, there is a large segregation in the original structure (this segregation cannot be eliminated even with ordinary forging). After the heat treatment (high quenching and high recovery), the internal structure of the mold is extremely uneven, and the macroscopic appearance is that the hardness is extremely uneven (HRC is about 40 to 60), and after nitriding, the surface unevenness of the mold cannot be eliminated. The hardness is even further reduced. In actual use, it shows that the surface of the die and the welded pipe is easily damaged, and the die life is low.
The super-hardened surface treatment technology of mold surface researched by Hunan Tepu Electronic Co., Ltd. has been successfully applied to stainless steel welded pipe forming dies. The molds treated by this technology form a metal carbide layer with a hardness as high as about HV3000 on the surface. The carbide layer is dense and tightly bonded to the substrate, does not affect the surface finish of the workpiece, and has extremely high wear resistance and seizure resistance. Fundamentally solve the problem of brazing of the welded pipe, reduce the workload of the subsequent polishing process of the pipe making and improve the product quality, greatly increase the service life of the mold, and reduce the after-sales service workload. Practice shows that this technology has a very high use value. The following is a comparison of the process mold and nitride mold.
1, performance:
Nitriding die This process handles the die surface hardness: about HV700~1000 HV3000 about the substrate hardness: extremely uneven HRC58~62
HRC40~60
2, process flow:
Nitriding mold: cutting → roughing → heat treatment (high quenching high back) → finishing → nitriding → finished product
The process of processing the mold: cutting → all processing in place (without heat treatment) → the process (base hardening and surface treatment once completed). → grinding inner hole → finished product can be seen from the process, using this process can shorten the mold processing cycle.
3, the use of effects:
The mold processed by this process can fundamentally solve the pulling of the welded pipe compared with the nitrided mold, thereby reducing the workload of the subsequent polishing process of the welded pipe and improving the product quality (because a large amount of polishing reduces the wall of the pipe), and the service life of the mold is greatly improved. Reduce after-sales service workload.
The ultra-hardened surface treatment technology developed by Hunan Tepu Electronics Co., Ltd. has been widely used in actual production and has been well received by customers. Therefore, the life of the die processed by this process is greater than that of traditional processes such as nitriding. Improve, in some mold performance than foreign standards, and the price is only 1/4 to 1/10 of the same foreign.
The mold processed by this process has rolls, punches, color tube series cold working molds, standard parts molds, pyrophyllite molds, copper aluminum extrusion molds, etc., enabling customers to have a very high efficiency, so that the mold's cost performance Quality improvement