1.diffusion metal carbide coating technology introduction
Diffusion method of metal carbide coating technology is the workpiece is placed in the special medium, by diffusion to the surface to form a layer of a metal carbide layer microns to tens of microns. The carbide layer has high hardness, HV can reach 1600~3000, in addition, the carbide coatings metallurgically bonded to the substrate with, does not affect the work piece surface finish, high wear-resistant, anti seizure, corrosion resistance, can greatly improve the tooling and machinery parts of life.
Through the method of super hard compound film formed on the surface of the workpiece, is greatly improved the wear, scuffing, corrosion resistance, and thus greatly improve the service life of the effective and economic method. At present, the workpiece surface hardening treatment methods mainly include physical vapor deposition, chemical vapor deposition, physical and chemical vapor deposition, diffusion method of metal carbide coating technology, in which, the PVD method has low deposition temperature, the deformation of the workpiece is low, but because the coating and substrate binding ability is poor, not around the plating process well, are often difficult to play the advantages of ultra hard compound film. The CVD method has good adhesion, craft circle plating to highlight the advantages of good, but for a large amount of steel materials, the matrix hardening treatment is difficult, somewhat careless, film can easily destroy. So its application is mainly concentrated in the hard alloy material. PCVD low deposition temperature, film substrate adhesion and process circle plating than PVD method has greatly improved, but compared with diffusion method, binding force is still a big gap, because PCVD method is still the plasma membrane, although around plating than PVD method has been improved, but cannot eliminate.
The diffusion of metal carbide coating method of metal carbide coating technology was formed, the metallurgical bonding with the substrate, the film substrate is unable to compare with PVD, PCVD together, so this technique can really play a performance advantage, super hard layer in addition, the technology does not exist around the plating issues, subsequent matrix hardening treatment is convenient, and can be repeated many times, the applicability of this technique is more extensive.
Diffusion method of metal carbide coating technology widely in Japan, Europe, Australia, South Korea and other countries the application. According to the survey, many imported equipment supporting the mold on the massive use of this technology, the mold in domestic production, due to the lack of corresponding mature technology, tends to make the die life is low, some can't even localization.
The technology of domestic seventy's was studied, but due to various constraints, technology and equipment are often difficult to batch and long-term production test, so that some of the technology in practical problems is not easy to expose or difficult to solve, often give up halfway. We are in the process of research and application of 10 years of in the process, equipment, the practical problems of the existing in the research, and the effective improvement, the improved technology and complete sets of equipment have been able to meet the long-term stable production requirements, service life of the die level reaches the same level of mold processing life, yielded a wealth of practical application experience in the production of various types of mold, has laid a solid technical foundation for large-scale popularization and application of the technology.
Diffusion of metal carbide coating technology can be widely applied to various due to wear, occlusion caused by failure of the tooling or machinery parts. Among them, because of wear caused by the failure of service life can be improved by several times to several times; due to occlusion caused by the products or moulds strain problem, can be solved fundamentally.
Die steel, structural steel, carbon content of more than 0.3% cast iron, hard alloy.
2.Processing technology of stainless steel welded pipe two, die surface hardening
Stainless steel welded pipe is in welded pipe forming machine, made of stainless steel plate after rolling and forming die if road and welded together by the. Due to the high strength stainless steel, and the structure of the face centered cubic lattice, easy to form the work hardening, the welded pipe forming die: a bear greater friction, the mould is easy to wear; on the other hand, easy to form a bond with the mold surface of stainless steel sheet, so that the formation of a welded pipe and the mold surface. Therefore, stainless steel mold good must have high abrasion resistance and anti adhesive properties. Our analysis of the inlet pipe mould show that, surface treatment of the dies are used in super hard metal carbide or nitride coating process.
Stainless steel welded pipe forming mould material is generally made of Cr12MoV high carbon high chromium. Currently widely used the following process production mold: blanking, rough machining, heat treatment, machining, nitriding and product (Note: in order to save costs, general manufacturers now have saved the forging and annealing of two time, fee property procedure). Because the Cr12MoV class material belongs to high carbon high chromium alloy steel, there are a lot of composition segregation of their original tissue. So after heat treatment of die internal organization is very uneven, the macro performance of hardness is very uneven, and the nitriding process, the mold surface heterogeneity can not be eliminated, matrix hardness even further reduced, the actual use, the performance of the surface of mold and welded pipe are easy to strain, the mold life.
After the technical treatment on its surface to form a metal carbide layer hardness up to hv3000 or so, the carbide layer of dense, tightly combined with the matrix, does not affect the surface finish of the workpiece, high abrasion resistance, anti seizure properties, can solve the problem of pipe pulling hair from the root, reducing pipe making subsequent polishing process workload and improve product quality, improve the service life of the die, reduces the workload of after sale service. Practice shows that, this technology has high value in use. The following is the process of die and mould compared with nitriding.
The process of die mold nitride
Surface hardness: hv700~1000 hv3000
The uneven hardness: hrc58~62
Nitriding mould: blanking, rough machining, heat treatment, machining, nitriding and product
The process of mold: blanking, all processing in place, this process. And grinding inside holes and product
The process can be seen, the technique can shorten the processing cycle of die.
Die this process is nitrided die can fundamentally solve the pipe galling, thereby reducing pipe subsequent polishing workload and improve the product quality, greatly improve the service life of the die, reduces the workload of after sale service.
After this process with a roll, punch, die of cold color series, standard mold, pyrophyllite mold, aluminum profile extrusion die, so that customers have a high efficiency, to mold the price of quality improvement.