Stainless steel welded pipe die materials are generally made of high carbon and high chromium Cr12MoV(or SRD11,D2,DC53). The following process is generally used to make the mold: blanking; Rough machining; Heat treatment (high-temperature quenching and tempering); Finishing; Nitride; Finished products (note: in order to save costs, general manufacturers have now eliminated the two time-consuming and costly processes of forging and spheroidizing annealing). As Cr12MoV materials belong to high carbon and high chromium alloy steels, there is a large component segregation in the original microstructure (such segregation cannot be eliminated even by ordinary forging). After heat treatment (quenching back) uneven mold internal organization, macroscopic performance for its uneven hardness (HRC 40 to 60 or so), then through nitriding processing, mold surface irregularity cannot eliminate, hardness even further reduce the matrix, and the actual use, all easy appearance to the mold and welded pipe strain, die life is low.
Stainless steel molding dies must have extremely high wear and adhesion (bite) resistance. Stainless steel welded pipe is made of stainless steel plate by a number of die rolling molding and welding on the welding pipe forming machine. Because the strength of stainless steel is high, and its structure is face-centered cubic lattice, easy to form work hardening, so that the welded pipe forming: on the one hand, the mold should bear greater friction, so that the mold is easy to wear; On the other hand, the stainless steel sheet is easy to form a bond with the surface of the mold (bite), so that the welded pipe and the surface of the mold form a strain. Our analysis of imported welded pipe moulds shows that the surface treatment of these moulds is superhard metal carbide or nitride coating.
Compared with nitriding mould, the mould processed by this process can fundamentally solve the flapping of welded pipe, thus reducing the workload of subsequent polishing process of welded pipe and improving product quality (the tube wall is reduced due to a large amount of polishing), greatly improving the service life of the mould and reducing the workload of after-sales service.
The die surface superhardening treatment technology has been widely used in the actual production, the life of the die treated by this process is greatly improved compared with the traditional process such as nitriding, and the performance of some dies exceeds the foreign level, while the price is only 1/4~1/10 of the same abroad. The moulds processed by this process include roller, punch, color tube series cold making moulds, standard parts moulds, pyrophyllite moulds, copper-aluminum extruding moulds, etc., so that customers have a high benefit, so that the cost performance of moulds has been improved.
