Hard alloy large pipe drawing mold and preparation method

Abstract

The invention provides a hard alloy large pipe drawing mold and a preparation method. The hard alloy large pipe drawing mold comprises the following raw material ingredients in percentage by weight: 14 to 20 percent of cobalt with a particle size of 1.0 to 3.0mu m, and the balance of tungsten carbide with a particle size of 4 to 5mu m. The preparation method comprises: raw material preparation, wet milling, drying, pressing, forming agent removal and sintering, wherein in the drying step, wax or butadiene rubber is used as the forming agent; the drying with the wax as the forming agent is spray drying; the forming agent remove is performed in a dewaxing and sintering integrated furnace or bell-type furnace; and the sintering is pressure sintering, and during the sintering, the temperature is raised within 11 to 13 hours till a liquid phase of the product appears, then about 40 mbars of high-purity argon is introduced into the furnace till the final sintering temperature of 1,390 to 1,400 DEG C, the temperature is kept for 50 to 60 minutes, then about 50 to 60 bars of high-purity argon is introduced, the temperature is kept continuously for 50 to 60 minutes, and the product is cooled to room temperature. The Rockwell hardness of the hard alloy large pipe drawing mold of the invention is more than or equal to 83HRA, the bending strength of the hard alloy large pipe drawing mold is more than or equal to 2,200MPa, and the density of the hard alloy large pipe drawing mold is 13.40 to 14.20g / cm<3>. And the hard alloy large pipe drawing mold has the advantages of high hardness, high wear resistance, uniform product performance, fragmentation resistance and long service life.

Description

technical field [0001] The invention relates to a large hard alloy pipe drawing die and a preparation method thereof, especially a large hard alloy pipe drawing die with an outer diameter of 300mm or more and a preparation method thereof. Background technique [0002] With the increasing demand for large-size and high-quality seamless steel pipes, the demand for molds required for seamless steel pipe production is very urgent. Due to the high requirements on the wear resistance and strength of the molds, Cr12MoV steel has been used for boronizing treatment or No. 45 steel has been processed After compound heat treatment, the surface hardness is increased to meet the requirements of use, but because the wear resistance does not meet the requirements, frequent replacement is required, and cemented carbide molds are gradually used. In the production of cemented carbide molds in China, the cobalt content is generally 8% to 11%, and only small-sized pipe drawing dies (outer diame...

AI Technical Summary

Problems solved by technology

In the production of cemented carbide molds in China, the cobalt content is generally 8% to 11%, and only small-sized pipe drawing dies (outer diameter ≤ 300mm) can be produced, and there are still many problems, the main problem is wear resistance Insufficient, poor uniformity of product performance, easy to break, low pass rate, short service life, general drawing capacity is less than 1000 tons

Chinese patent "large-diameter hard alloy metal pipe drawing die and its manufacturing method" (200810023793.3), which can produce large-diameter hard alloy pipe drawing die with an outer diameter ≥ 500mm, the selected cobalt content is 17.5-18.5%, and the tungsten carbide is 1.2-2.0μm, using styrene-butadiene rubber as a molding agent, degumming to 800°C after 15-16 hours, heating to 1430-1440°C in 8-9 hours and holding for 40-50 minutes to complete sintering. The strength is low, and the quality control of the production process is difficult; the sintering and heat preservation time is short, and it is difficult to ensure the consistency of the performance of the surface layer and the core of the product.

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