Sintering technology for cemented carbide extrusion bar

Abstract

The invention discloses a sintering technology for a cemented carbide extrusion bar. The sintering technology comprises four continuous processes of positive-pressure hydrogen dewaxing, partial-pressure sintering, high-pressure and high-temperature sintering, and cooling. At a normal temperature, hydrogen is filled into an empty sintering furnace, the furnace temperature is gradually boosted to 600 DEG C stage by stage in 490 minutes, the hydrogen is cut off, a mechanical pump is used for controlling the vacuum degree in the furnace to be about 10 pascals of the inner pressure of a sintering box, argon is then filled into the sintering box so as to ensure that the inner pressure of the sintering box is between 300 and 600 pascals, the furnace temperature is gradually increased to 1410 DEG C in 235 minutes stage by stage under the pressure of 300-600 pascals, the furnace is kept at the temperature of 1410 DEG C for 60 minutes, high-pressure argon of 60 bars is filled into the furnace for 20 minutes after the thermal insulation at 1410 DEG C is maintained for 30 minutes, the high pressure of the argon is maintained for 10 minutes, the pressure maintaining and temperature maintaining are finished at the same time, and then, the furnace begins to be cooled. Under the condition of fully filling the high-pressure argon in the furnace, the furnace is naturally cooled to 900 DEG C and is then quickly cooled to below 50 DEG C after about 300 minutes. The sintering technology can be used for effectively improving the bending percent of pass of the thin cemented carbide extrusion bars with the diameter of no more than phi 6 millimeters.

Description

technical field [0001] The invention relates to a sintering process of hard alloy extruded rods, which can improve the bending pass rate of hard alloy extruded rods, especially can improve the first-time pass inspection rate of small-diameter hard alloy extruded rods. Background technique [0002] In the case of diameter D≤Ф6mm, the sintering of cemented carbide extruded rods usually has a low first pass rate of straightness. The molding agents of cemented carbide extruded rods mainly include paraffin, cellulose, etc., and the molding agents can be completely removed in hydrogen positive pressure dewaxing. However, in the subsequent vacuum sintering and pressure sintering, there are more or less bending phenomena, and the proportion of thin-diameter extruded alloy rods is the largest. In the pressure sintering furnace, the problem of sintering bending is particularly prominent. This is because, in the current common alloy sintering process, after the molding agent is remove...

AI Technical Summary

Problems solved by technology

However, in the subsequent vacuum sintering and pressure sintering, there are more or less bending phenomena, and the proportion of thin-diameter extruded alloy rods is the largest. In the pressure sintering furnace, the problem of sintering bending is also particularly prominent.

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