Heat treatment process of carbide alloy for cold heading dies

Abstract

The invention discloses a heat treatment process of a carbide alloy for cold heading dies, which comprises the following steps: (1) putting the sintered carbide alloy for cold heading dies into a heating chamber of a double-chamber vacuum furnace, and vacuumizing the heating chamber until the pressure of the heating chamber is (2*10-1)-(4*10-1) Pa; (2) heating the heating chamber in two stages, in the first phase, heating the heating chamber to 900 DEG C at a speed of 5-8 DEG C / min, and then carrying out heat preservation for 30-45 minutes, and in the second stage, heating the heating chamber to 1100-1300 DEG C at a speed of 8-10 DEG C / min. and then carrying out heat preservation 30-40 minutes; (3) filling high-purity nitrogen gas as shielding gas in the furnace, under the condition that the vacuum degree is 0.5-0.8 bar, completely soaking a heated product into a cold-chamber oil-quenching bath for 4-6 minutes, then ascending and separating the obtained product, and cooling the obtained product to below 60 DEG C; and (4) putting the obtained product into a vacuum tempering furnace to carry out tempering treatment for 5-6 hours at a tempering temperature of 450-600 DEG C, carrying out furnace cooling on the obtained product until the obtained product is at room temperature, and taking out the obtained product. According to the invention, the content of a face-centred cubic structure alpha-Co in the alloy is increased, the toughness and the strength are improved, the comprehensive mechanical properties are good, phenomena such as fatigue cracking, breakage and early wear in the process of application are reduced, and the purposes of prolonging the service life, reducing the application cost and increasing the application efficiency are achieved.

Description

[0001] technical field [0002] The invention relates to a processing method of cemented carbide, in particular to a heat treatment process of cemented carbide for cold heading dies. Background technique [0003] Compared with traditional alloy tool steel dies, cemented carbide cold heading dies have a service life of more than ten or even dozens of times. At present, they have been widely used in the production of standard parts in my country, and their demand is increasing day by day. Commonly used cemented carbide materials for cold heading dies are generally tungsten-cobalt cemented carbides. The wear resistance, toughness, and bending strength of such cemented carbides depend to a large extent on the cobalt phase in the alloy. form. For alloys with the same composition, when the α-Co content of the face-centered cubic structure in the cobalt phase is more, the cobalt phase can absorb more strain energy and relax stress, better coordinate the two-phase strain state, and...

AI Technical Summary

Problems solved by technology

For alloys with the same composition, when the α-Co content of the face-centered cubic structure in the cobalt phase is more, the cobalt phase can absorb more strain energy and relax stress, better coordinate the two-phase strain state, and the alloy has good toughness and resistance to stress. The bending strength is high; when the ε-Co content of the close-packed hexagonal structure is high, the ability of the cobalt phase to absorb strain energy and relaxation stress and coordinate the strain state of the two phases is poor, the alloy has poor toughness and low bending strength

At present, the cemented carbide cold heading die parts produced by the traditional process are generally high-cobalt alloys with a cobalt content of 20%~30%, a hardness of HRA81~83, and a bending strength of 2000~2800MPa. Co accounts for about 100%, and there is no α-Co. Although this type of alloy has excellent properties of high hardness and high wear resistance, it has low bending strength and poor toughness, and is prone to problems such as fatigue cracking and chipping. performance drop

"Vacuum Heat Treatment Method for Low-Cobalt Cemented Carbide Rods" (CN200710049120.0) and "Vacuum Heat Treatment Method for Cemented Carbide for Drilling and Rock Drilling" (CN200610020648.0) proposed to use vacuum heat treatment process to improve the α- Although the method of Co content can achieve the purpose of improving the comprehensive mechanical properties of the alloy, it is all aimed at low-cobalt and medium-cobalt cemented carbide, and its process method is not suitable for heat treatment of high-cobalt cemented carbide for cold heading dies.