CN-121042538-B - Metal powder metallurgy forming process

Abstract

The invention discloses a metal powder metallurgy forming process, and belongs to the technical field of metal powder metallurgy. The process includes compounding metal mixture containing tungsten, copper, nickel, iron and interface toughening agent in certain proportion, adding water solution of PVA, stirring, molding to form green compact, pre-sintering, cooling and other steps to obtain sintered compact, and final shaping to obtain the final product. Compared with the prior art, the invention obviously improves the fracture toughness and the extensibility of the material, brings innovative breakthrough for the metal powder metallurgy forming process, and can be widely applied to the requirements of the fields of aerospace, automobile manufacturing and the like on high-performance metal parts.

Inventors

• HU WENWU
• CHEN JIANSHUI
• HU CHANGFU
• HUANG JIANFANG

Assignees

• 浙江衢州永丰金属制品有限公司

Dates

Publication Date

20260505

Application Date

20250901

Claims (7)

1. 1. A metal powder metallurgy forming process, comprising the steps of: Step 1, metal powder material proportion, namely weighing tungsten, copper, nickel, iron and an interface toughening agent according to proportion, fully and uniformly mixing to obtain a metal mixture; step2, mould pressing, namely filling the mixture into a mould cavity, and performing mould pressing forming to obtain a green body; Step 3, sintering at high temperature, namely heating up to 350-450 ℃ at a heating rate of 1-5 ℃ per minute in a presintering section, preserving heat for 20-30min, continuously introducing hydrogen, preserving heat for 20-40min at a temperature of 1400-1600 ℃ in a sintering section, continuously introducing mixed gas, controlling the cooling temperature to be lower than 150 ℃ in a cooling section, and continuously introducing nitrogen in the cooling process to obtain a sintered blank; Step 4, shaping, namely putting the sintered blank into a shaping die, applying cold pressing pressure, and performing secondary shaping when the dimension out-of-tolerance is more than 0.1mm to obtain a shaped alloy material; The interface toughening agent is composed of tungsten-chromium alloy powder and yttrium powder in a mass ratio of (1-3) 1; The weight ratio of each substance in the metal mixture is 2-6% of copper, 1-5% of nickel, 1-5% of iron, 1-5% of interface toughening agent and the balance of tungsten.
2. 2. The molding process according to claim 1, wherein the amount of the aqueous solution of polyvinyl alcohol added is 5-15% by weight of the total mass of the metal mixture, and the concentration of the aqueous solution of polyvinyl alcohol is 5-20% by weight.
3. 3. The molding process according to claim 1, wherein the unit pressing pressure of the compression molding in the step 2 is 0.5 to 1T/cm 2 , and the pressure is maintained for 10 to 20 seconds after the compression.
4. 4. The molding process according to claim 1, wherein the flow rate of the hydrogen continuously introduced into the pre-sintering section in the step 3 is 5-10L/min.
5. 5. The molding process according to claim 1, wherein the mixture gas continuously introduced into the sintering section in the step 3 is hydrogen and nitrogen in a volume ratio of 5-9:2-4, and the flow is 5-10L/min.
6. 6. The molding process according to claim 1, wherein the cooling section in step 3 is continuously fed with nitrogen at a flow rate of 2 to 6L/min.
7. 7. The molding process of claim 1, wherein the cold pressing pressure in step 4 is 0.4-0.8T/cm 2 .

Description

Metal powder metallurgy forming process Technical Field The invention relates to the technical field of metal powder metallurgy, in particular to a metal powder metallurgy forming process. Background The metal powder metallurgy is an advanced manufacturing technology for manufacturing metal parts through the process steps of mixing, pressing, sintering and the like of metal powder, has the advantages of high production efficiency, high material utilization rate, capability of manufacturing parts with complex shapes and the like, and is widely applied to the fields of aerospace, automobile manufacturing, mechanical engineering and the like. However, the conventional metal powder metallurgy process still faces some challenges in preparing high-performance alloy materials, such as fracture toughness, elongation and other mechanical properties of the materials are still to be further improved, so as to meet the strict requirements of the high-end application field on the material properties. For example, chinese patent application CN104226978a discloses an application of an aqueous solution of polyvinyl alcohol in metal powder metallurgy forming, and the invention uses the aqueous solution of polyvinyl alcohol as an adhesive to solve the problem of non-uniformity of product quality caused by volatile adhesive, and can be directly removed in sintering process, but the main focus is on improvement of the adhesive, which does not significantly contribute to improvement of mechanical properties of alloy material itself, and especially lacks effective measures in co-promotion of fracture toughness and elongation. For another example, chinese patent application CN113025859a discloses a high-strength high-plasticity tungsten alloy material and a preparation method thereof, and the material has a certain strength and plasticity matching through the proportion of specific components and the preparation process, but the invention is mainly aimed at a specific tungsten alloy material system, and the preparation process is relatively complex, and involves multiple steps of ball milling powder mixing, hot isostatic pressing sintering, solution aging treatment and the like, so that the universality of other types of metal powder metallurgy materials is limited, and there is still room for improvement in terms of further improving the toughness and crack resistance of the material. In summary, when the existing metal powder metallurgy technology is used for preparing high-performance alloy materials, the problems of difficulty in cooperative improvement of fracture toughness and elongation of materials, complex part of process, insufficient universality of different material systems and the like exist, and the application expansion of the metal powder metallurgy technology in the field with higher performance requirements is limited, so that development of a metal powder metallurgy forming process capable of effectively solving the problems is needed to meet urgent demands of modern industry on high-performance metal parts. Disclosure of Invention In order to solve the defects in the prior art, the invention aims to provide a metal powder metallurgy forming process with high fracture toughness and elongation. In order to achieve the above object, the present invention adopts the following technical scheme: A metal powder metallurgy forming process comprising the steps of: Step 1, metal powder material proportion, namely weighing tungsten, copper, nickel, iron and an interface toughening agent according to proportion, fully and uniformly mixing to obtain a metal mixture; step2, mould pressing, namely filling the mixture into a mould cavity, and performing mould pressing forming to obtain a green body; Step 3, sintering at high temperature, namely heating up to 350-450 ℃ at a heating rate of 1-5 ℃ per minute in a presintering section, preserving heat for 20-30min, continuously introducing hydrogen, preserving heat for 20-40min at a temperature of 1400-1600 ℃ in a sintering section, continuously introducing mixed gas, controlling the cooling temperature to be lower than 150 ℃ in a cooling section, and continuously introducing nitrogen in the cooling process to obtain a sintered blank; And 4, shaping, namely putting the sintered blank into a shaping die, applying cold pressing pressure, and performing secondary shaping when the size out-of-tolerance is more than 0.1mm to obtain the shaped alloy material. The weight ratio of each substance in the metal mixture is 2-6% of copper, 1-5% of nickel, 1-5% of iron, 1-5% of interface toughening agent and the balance of tungsten. The addition amount of the polyvinyl alcohol aqueous solution accounts for 5-15% of the total mass of the metal mixture, and the concentration of the polyvinyl alcohol aqueous solution is 5-20wt%. And (2) the unit pressing pressure of the compression molding in the step (2) is 0.5-1T/cm 2, and the pressure is maintained for 10-20 seconds after the compression. And