Metal laser melting additive manufacturing method

Abstract

The invention discloses a metal laser melting additive manufacturing method. After each layer is machined by utilizing the laser additive manufacturing method, a single-layer laser photocoagulation area is modified by utilizing a selective friction stir welding, photocoagulation cracks are eliminated and nanocrystalline is formed. Each additive-manufactured layer is subjected to laser melting and friction stir welding and multiple layers are machined by the method repeatedly, so that nanocrystalline complex metal components with high strength and ductility and no cracks are manufactured. The laser melting additive manufacturing method provided by the invention comprises a selective laser melting technique based on powder bed formation and a laser engineering near-net forming technique based on laser coaxial powder feeding, wherein the involved metal materials comprise an aluminum base, a copper base, a titanium base, an iron base, a nickel base and a cobalt base; the selective friction stir welding can eliminate cracks, balling and holes generated during laser additive manufacturing and improves the formation quality; the selective friction stir welding can crush network carbides in a laser photocoagulation structure, so that the crushed network carbides are distributed in a dispersion manner, and the structure is regulated to be the nanocrystalline.

Description

technical field [0001] The invention belongs to the field of additive manufacturing, and specifically relates to layer-by-layer laser melting additive manufacturing and selective area stir friction composite technology, which can realize the manufacture of crack-free, nano-crystalline, high-strength and tough metal parts. Background technique [0002] Laser melting additive manufacturing technology, also known as laser melting 3D printing, is an advanced manufacturing technology that has developed rapidly in recent years. The laser melting additive manufacturing technology of metal parts melts metal powder layer by layer through high-energy laser beams, and then realizes the manufacture of arbitrary complex metal parts, but there are still the following technical bottlenecks: [0003] First, due to the characteristics of rapid heating and rapid cooling in the laser additive manufacturing process, high-gradient heat-force-flow multi-field coupling, etc., there are high therma...

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Problems solved by technology

However, due to the extremely complicated solidification process of the laser molten pool, the above-mentioned crack prevention methods still have certain limitations: first, the above methods are difficult to completely eliminate micro-cracks, especially for highly crack-sensitive materials such as nickel-based and cobalt-based materials; secondly, the above methods are difficult universally applicable

[0004] Second, the brittle ceramic phase (such as M 7 C 3 ,M 23 C 6 ) are easily distributed around the matrix grains in a continuous network structure, which greatly reduces the strength and toughness of laser additive manufacturing

Although the presence of ceramic phases can greatly improve the hardness and wear resistance of laser additive manufacturing parts, these ceramic phases distributed in a network form isolate the metal grains from each other, greatly weakening the bonding force between the grains, resulting in laser The overall performance of additively manufactured parts is brittle. When laser additively manufactured parts are in service under external loads, the stress is difficult to transfer, which can lead to crack initiation and workpiece failure.

However, there is no literature on the elimination method of such network carbides

Although heat treatment can reduce carbide content and segregation to a certain extent, it is difficult to completely change the continuous network distribution of thick carbides. On the other hand, heat treatment cannot eliminate microscopic cracks.

[0005] Third, the forming process of laser additive manufacturing is also prone to spheroidization and pores, which greatly affect the forming effect of laser additive manufacturing and the mechanical properties of formed parts. The bottleneck problem affects the promotion of laser additive manufacturing to high-performance metal parts

The combination of this processing method and laser melting additive manufacturing technology has not yet been reported.

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