Method of achieving full density binder jet printed metallic articles

Abstract

A method of producing full density binder-jet printed metallic articles. A metallic 3-D printed article is produced using a binder-jet printing method and is positioned in a hot isostatic press (HIP) container surrounded by stabilization powder. A vacuum is introduced into the inside of the HIP container. A binder used to bond powder articles together in the printed article is removed by heating the HIP container to decompose the binder and removing decomposition products by applying a vacuum to the HIP container. The HIP container is sealed with a vacuum therein and compacted under heat and pressure to remove all porosity in the printed article. The printed article thereafter is removed from the HIP container and finished to a final form.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]This application claims the priority of Provisional Patent Application No. 62 / 088,009 filed on Dec. 5, 2014 and entitled ACHIEVING FULL DENSITY BINDER JET PRINTED METALLIC ARTICLES.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to binder-jet printing and, more particularly, to the use of binder-jet printing and hot isostatic press (HIP) processing in the preparation of printed metallic articles.[0004]2. Description of the Background Art[0005]Additive manufacturing has been demonstrated to be highly effective for rapid prototyping and small lot production for plastic articles. More recently, the application of additive manufacturing to metallic materials has been growing, first in medical, dental and specialty consumer products, and now developing in aerospace applications.[0006]The benefits of direct metal additive manufacturing are best realized in applications involving: high material loss...

AI Technical Summary

Benefits of technology

The patent text describes a new process for making high-quality titanium and superalloy parts using a combination of binder-jet printing and hot isostatic pressing (HIP). The process solves two common issues associated with traditional methods: the difficulty in achieving full density and the need for expensive powder. The new process involves packing the printed parts in a container with shape-stabilizing powder and conducting thermal operations at temperatures below the beta transus. The process can also be carried out using a vacuum to maintain shape retention. This new method can reduce costs and allow for the use of lower-cost powder.

Problems solved by technology

Undesirable Microstructural Modification

Some specialty alloys such as titanium or superalloys experience undesirable microstructural changes when processed using e-beam or laser direct melt fusion or the high temperature sintering near the melt temperature used to densify binder-jet printed articles.

The above methods have restrictions on powder size that significantly impact cost.

Since spherical powder is the most desirable for these processes and spherical powder cost is greatest for fine particle sizes, the need for fine powder size in the binder-jet process adds significantly to cost.

This limits the amount of material that can be deposited and the size of the article that can be built without experiencing residual stress cracking.

This adds cost and time to the process.

This process can create a sintered article, however, the sintering temperatures are typically close to the melt temperature, above the solids but below the liquids, to achieve near full density creating undesirable microstructural modifications and in some cases requiring extremely long sintering times.

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