Thermal-Hydrogen Processing for Additive Manufactured Titanium Microstructure

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Solution Overview

Problem

Additive manufacturing of metal alloys, such as titanium, often results in parts with mechanical property anisotropy due to columnar structures along the build direction, leading to inconsistent mechanical properties and reduced fatigue strength.

Innovation Solution

Thermal-hydrogen processing (THP) is applied to refine the microstructure of additive manufactured components by using hydrogen as a temporary alloying element, involving hydrogenation and dehydrogenation to alter mechanical properties, where hydrogen diffuses into the metal during heat treatment and is removed during dehydrogenation, effectively changing the microstructure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If additive manufacturing is used to manufacture metal alloy parts, then material waste is reduced and manufacturing efficiency is improved, but the parts exhibit mechanical property anisotropy and reduced fatigue strength

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidfatigue strength

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies thermal-hydrogen processing to change the microstructural parameters of additive manufactured parts. By controlling hydrogen diffusion during heat treatment at specific temperatures and durations, the columnar grain structure is transformed into a refined equiaxed grain structure, thereby improving mechanical properties and fatigue strength while maintaining the productivity benefits of additive manufacturing

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes hydrogen as a temporary alloying element during heat treatment. Hydrogen diffuses into the metal matrix, forms hydrides, and facilitates grain boundary migration and recrystallization. After processing, hydrogen is removed, leaving a refined microstructure. This temporary composite approach enables microstructural transformation without permanent hydrogen contamination

Inventive Principle:

Principle #40Composite materials

2Loss of substance

If additive manufacturing is used to manufacture metal alloy parts, then material waste is reduced, but the parts exhibit columnar structures leading to mechanical property anisotropy

Engineering Contradiction:

Improvematerial wasteVSAvoidmicrostructure uniformity

Core Design Contradiction:

Loss of substanceVSStability of the object's composition

Solution Approach 1:

The patent changes thermal and compositional parameters during heat treatment to transform the microstructure. By controlling temperature, hydrogen potential, and time, the columnar structure formed during additive manufacturing is converted into a uniform equiaxed grain structure, achieving microstructural stability without sacrificing the material efficiency of additive manufacturing

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Hydrogen acts as an intermediary substance during the microstructural transformation. It facilitates grain boundary migration and recrystallization processes that equate the microstructure throughout the part. After serving its purpose, hydrogen is removed, leaving a uniform microstructure without permanent alteration to the base metal composition

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

THP refines the microstructure, reducing mechanical property anisotropy and resulting in a more uniform and finer structure, enhancing the fatigue strength and mechanical properties of the components.

Implementation Method 1

hydrogen diffuses into the metal during heat treatment and is removed during dehydrogenation

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

heat treating the hydrogenated titanium

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentEP3563949B1Additive manufacturing methods

Publication Date: 2022.11.02 THE BOEING CO

Figure 1A~1B
Figure 2A~2B
Figure 3A~3B

AI summary

An additive manufacturing method includes using hydrogenated titanium in forming an object by additive manufacturing, the object having a first microstructure. The method includes heat treating the hydrogenated titanium and, after completing a shape of the object, dehydrogenating the object. The dehydrogenated object has a second microstructure different from the first microstructure. Also, another additive manufacturing method includes forming an object containing Ti--6AI--4V, the object having a first microstructure containing columnar structures along a build direction of the additive manufacturing and the object exhibiting mechanical property anisotropy resulting from the columnar structures. After completing a shape of the object, the method includes hydrogenating the Ti--6AI--4V, heat treating the object containing the hydrogenated titanium, and dehydrogenating the heat treated object. The method reduces mechanical property anisotropy and the dehydrogenated object has a second microstructure different from the first microstructure.