Titanium Alloy UAM Welding with Vanadium Interlayer Bonding

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Solution Overview

Problem

The welding of titanium alloys, particularly Ti-6Al-4V, is challenging due to oxygen embrittlement at high temperatures and unwanted distortions caused by low thermal conductivity, making it difficult to achieve strong and reliable joints using ultrasonic additive manufacturing (UAM).

Innovation Solution

Introducing a vanadium interlayer between Ti-6Al-4V layers and applying a post-weld heat treatment process, including solution treatment, water quenching, and aging, to facilitate phase transformations and improve bonding strength, while using ultrasonic additive manufacturing to create high strain rate plastic deformation and collapse surface asperities below the melting temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ultrasonic additive manufacturing is used to weld titanium alloy layers, then the process can operate below melting temperature avoiding oxygen embrittlement, but the weld strength is insufficient due to low thermal conductivity and material resistance to bonding

Engineering Contradiction:

Improveweld strengthVSAvoidbonding difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

A metallic interlayer is introduced between the titanium alloy layers to facilitate bonding. The interlayer acts as a mediator that improves wetting and adhesion between the difficult-to-weld titanium surfaces, enabling stronger joints while maintaining the solid-state welding advantages of UAM

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The process utilizes high strain rate plastic deformation through ultrasonic vibration to change the physical state of the material interface. This dynamic parameter change enables surface asperity collapse and intimate contact between layers, overcoming the low thermal conductivity issue while achieving reliable bonds

Inventive Principle:

Principle #35Parameter changes

2Strength

If high temperature welding is applied to titanium alloy, then bonding strength can be improved, but oxygen embrittlement occurs at high temperatures

Engineering Contradiction:

Improvebonding strengthVSAvoidoxygen embrittlement

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The process replaces thermal welding mechanisms with ultrasonic mechanical vibration. The high-frequency mechanical oscillation generates localized plastic deformation and frictional heating at the interface, achieving strong bonds without bulk material heating that would cause oxygen embrittlement

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The metallic interlayer serves as a protective barrier that prevents oxygen diffusion into the titanium alloy during the welding process, eliminating oxygen embrittlement while still allowing strong bonding to occur

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If ultrasonic vibration is applied to create high strain rate deformation, then surface asperities can be collapsed for better bonding, but the process complexity increases

Engineering Contradiction:

Improvesurface contact qualityVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Ultrasonic vibration is applied through a horn that contacts the top surface of the stacked layers. This mechanical vibration method is relatively simple to implement and effectively collapses surface asperities to create intimate contact between layers, achieving high manufacturing precision

Inventive Principle:

Principle #18Mechanical vibration

Solution Approach 2:

The ultrasonic energy is concentrated at the local interface between layers rather than affecting the entire workpiece. This localized action achieves high surface contact quality at the bonding interface without requiring complex system-wide modifications

Inventive Principle:

Principle #3Local quality

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

This method enables the production of high-strength joints and 3D-printed Ti-6Al-4V parts with improved weld strength and mechanical properties, overcoming the limitations of UAM in bonding difficult-to-weld materials like titanium alloys.

Implementation Method 1

applying a horn of an ultrasonic device to the second layer of Ti alloy to weld the first layer of Ti alloy to the second layer of Ti alloy

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

creating high strain rate plastic deformation and collapse surface asperities below the melting temperature

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Implementation Method 3

applying a post-weld heat treatment process, including solution treatment, water quenching, and aging, to facilitate phase transformations and improve bonding strength

Methodology Applied

Scientific EffectPhase transformation: Phase Change

Data Source

PatentUS20240227061A1Welding and post-welding treatment of titanium alloy made via ultrasonic additive manufacturing

Publication Date: 2024.07.11 OHIO STATE INNOVATION FOUND

AI summary

A method of welding a first layer of Ti alloy to a second layer of Ti alloy. The method includes disposing a metallic interlayer onto a first layer of Ti alloy, disposing the second layer of Ti alloy onto the metallic interlayer such that the metallic interlayer is disposed between the first layer of Ti alloy and the second layer of Ti alloy, and applying a horn of an ultrasonic device to the second layer of Ti alloy to weld the first layer of Ti alloy to the second layer of Ti alloy to form a welded material.