Alpha+Beta Titanium Forming for Fine Prior Beta Grain Control
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Solution Overview
Problem
Manufacturing of components from α+β Ti alloys often results in relatively coarse prior β grain sizes, adversely affecting mechanical properties such as fatigue crack growth, fracture toughness, tensile strength, and ductility, leading to non-compliant components and reduced yield.
Innovation Solution
A method involving thermomechanical forming with controlled true strains and temperatures below the beta transus temperature, including multiple iterations of heating and deforming the precursor to achieve a total true strain greater than a predetermined threshold, thereby limiting the formation of coarse β grains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional thermomechanical forming is used to manufacture components from α+β Ti alloys, then manufacturing process is simple and production efficiency is maintained, but the prior β grain size becomes coarse which adversely affects mechanical properties
Solution Approach 1:
The thermomechanical forming process is divided into multiple discrete steps, each with controlled true strain increments. The total true strain is accumulated through several forming operations rather than a single step, allowing precise control over grain refinement while managing process complexity through systematic breakdown of the forming sequence.
Solution Approach 2:
The process controls and adjusts key parameters including true strain per step, temperature ranges, and number of forming steps to achieve the desired grain size. By modifying these parameters systematically, the patent achieves fine prior β grain size control while maintaining an economically viable manufacturing process.
2Strength
If conventional thermomechanical forming is used, then production time and cost are controlled, but mechanical properties such as fatigue crack growth and fracture toughness are adversely affected due to coarse grain size
Solution Approach 1:
The forming process is segmented into multiple steps with controlled true strain accumulation. This segmentation allows the material microstructure to be refined progressively, improving fatigue and fracture properties without requiring excessive total forming time, thus balancing strength improvement with manufacturing efficiency.
Solution Approach 2:
By optimizing parameters such as true strain per step, temperature control ranges, and number of forming operations, the process achieves fine grain size for improved mechanical properties while minimizing the impact on overall production time and cost.
3Reliability
If conventional thermomechanical forming is used, then manufacturing process is straightforward, but a proportion of components exhibit coarse prior β grain size leading to non-compliance and disposal
Solution Approach 1:
The forming process is divided into multiple controlled steps with specified true strain increments. This segmentation ensures consistent grain refinement across all components, reducing variability and improving compliance rates while maintaining manageable process control through systematic step-by-step procedures.
Solution Approach 2:
The patent establishes specific parameter ranges for true strain per step, temperature control, and number of forming operations. These controlled parameter changes ensure reproducible fine grain size results, thereby improving component compliance rates while keeping the process control complexity within acceptable limits.
4Productivity
If conventional thermomechanical forming is used, then manufacturing cost is controlled, but yield is reduced due to disposal of non-compliant components with coarse grain size
Solution Approach 1:
The forming process is segmented into multiple controlled steps that systematically refine the grain structure. This approach ensures higher compliance rates and reduces waste, improving yield. The segmented nature of the process allows for better quality control without prohibitively increasing complexity.
Solution Approach 2:
By optimizing and controlling parameters such as true strain per step, temperature ranges, and number of forming operations, the process achieves consistent fine grain size results that meet specifications, thereby reducing scrap and improving manufacturing yield while maintaining economically acceptable process complexity.
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 approach results in components with finer β grain sizes, improving mechanical properties like fatigue resistance, fracture toughness, tensile strength, and ductility, thereby increasing yield and compliance with manufacturing specifications.
Implementation Method 1
heating the first portion to a temperature Ti during a time ti, wherein the temperature Ti is at most the beta transus temperature βtransus
Implementation Method 2
deforming the heated first portion by a true strain ε1,i, wherein the true strain ε1,i is at most the predetermined threshold true strain εthreshold
Data Source
AI summary
A method of thermomechanically forming, for example forging, rolling, extruding or drawing, an article from a precursor thereof, is described. The method comprises: providing the precursor, for example an ingot, a forging stock, a forging, a bar, a billet or a plate, comprising, substantially comprising, essentially comprising and/or consisting of an α+β Ti alloy having a beta transus temperature βtransus, wherein the precursor defines a set of portions including a first portion; and thermomechanically forming the article from the precursor by heating the first portion and deforming the heated first portion by a total true strain ε1, total, wherein the total true strain ε1, total is greater than a predetermined threshold true strain εthreshold; wherein thermomechanically forming the article from the precursor comprises i iterations of: (a) heating the first portion to a temperature Ti during a time ti wherein the temperature Ti is at most the beta transus temperature βtransus; (b) deforming the heated first portion by a true strain ε1,i, wherein the true strain ε1,i is at most the predetermined threshold true strain εthreshold and (c) repeating steps (a) and (b) until the cumulative true strain ε1, cumulative=Σiε1,ieu is the total true strain ε1, total wherein i is a natural number greater than or equal to 2.