Large Isothermal Forging Die Blank Diffusion Bonding for Uniform TZM Alloy
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Solution Overview
Problem
The existing methods for preparing large-scale titanium-zirconium-molybdenum alloy die blanks for vacuum isothermal forging face challenges such as uneven structures, poor welding performance, and increased manufacturing complexity due to the high melting point and deformation resistance of the alloy, leading to difficulties in achieving uniform bonding and maintaining mechanical properties.
Innovation Solution
An additive manufacturing method involving the preparation of plate-shaped titanium-zirconium-molybdenum alloy units and foil-shaped intermediate layers of tantalum, niobium-tungsten, or tantalum-tungsten alloys, followed by diffusion bonding and homogenization under controlled temperature and pressure conditions to form a diffusion layer, thereby enhancing bonding and maintaining the alloy's microstructure and properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional forging or rolling is used to refine grains and modify large-scale die blanks, then the alloy structure can be improved, but the process becomes extremely difficult due to high deformation resistance at high temperature
Solution Approach 1:
The large-scale die blank is divided into multiple small units that are stacked and bonded together. This segmentation allows each unit to be manufactured with controlled size and uniform structure, avoiding the high deformation resistance issues of processing large monolithic blanks. The units are then assembled into the final large-scale component through diffusion bonding.
Solution Approach 2:
The invention changes the processing parameters by using diffusion bonding at temperatures below the recrystallization temperature (1350-1400°C) rather than conventional hot forging temperatures. This parameter change enables bonding without requiring high deformation resistance, thus avoiding the manufacturing difficulties while achieving uniform structure through controlled diffusion processes.
2Reliability
If electron beam welding is used to encapsulate small units, then vacuum state between units can be achieved, but welding performance is poor and microstructure changes significantly due to high temperature
Solution Approach 1:
A foil-shaped intermediate layer is introduced between the plate-shaped alloy units during diffusion bonding. This intermediate layer acts as a mediator that facilitates bonding while controlling the thermal and diffusion processes, preventing direct high-temperature exposure that would cause significant microstructure changes. The intermediate layer enables vacuum state achievement without the harmful effects of electron beam welding.
3Strength
If large deformation amount is applied by forging to realize interdiffusion, then bonding between units can be achieved, but the alloy is difficult to deform due to high deformation resistance at high temperature
Solution Approach 1:
The invention replaces the mechanical deformation system (forging with large deformation amounts) with a diffusion-based system. Instead of relying on mechanical pressure and plastic deformation to achieve bonding, the process uses thermal diffusion at controlled temperatures below recrystallization, eliminating the need for high deformation capability while achieving strong bonding between units.
4Volume of stationary object
If the size of die blank is increased, then the application scope is expanded, but mechanical property decreases rapidly due to uneven structures and chemical distribution
Solution Approach 1:
The large-scale die blank is segmented into multiple small units with controlled dimensions that can be manufactured with uniform structure and composition. By stacking and bonding these uniformly prepared units, the final large-scale component maintains the mechanical properties of the smaller units while achieving the required size, thus expanding application scope without sacrificing strength.
Solution Approach 2:
Each small unit in the stacked structure is manufactured with controlled local quality parameters (size, composition, microstructure) to ensure uniformity. The diffusion bonding process then creates localized diffusion zones at the interfaces while maintaining the overall uniformity of the component, ensuring consistent mechanical properties throughout the large-scale die blank.
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 effectively reduces structural and compositional non-uniformity, improves high-temperature performance, and simplifies the manufacturing process by promoting interdiffusion and forming strong diffusion layers at bonding interfaces, resulting in improved mechanical properties and reduced manufacturing costs.
Implementation Method 1
applying an axial pressure of 6-9 MPa for bonding time not less than 3 hours to the assembly body at a bonding temperature 20-100° C. lower than the recrystallization temperature of the titanium-zirconium-molybdenum alloy and a vacuum degree of 10−3-10−2 Pa by means of a vacuum diffusion welding furnace, so that diffusion bonding between the plated-shaped units of titanium-zirconium-molybdenum alloy and the foil-shaped intermediate layer occurs
Implementation Method 2
homogenizing the primary blank for a homogenization time of 2-24 hours at a homogenization temperature 50-150° C. lower than the recrystallization temperature of the titanium-zirconium-molybdenum alloy under vacuum or inert gas protection, to homogenize the microstructure and composition at bonding interfaces in the primary blank
Data Source
AI summary
An additive method for preparing a large die blank for isothermal forging comprising preparing a plurality of titanium-zirconium-molybdenum alloy plate-shaped elements of a preset shape; preparing a plurality of foil-shaped intermediate layers of pure tantalum, a niobium-tungsten alloy and a tantalum-tungsten alloy of a preset shape; forming an assembly of a preset configuration, such that the foil-shaped intermediate layers are sandwiched between the titanium-zirconium-molybdenum alloy plate-shaped elements; applying an axial pressure to the assembly under high-temperature vacuum to perform diffusion connections to obtain a primary blank; subjecting the primary blank to a homogenization treatment under a high temperature, vacuum or inert gas protection to homogenize the structure and components at a connection interface in the primary blank; and cooling the homogenized primary blank to obtain a die blank.