Titanium Slab Surface Refinement via Electron Beam Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for manufacturing titanium sheets using commercially pure titanium cast products face challenges in productivity and cost due to the need for a breakdown process and surface cutting work to prevent surface flaws in hot rolled sheets, which are time-consuming and labor-intensive, and often result in incomplete removal of defects like voids and coarse microstructure.
Innovation Solution
A method involving a two-stage surface heat treatment process using electron beam heating to refine the microstructure of titanium cast products, where the first stage heats a depth of 6-20 mm to the β transformation point and the second stage heats a depth of 1-6 mm, followed by rapid cooling, to create a microstructural refinement layer with acicular microstructure, effectively eliminating surface flaws and internal voids without the need for surface cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the breakdown process (slab rolling or forging) is used to deform the large cast product into a slab, then the surface quality is improved, but the manufacturing time and cost increase significantly
Solution Approach 1:
The invention extracts and removes the harmful coarse cast microstructure from the surface layer through selective melting and rapid solidification, eliminating the need for the traditional breakdown process while maintaining surface quality
Solution Approach 2:
The invention changes the microstructural parameters of the surface layer by controlling the melting and rapid solidification process, transforming the coarse cast microstructure into a fine equiaxed grain structure that prevents surface flaws
2Manufacturing precision
If surface cutting work is performed to remove the oxide layer and oxygen-enriched layer, then the surface quality is improved, but the manufacturing cost and time increase
Solution Approach 1:
The invention changes the surface microstructure parameters through controlled melting and rapid solidification, creating a fine-grained surface layer that eliminates surface flaws without requiring mechanical cutting or removal of the oxide layer
3Productivity
If the DC slab casting method is used to produce a slab-shaped cast product directly, then the productivity is improved and manufacturing cost is reduced, but surface flaws are formed on the hot rolled sheet
Solution Approach 1:
The invention applies local quality transformation by selectively treating only the surface layer through melting and rapid solidification, creating a fine-grained surface structure while maintaining the efficiency of direct slab casting
Solution Approach 2:
The invention changes the microstructural parameters of the surface layer by controlling the melting depth and cooling rate, transforming the coarse cast microstructure into a fine equiaxed grain structure that prevents surface flaws
4Ease of manufacture
If coarse cast microstructure is present in the surface layer, then the manufacturing process is simplified, but surface flaws are formed on the hot rolled sheet
Solution Approach 1:
The invention changes the microstructural parameters of the surface layer through controlled melting and rapid solidification, transforming the coarse cast microstructure into a fine equiaxed grain structure that prevents surface flaws while maintaining process simplicity
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 a titanium cast product with a smooth surface and fine microstructure, significantly reducing surface flaws and internal defects, thereby improving the manufacturing efficiency and reducing costs by eliminating the need for the breakdown process and surface cutting work.
Implementation Method 1
a surface of a cast product is heated by heating means having a high energy density such as an electron beam to melt only a surface layer
Implementation Method 2
heating a surface of a cast product to be rolled in hot rolling to heat a region of a depth of 6 mm or more and 20 mm or less from the surface to a β transformation point or higher and to melt a range of a depth of 3 mm or more and 10 mm from the surface
Implementation Method 3
the cast product is cooled by removing heat to a parent metal side
Implementation Method 4
cooling the cast product material to temperature lower than the β transformation point after the first stage surface heat treatment process
Implementation Method 5
heating a surface of a cast product to be rolled in hot rolling to heat a region of a depth of 6 mm or more and 20 mm or less from the surface to a β transformation point or higher
Implementation Method 6
a first stage surface heat treatment process of heating a surface of a cast product material composed of commercially pure titanium to be rolled in hot rolling to heat a region of a depth of 6 mm or more and 20 mm or less from the surface to a β transformation point or higher and to melt a range of a depth of 3 mm or more and 10 mm from the surface
Data Source
Figure 1
Figure 2
Figure 3(A)~3(B)
AI summary
There is provided a titanium cast product for hot rolling composed of commercially pure titanium, the titanium cast product including: a microstructural refinement layer having acicular microstructure on an outermost layer of a surface layer to be rolled; and an inside microstructural refinement layer having acicular microstructure provided in an inside of the microstructural refinement layer. Cast solidification microstructure is present more inward than the inside microstructural refinement layer. The microstructural refinement layer has finer microstructure than the inside microstructural refinement layer. The microstructural refinement layer is present in a range of a depth of 1 mm or more and less than 6 mm from the surface. The inside microstructural refinement layer is present in an inside of the microstructural refinement layer in a range of a depth of 3 mm or more and 20 mm or less from the surface.