Titanium Cast Product Surface Refinement via Electron Beam Melting
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Solution Overview
Problem
The existing methods for producing titanium cast products for hot rolling, such as direct cast slab casting, often result in surface defects due to coarse cast structures, leading to reduced productivity and increased costs, as they require surface cutting and hot rolling processes that are inefficient and costly.
Innovation Solution
A titanium cast product with a fine structure layer formed by electron beam irradiation, where the melting depth is controlled between 5 mm and 9 mm, and the cooling rate is optimized to prevent concavities and surface defects, allowing for hot rolling without pre-treatment modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a breakdown step (slabbing or forging) is performed on large-sized cast products, then the surface quality after hot rolling is improved, but the production time and cost increase significantly
Solution Approach 1:
The invention extracts and eliminates the breakdown step (slabbing or forging) from the conventional production process. By using direct cast slabs with controlled thickness (10-50mm) produced through DC slab casting, the process removes the time-consuming breakdown operation while maintaining surface quality through optimized casting parameters and subsequent hot rolling
Solution Approach 2:
The invention changes the critical parameter of slab thickness from the conventional large-sized cast products to a controlled range of 10-50mm. This parameter change, achieved through DC slab casting with specific cooling rates and casting conditions, enables direct hot rolling without breakdown while ensuring surface quality
2Productivity
If the breakdown step is omitted and DC slab casting is used directly, then productivity improves and cost reduces, but surface defects occur due to coarse cast structure
Solution Approach 1:
The invention changes the casting parameters by controlling the slab thickness to 10-50mm and optimizing the cooling rate during DC slab casting. These parameter changes produce a refined cast structure that eliminates surface defects while maintaining the productivity benefits of omitting the breakdown step
Solution Approach 2:
The invention performs preliminary action by optimizing the casting process itself to produce slabs with suitable surface quality. Through controlled DC slab casting with specific parameters (thickness, cooling rate, vacuum atmosphere), the surface quality is prepared in advance, eliminating the need for both breakdown and surface cutting operations
3Manufacturing precision
If surface cutting is performed to remove oxide layers and defects, then surface quality improves, but material yield decreases and additional time and cost are required
Solution Approach 1:
The invention extracts and eliminates the surface cutting operation from the production process. By optimizing DC slab casting to produce slabs with inherent surface quality and controlling hot rolling parameters, the process removes the need for surface cutting, thereby maintaining material yield while ensuring surface quality
Solution Approach 2:
The invention performs preliminary action by preventing surface defect formation during the casting and hot rolling processes. Through optimized casting parameters and hot rolling conditions, the surface quality is maintained throughout processing, eliminating the need for corrective surface cutting operations
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 effectively eliminates surface defects and concavities, improving the productivity and cost-effectiveness of titanium hot rolled sheet production by ensuring a fine structure layer that prevents defects during hot rolling, even without a breakdown step like slabbing or forging.
Implementation Method 1
the surface of a cast product is heated and only the surface layer is melted by a heating means with a high energy density such as an electron beam
Implementation Method 2
the cooling performed after the surface of a cast product is heated and only the surface layer is melted by a heating means with a high energy density such as an electron beam is usually performed by heat removal from the matrix side
Data Source
AI summary
Provided is a titanium cast product for hot rolling made of commercial pure titanium or a titanium alloy, the titanium cast product including, in a surface serving as a rolling surface, a fine structure layer that is formed of an acicular structure formed in the outermost surface by melting and re-solidification treatment and that has a thickness of more than or equal to 5 mm and less than 9 mm in depth. In the titanium cast product for hot rolling according to the present invention, the surface is flat, the number of minute voids in the interior immediately below the surface is small, and the outermost surface has a significantly fine structure. When the titanium cast product is subjected to hot rolling, the occurrence of concavities on the surface in the early stage of hot rolling and the occurrence of surface defects on the hot rolled sheet can be stably prevented at a practical level.