Titanium Hot Rolling Dimples for Surface Defect Reduction
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Solution Overview
Problem
The coarse solidified structure of titanium ingots leads to surface defects during the hot rolling process, including wrinkles and edge cracks, due to uneven deformation and the presence of dead metal zones, which reduces yield and product quality.
Innovation Solution
A titanium material for hot rolling with dimples imparted by cold plastic deformation using a steel tool or sphere with a radius of curvature of 3 to 30 mm, allowing for recrystallization and reducing surface defects by forming a thick recrystallized layer, thereby omitting the ingot breakdown process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the ingot is directly hot rolled without breakdown process, then production cost is reduced and productivity is improved, but surface defects occur due to coarse crystal grains causing uneven deformation
Solution Approach 1:
The patent applies preliminary action by performing cold plastic deformation on the ingot surface before hot rolling to create dimples. This pre-treatment modifies the surface structure in advance, enabling the coarse-grained ingot to be directly hot rolled without breakdown while preventing surface defects during the subsequent hot rolling process.
Solution Approach 2:
The patent applies local quality by creating dimples only on the surface layer of the ingot through cold plastic deformation, while the internal structure remains unchanged. This localized modification allows the surface to resist defect formation during hot rolling without requiring breakdown of the entire ingot, thus maintaining productivity while improving surface quality.
2Ease of manufacture
If breakdown process is omitted, then manufacturing cost is reduced, but dead metal zones remain causing surface defects during hot rolling
Solution Approach 1:
The patent performs cold plastic deformation to create dimples on the ingot surface before hot rolling, eliminating dead metal zones in advance. This preliminary action prevents surface defects during hot rolling without requiring the breakdown process, thereby reducing manufacturing cost while eliminating harmful surface defects.
Solution Approach 2:
The patent changes the surface structure parameter by creating dimples through cold plastic deformation. This parameter change modifies the surface morphology and eliminates dead metal zones, allowing direct hot rolling without breakdown while preventing surface defects caused by unchanged internal structures.
3Manufacturing precision
If cold plastic deformation creates dimples with appropriate dimensions, then surface defects are reduced, but additional process steps are required
Solution Approach 1:
The patent specifies precise parameter ranges for dimple dimensions (depth: 0.05-2.0mm, diameter: 1-20mm) to achieve surface defect reduction. By defining these specific parameters, the patent transforms a complex quality control problem into a manageable parameter optimization task, reducing surface defects while keeping the process relatively simple.
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
The method significantly reduces surface defects on flat materials, side surfaces, and edges during hot rolling, enhancing product quality and yield, and allows for direct hot rolling of rectangular or cylindrical ingots without the need for breakdown processes.
Implementation Method 1
dimples imparted by cold plastic deformation whose mean value of the heights (Wc) of the undulation profile elements is 0.2 to 1.5 mm and mean value of the lengths (WSm) thereof is 3 to 15 mm
Implementation Method 2
the surface is then recrystallized to a depth of 2 mm or greater by heating to the recrystallization temperature or higher
Data Source
Figure 1(a)~1(b)
Figure 2(a)~4(b)
Figure 5(a)~5(b)
AI summary
The present invention provides a titanium material for hot rolling that enables reduction of defects occurring on the surface (in the case of a flat material or strip coil, including not only the flat surfaces but also the side surfaces and edges) owing to the hot rolling, and a method of producing the same, particularly to a titanium material for hot rolling enabling omission of an ingot breakdown process, and a method of producing the same, characterized in that it is a titanium material for hot rolling having dimples imparted by cold plastic deformation whose mean value of the heights (Wc) of the undulation profile elements is 0.2 to 1.5 mm and mean value of the lengths (WSm) thereof is 3 to 15 mm, and makes it possible to minimize surface defects occurring in hot rolling even if a process for breaking down the ingot is omitted. The dimples are formed by plastically deforming the surface of the titanium under cold condition using a steel tool having a tip shape of a radius of curvature of 3 to 30 mm or a steel sphere of a radius of 3 to 30 mm.