Pure Titanium Sheet Hot-Rolling Microstructure Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing cold-rolling process for titanium sheets faces challenges in maintaining sufficient ductility and preventing edge cracks when omitting the intermediate annealing step, leading to potential rolling failures and increased production costs.
Innovation Solution
A production method involving hot-rolling of pure titanium materials while coiling, followed by annealing to achieve a percentage area of recrystallized grains greater than or equal to 90% and a mean grain diameter of 5 μm to 10 μm, which inhibits edge crack generation during cold-rolling without the need for intermediate annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the intermediate annealing step is omitted to reduce production cost and simplify the process, then productivity is improved and production cost is reduced, but the ductility of the rolled sheet deteriorates and edge cracks may occur during cold-rolling
Solution Approach 1:
The patent applies preliminary action by optimizing the hot-rolling parameters (temperature range of 750-850°C, rolling reduction ratio of 80-95%, and coiling temperature of 200-500°C) before the cold-rolling step to pre-establish a microstructure that will prevent edge cracks during subsequent cold-rolling without requiring intermediate annealing. This preliminary preparation of the material state eliminates the need for the intermediate annealing step while maintaining ductility.
2Reliability
If the thickness of the rolled sheet after hot-rolling is reduced to decrease the total rolling reduction in the second cold-rolling step, then the risk of edge crack is reduced, but rolling failure in the hot-rolling step may occur and pickling yield in the annealing step is lowered
Solution Approach 1:
The patent applies parameter changes by optimizing the hot-rolling temperature (750-850°C) and rolling reduction ratio (80-95%) to achieve the appropriate sheet thickness and microstructure without causing rolling failure or reducing pickling yield. This controlled adjustment of processing parameters enables edge crack prevention during cold-rolling while maintaining hot-rolling process stability and annealing step effectiveness.
3Productivity
If a large increase in total rolling reduction is applied in the second cold-rolling step to compensate for omitted steps, then productivity is improved, but sufficient ductility cannot be maintained and edge crack and rupture may occur
Solution Approach 1:
The patent applies preliminary action by establishing the optimal microstructure during hot-rolling (with controlled cooling and coiling at 200-500°C) before cold-rolling, which enables the material to withstand the required rolling reduction without edge cracks or rupture. This preliminary microstructure preparation allows for process simplification while maintaining rolled sheet quality.
Solution Approach 2:
The patent applies parameter changes by controlling the microstructure parameters (grain size, phase composition) through hot-rolling parameters, which fundamentally changes the material's mechanical properties to enable higher rolling reduction without compromising quality or generating defects.
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 production costs by eliminating the intermediate annealing step while ensuring the rolled sheet's ductility and preventing edge cracks, allowing for efficient cold-rolling of high-quality pure titanium sheets.
Implementation Method 1
annealing a hot-rolled sheet formed by the hot-rolling
Implementation Method 2
a percentage area of recrystallized grains in a microstructure of the hot-rolled sheet after the annealing is greater than or equal to 90%
Data Source
AI summary
An aspect of the present invention is a production method of a rolled sheet for cold-rolling, the method being characterized by including: a hot-rolling step for forming a rolled sheet by hot-rolling a pure titanium material while coiling; and an annealing step for annealing the hot-rolled sheet after the hot-rolling step, the coiling temperature in the hot-rolling step being 500° C. or less, and the annealing step being controlled so that the percentage area of recrystallized grains in the microstructure of the hot-rolled sheet after annealing is at least 90% and the mean grain size of the recrystallized grains is 5 μm to 10 μm.