Ti Microalloyed Steel Coil Slow Cooling for Uniform TiC Precipitation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for improving the precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel are inefficient and prone to temperature inconsistencies, particularly in slow cooling processes, which affect the uniformity and effectiveness of TiC precipitation.
Innovation Solution
A method involving controlled rolling, cooling, and coiling of Ti microalloyed steel, followed by immediate on-line insulation using an independent closed enclosure for slow cooling, ensuring uniform temperature homogenization and nano-scale TiC precipitation, thereby enhancing the precipitation strengthening effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If slow cooling process is used to improve precipitation strengthening effect, then TiC precipitation is promoted, but temperature uniformity deteriorates and surrounding environment affects the process
Solution Approach 1:
The patent divides the cooling process into two distinct stages: rapid cooling stage (from finishing rolling temperature to coiling temperature) and slow cooling stage (from coiling temperature to room temperature). This segmentation allows each stage to optimize for its specific purpose - rapid cooling for initial structure formation and slow cooling for uniform TiC precipitation - thereby resolving the contradiction between strengthening effect and temperature uniformity.
Solution Approach 2:
The patent changes the cooling rate parameter dynamically: high cooling rate during the first stage to achieve rapid temperature reduction, then transitions to low cooling rate (10-50°C/hour) in the second stage to ensure uniform TiC precipitation throughout the steel coil while maintaining temperature homogeneity. This parameter change resolves the contradiction by adapting the cooling rate to the specific requirements of each precipitation phase.
2Strength
If conventional slow cooling methods are used, then precipitation strengthening is enhanced, but additional equipment and process complexity increase
Solution Approach 1:
The patent utilizes the steel coil's own residual heat after hot rolling as the heat source for the slow cooling process. The coil naturally retains sufficient thermal energy to maintain slow cooling without requiring external heating equipment, thereby achieving yield strength enhancement while avoiding additional complex equipment installation.
Solution Approach 2:
The existing coiling equipment performs dual functions: it serves as both the coiling mechanism for hot steel and the starting point for the slow cooling process. The patent integrates the slow cooling function into the existing production line infrastructure, making the coiling system multi-functional and avoiding the need for separate dedicated slow cooling equipment.
3Strength
If Ti content is increased to enhance precipitation strengthening, then strength improves, but cost and potential harmful effects increase
Solution Approach 1:
The patent optimizes the Ti content parameter within a specific range (0.01-0.05%) and combines it with controlled cooling rate parameters to achieve uniform TiC precipitation. By precisely controlling both composition and process parameters, the patent maximizes tensile strength while avoiding the harmful effects of excessive Ti addition or non-uniform precipitation.
Solution Approach 2:
The patent ensures uniform TiC precipitation distribution throughout the entire steel coil cross-section and length by controlling the slow cooling rate. This creates local quality homogeneity in the precipitate distribution, preventing localized over-precipitation that would occur with faster cooling, thereby achieving high tensile strength without the harmful effects of non-uniform microstructure.
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 achieves a significant increase in yield and tensile strength of 10-40 MPa and 10-50 MPa respectively, while maintaining plasticity, by ensuring uniform TiC precipitation across the steel coil.
Implementation Method 1
the steel coil is insulated and slowly cooled
Implementation Method 2
promote uniform and full precipitation of TiC
Data Source
AI summary
There is provided a production method for on-line improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel, comprising: casting a molten steel with microalloying element Ti added to obtain an ingot; after heating the ingot, subjecting it to rough rolling, finish rolling, laminar cooling and coiling to obtain a hot-rolled coil; after unloading the coil, covering the coil on-line with an insulating enclosure and moving it into a steel coil warehouse along with a transport chain; after a specified period of on-line insulating time, removing the coil from the insulating enclosure, and cooling it to room temperature in air, wherein the microalloying element Ti has a content of ≥0.03 wt %; the coiling is performed at a temperature of 500-700° C.; said covering on-line with an insulating enclosure means each hot-rolled coil is individually covered with an independent, closed insulating enclosure unit within 60 minutes after unloading; the on-line insulating time is ≥60 minutes. The method of the present disclosure is characterized by low cost and high efficiency, and is not affected by surroundings.