Ultra-Thin Hot-Rolled Strip Production With Scale-Controlled Heating
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Solution Overview
Problem
Current methods for producing hot-rolled steel strips are limited by a minimum thickness of 0.6 mm and require intermediate processing steps like pickling for corrosion protection, which increases costs and energy consumption, and are not suitable for producing ultra-thin strips below 0.6 mm without significant scale formation and cooling issues.
Innovation Solution
A continuous production process that includes initial thermal conditioning and descaling with an induction edge heater and water descaler, followed by controlled roughing and finishing rolling with protective atmospheres to minimize scale formation and allow direct corrosion coating without intermediate treatments, using a compact initial section and adjustable heating systems to maintain high temperatures and reduce oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional hot-rolling methods are used to produce thin steel strips, then production process is simple, but minimum thickness is limited to 0.6 mm and scale formation is excessive
Solution Approach 1:
The patent changes the temperature parameter throughout the rolling process, maintaining high temperatures (above 820-850°C at finishing mill exit) to keep steel in austenitic range, enabling ultra-thin strip production while controlling scale formation through controlled cooling rates and protective atmospheres
Solution Approach 2:
The patent introduces protective atmospheres (nitrogen or controlled oxygen content below 5%) in the rolling mill to prevent oxidation and scale formation on the steel strip surface during the rolling process, enabling direct coating without pickling
2Object-generated harmful factors
If induction heating is used to reduce scale formation, then scale is reduced, but energy consumption increases
Solution Approach 1:
The patent applies preliminary heating in the ingot mould during continuous casting to achieve uniform temperature distribution before rolling, reducing the need for additional induction heating and thereby lowering energy consumption while maintaining scale control
Solution Approach 2:
The patent maintains continuous high-temperature rolling without intermediate cooling and reheating cycles, keeping the steel in austenitic range throughout the process, which reduces total energy consumption compared to intermittent heating methods
3Object-generated harmful factors
If minimum dwell time at temperature is used to reduce scale, then scale formation is reduced, but temperature control flexibility is limited
Solution Approach 1:
The patent dynamically adjusts the dwelling time at temperature based on strip thickness requirements, allowing flexible control from ultra-thin (0.3 mm) to thicker strips while maintaining scale control through optimized cooling rates and protective atmospheres throughout the varying process conditions
4Object-generated harmful factors
If protective atmosphere is used in rolling mill, then scale formation is minimized, but device complexity increases
Solution Approach 1:
The patent uses the rolling mill atmosphere system for multiple purposes: controlling scale formation during rolling, maintaining austenitic temperature range, and preparing the strip surface for direct coating, thereby managing complexity through multi-functionality rather than separate systems
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
Enables the production of hot-rolled steel strips down to 0.3 mm thickness with reduced scale formation, minimizing energy consumption and production costs, and allowing direct corrosion coating without preliminary surface conditioning, enhancing plant compactness and energy efficiency.
Implementation Method 1
an induction edge heater (4.1) for heating the edges of the slab
Implementation Method 2
an induction heater (4.2) for heating the surface of the slab
Implementation Method 3
a water descaler (5.2) for removing the scale from the surface of the slab
Implementation Method 4
a protective atmosphere that prevents oxidation of the transfer bar being substantially composed of inert gas (nitrogen) with a minimum presence of oxygen (about 5% or less)
Data Source
AI summary
A plant and process for the continuous production of hot-rolled steel strips with a minimum thickness of 0.3 mm is disclosed which includes a continuous casting device of thin or medium slabs with a thickness between 40 and 150 mm and a maximum width of at least 2100 mm followed by a roughing mill, a first induction furnace, a water descaler, a second induction furnace, a finishing mill, a cooling station, a cutting station and a winding station. A system for feeding a protective atmosphere containing ≤3% vol. oxygen is provided from the inlet of the second induction furnace to at least the third stand of the finishing mill. Between the continuous casting device and the roughing mill, an initial thermal conditioning and descaling section is provided having in sequence an induction edge heater, an induction heater for the rest of the slab surface and a water descaler.