Ultra-Thin Hot-Rolled Strip from Scrap Steel Without Pre-Sorting

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Solution Overview

Problem

Traditional hot-rolled strip steel production processes are complex, costly, and inefficient, particularly due to the need for pre-screening and special treatments of scrap steel to control harmful elements, which increases production costs and reduces steel quality.

Innovation Solution

A compact short-flow process using induction electric furnace technology and twin-roll thin strip continuous casting to produce ultra-thin hot-rolled strip steel from 100% scrap steel, integrating smelting, continuous casting, and rolling, with rapid solidification and atomization cooling to eliminate grain boundary segregation and enhance steel properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional continuous casting and rolling processes are used with thick slabs, then production cost and equipment complexity are reduced, but the solidification cooling rate is too slow (10-1°C/s) causing grain boundary segregation and poor steel quality

Engineering Contradiction:
Improvesteel qualityVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent divides the traditional thick slab casting process into thin strip continuous casting with much finer segmentation of the solidification process, achieving a cooling rate of 100-1000°C/s through specialized thin strip casting equipment. This segmentation allows precise control of solidification to eliminate grain boundary segregation while maintaining process feasibility

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent fundamentally changes the solidification parameters by reducing strip thickness to enable rapid cooling. By changing from thick slab (150mm+) to thin strip geometry, the surface area to volume ratio increases dramatically, enabling cooling rates of 100-1000°C/s versus the traditional 10-1°C/s, thereby eliminating grain boundary segregation and improving steel quality

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If pre-screening and special treatments of scrap steel are implemented to control harmful elements, then steel quality is improved, but production cost increases

Engineering Contradiction:
Improvesteel qualityVSAvoidproduction cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent converts harmful elements in scrap steel into beneficial solid solution strengtheners. Rather than expensively removing harmful elements through pre-screening and special treatments, the rapid solidification process traps these elements in solid solution form, where they strengthen the steel matrix. This approach transforms a quality problem into a strengthening mechanism, eliminating the need for costly preprocessing while improving both quality and cost-effectiveness

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Manufacturing precision

If thin strip continuous casting with rapid solidification is used, then grain boundary segregation is eliminated and steel quality is improved, but equipment complexity and investment cost increase

Engineering Contradiction:
Improvesteel qualityVSAvoidequipment complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the continuous casting and rolling processes into an integrated thin strip continuous casting-rolling system. By combining these operations and implementing inline hot rolling immediately after casting, the system achieves rapid solidification (100-1000°C/s) while eliminating the need for separate preprocessing and treatment equipment. This integration reduces overall equipment complexity and investment cost compared to traditional separate processes

Inventive Principle:
Principle #5Merging (Combining)

4Ease of manufacture

If all-waste grade scrap steel is used without pre-screening, then production cost is reduced and environmental friendliness is improved, but harmful elements may degrade steel quality

Engineering Contradiction:
Improveproduction costVSAvoidsteel quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent uses parameter changes in the solidification process (rapid cooling at 100-1000°C/s) to overcome the quality issues of using all-waste grade scrap steel. The rapid solidification kinetics prevent harmful elements from forming detrimental phases or segregating, instead trapping them in solid solution where they strengthen the matrix. This parameter change allows unrestricted use of scrap steel while maintaining or improving quality

Inventive Principle:
Principle #35Parameter changes

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 results in a cost-effective, environmentally friendly, and high-quality ultra-thin hot-rolled strip steel with improved mechanical properties, utilizing harmful elements as solid solution strengtheners and reducing carbon emissions.

Implementation Method 1

The present disclosure utilizes the induction electric furnace technology

Methodology Applied
Scientific EffectElectromagnetic induction heating: Electromagnetic Induction

Implementation Method 2

induction electric furnace technology is utilized to realize 100% scrap steel smelting

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 3

the twin-roll thin strip continuous casting technology is utilized to realize the production of ultra-thin hot-rolled strip steel from inferior scrap steel resources; the molten metal is directly cast into a thin gauge of 1.6-2.5 mm strip blank

Methodology Applied
Scientific EffectRapid solidification: Crystallisation

Implementation Method 4

twin-roll thin strip continuous casting to produce ultra-thin hot-rolled strip steel from 100% scrap steel, integrating smelting, continuous casting, and rolling, with rapid solidification and atomization cooling

Methodology Applied
Scientific EffectContact cooling: Cooling

Implementation Method 5

with rapid solidification and atomization cooling to eliminate grain boundary segregation and enhance steel properties

Methodology Applied
Scientific EffectAtomization cooling: Cooling

Data Source

PatentEP3851216B1Method for producing ultra-thin hot-rolled strip steel
Publication Date: 2023.07.26 BAOSHAN IRON & STEEL CO LTD
  • EP3851216B1 patent drawingFigure 1

AI summary

A method for producing ultra-thin hot-rolled strip steel, the method comprising the following process steps: A. a smelting process: feeding scrap steel into an induction electric furnace (1) for smelting so that the scrap steel melts into molten steel; B. a refining process: using a ladle refining furnace (2) and a ladle vacuum degassing furnace (3) to refine the molten steel; C. a continuous casting process: casting the refined molten steel into a cast strip blank that has a thickness of 1.6-2.5mm by means of a dual-roller thin strip continuous casting system (4); D. a hot rolling process: directly feeding the cast strip blank that was cast in the continuous casting process to a single-stand hot rolling mill (9) for rolling to produce hot-rolled strip steel, the thickness of the hot-rolled strip steel being 0.8-1.5mm; E. a cooling coiling process: performing atomizing cooling on the hot-rolled strip steel, and coiling after the strip steel temperature is controlled to be 400-750°C. The present method achieves an extremely compact, environmentally-friendly and economical ultra-thin hot-rolled strip steel production process flow, and achieves the environmentally-friendly and economical continuous production of metal plates and strips.