Thin-Gauge Checkered Steel Composition for Strength and Formability
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Solution Overview
Problem
The production of high-strength, thin-gauge checkered steel plates is challenging due to issues such as nonuniform structure, low elongation, high yield ratio, and poor formability, particularly in the thin strip continuous casting process, which also faces difficulties in controlling oxide scale thickness and surface quality, leading to increased production costs and market demand for such products.
Innovation Solution
A twin-roll thin strip continuous casting process is employed, utilizing residual elements like Sn and Cu from steel scrap as alloy elements, with controlled smelting conditions and gas atomization cooling to produce a high-strength thin-gauge checkered steel plate/strip, featuring a mixed microstructure of acicular ferrite+pearlite, and a composition optimized for strength and surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional multi-pass continuous rolling is used to produce thin strip steel, then the production process is complex with high energy consumption, but the product thickness can be reduced to ≤1.5 mm
Solution Approach 1:
The patent merges continuous casting and continuous rolling into an integrated thin slab continuous casting and rolling process. The casting and rolling operations are combined in a single continuous flow, eliminating the need for separate reheating and multi-pass rolling operations, thus simplifying the production process while maintaining thin gauge capability
Solution Approach 2:
The patent implements a continuous casting and rolling process where the slab is cast and rolled in one continuous operation without interruption. The thin slab exits the caster and enters the rolling mill immediately, maintaining continuous material flow and eliminating idle time between operations
2Loss of energy
If thin slab continuous casting and rolling is used to shorten process flow, then energy consumption is reduced, but the steel strength and yield ratio increase causing high rolling load
Solution Approach 1:
The patent changes the chemical composition parameters of the steel to optimize the balance between strength and formability. By controlling carbon content at ≤0.06%, adding specific amounts of Mn (0.4-1.7%), Si (0.1-0.5%), and micro-alloying with B (0.001-0.006%) and Ti (0.001-0.005%), the steel achieves adequate strength while maintaining lower yield ratio and improved elongation, thus reducing rolling load
3Reliability
If residual elements Sn and Cu are removed from steel scrap, then the steel quality is improved, but the smelting cost increases
Solution Approach 1:
The patent converts the harmful residual elements Sn and Cu into beneficial alloying elements. By controlling Sn at 0.005-0.04% and Cu at 0.1-0.6%, these elements are retained in the steel to provide solid solution strengthening and improve mechanical properties, eliminating the need for expensive removal processes while maintaining steel quality
Solution Approach 2:
The patent changes the acceptable concentration parameters for Sn and Cu from trace levels to controlled alloying levels. This parameter change transforms these elements from harmful impurities to useful alloying elements, allowing their retention in the steel without compromising quality while reducing smelting costs
4Loss of energy
If twin-roll thin strip continuous casting is used to produce thin strip, then production cost is reduced, but the surface quality and oxide scale control become difficult
Solution Approach 1:
The patent employs an inert or controlled atmosphere environment during the casting and rolling operations to prevent excessive oxide formation on the strip surface. By controlling the atmospheric conditions, oxide scale thickness is minimized and surface quality is maintained despite the simplified twin-roll process
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 process achieves high yield strength, tensile strength, and elongation, while significantly reducing production costs and improving surface quality, enabling direct marketing of the steel plates/strip for various applications.
Implementation Method 1
two counter-rotating crystallization rolls capable of rapid cooling. The molten steel solidifies on the circumferential surfaces of the rotating crystallization rolls
Implementation Method 2
The rolled strip steel is cooled by gas atomization cooling
Data Source
AI summary
Provided are a high-strength thin-gauge checkered steel plate/strip comprising the following chemical elements in weight percentages: C: ≤0.06%, Si: ≤0.5%, Mn: 0.4-1.7%, P≤0.04%, S≤0.007%, N: 0.004-0.010%, Als: <0.001%, B: 0.001-0.006%, Mn/S≥250, total oxygen [O]T: 0.007-0.020%; Cu: 0.1-0.6% and/or Sn: 0.005-0.04%; and a balance of Fe and other unavoidable impurities, and a manufacturing method thereof. The resultant steel roll can be used directly as hot-rolled checkered plate/strip, or as a finished checkered plate/strip after being cut and finished, and is widely applicable to the fields of architecture, mechanical production, automobile, bridges, transportation, ship building, etc.