AHSS Scale Conditioning With Quasi-Molten Alkali Salt Pickling
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Solution Overview
Problem
Advanced high strength steels with high alloy percentages pose challenges in removing complex oxide scales formed during hot rolling, as conventional pickling processes are inefficient and can impact the steel surface, leading to residual oxides and reduced production throughput.
Innovation Solution
A method involving a first conditioning process that compromises the structural integrity of the iron oxide in the scale layer, followed by the application of an aqueous alkali salt solution heated to a quasi-molten form, which oxidizes the alloy oxides and forms water-soluble compounds, allowing for efficient removal of the scale through a final pickling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pickling processes are used to remove oxide scales from advanced high strength steels, then scale removal is achieved, but the process is inefficient and causes adverse effects on the steel surface
Solution Approach 1:
The patent applies preliminary conditioning treatments (mechanical, chemical, or thermal) to the oxide scale before the main pickling process. This preliminary action modifies the scale structure and composition, making it more susceptible to removal while reducing the aggressiveness needed in the subsequent pickling step, thereby protecting the steel surface from adverse effects.
Solution Approach 2:
The patent changes the parameters of the pickling process by using diluted acid solutions (1-10% concentration) compared to conventional concentrated acids, and by controlling temperature parameters (heating to 50-150°C). These parameter changes enable effective scale removal while minimizing harmful effects on the steel surface.
2Reliability
If conventional pickling processes are used to remove oxide scales, then scale removal is achieved, but production throughput is reduced
Solution Approach 1:
By applying preliminary conditioning treatments that compromise the structural integrity of the oxide scale, the main pickling process becomes faster and more efficient. This two-stage approach (conditioning + pickling) significantly reduces the total time required for scale removal compared to conventional single-stage pickling, thereby maintaining or even increasing production throughput.
Solution Approach 2:
The patent segments the scale removal process into distinct stages: preliminary conditioning (mechanical, chemical, or thermal treatment) and subsequent pickling. This segmentation allows each stage to be optimized independently, with the conditioning stage preparing the scale for faster removal and the pickling stage efficiently removing the compromised scale, improving overall productivity.
3Reliability
If conventional pickling processes are used on high alloy steels, then scale removal is attempted, but the process is inefficient due to complex oxide mixtures
Solution Approach 1:
The preliminary conditioning stage specifically targets the complex oxide scale structure formed on high alloy steels, using mechanical blasting, chemical treatment, or thermal processing to break down the refractory oxide mixtures. This preparation makes the subsequent pickling process much more efficient at removing the compromised scale, overcoming the inefficiencies of direct conventional pickling on complex oxide scales.
Solution Approach 2:
The patent uses diluted acid solutions (1-10% concentration) and controlled temperature parameters (50-150°C) that are specifically suited for treating complex oxide scales on high alloy steels. These parameter changes make the pickling process more efficient and controllable compared to conventional concentrated acid pickling, improving ease of manufacture while maintaining scale removal effectiveness.
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 approach effectively removes complex oxide scales from advanced high strength steels, ensuring a clean surface for subsequent processing and maintaining production throughput, while minimizing adverse effects on the steel surface.
Implementation Method 1
The disposed aqueous alkali salt solution is heated to at least 288 degrees Celsius (550 degrees Fahrenheit), the heating transforming one or more alkali salts within the disposed aqueous alkali salt solution into a quasi-molten form
Implementation Method 2
The alloy oxide is oxidized via reaction with the quasi molten form of the alkali salt(s) and with water within the disposed aqueous alkali salt solution, forming one or more water soluble alkali alloy compounds
Implementation Method 3
The surface of the advanced high strength steel product is rinsed with water, the water dissolving the water soluble alkali alloy compound(s) and rinsing the dissolved compound(s) from the surface
Data Source
AI summary
Aspects treat and remove a layer of scale comprising iron oxide and alloying elements oxides that is formed on an advanced high strength metal surface comprising at least two (2) percent by weight of alloy. A first conditioning process compromises structural integrity of or removes iron oxide within the scale layer to expose the alloy oxide to chemical engagement with a disposed aqueous alkali salt solution that is heated to transforming one or more alkali salts within the disposed solution into a quasi-molten form. The alloy oxide is oxidized via reaction with the solution quasi molten alkali salt(s) and water, forming one or more water soluble alkali alloy compounds. A water rinse dissolves and rinses the water soluble compound(s) from the steel product surface of the advanced high strength, leaving a film of iron oxide on the surface that is removed via a final pickling process.