Hot Rolling Temperature Offset for Residual-Element Steel Scrap
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Solution Overview
Problem
The use of steel scraps in steelmaking introduces significant amounts of residual elements like copper, chromium, molybdenum, nickel, tin, antimony, zinc, and arsenic, which negatively affect the hot rolling processability of semi-finished steel products, leading to processability issues and potential degradation of rolling cylinders.
Innovation Solution
A method is developed to adjust the hot rolling temperature by calculating a temperature increase (TOFFSET) based on the presence of residual elements (Mo, Sn, Sb, and As) to offset their impact on the mean flow stress, ensuring the targeted reduction rate is achieved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If steel scraps are used to reduce carbon footprint, then environmental sustainability is improved, but residual elements deteriorate hot rolling processability
Solution Approach 1:
The invention changes the hot rolling temperature parameter by defining an increased finishing temperature THR that compensates for the presence of residual elements. This parameter adjustment allows the steel to maintain adequate flow stress levels during hot rolling despite the detrimental effects of residual elements from steel scraps, thereby resolving the contradiction between using steel scraps for sustainability and maintaining processability.
2Productivity
If residual elements are present in steel composition, then steel scraps utilization is improved, but mean flow stress during hot rolling is adversely affected
Solution Approach 1:
The invention applies preliminary anti-action by pre-calculating the detrimental impact of residual elements on mean flow stress and compensating for it in advance through temperature adjustment. The increased finishing temperature THR is determined before hot rolling to counterbalance the flow stress reduction caused by residual elements, allowing high steel scraps utilization without compromising the mechanical behavior during deformation.
3Ease of manufacture
If hot rolling temperature is increased to compensate for residual elements, then processability is improved, but energy consumption increases
Solution Approach 1:
The invention applies partial action by increasing the hot rolling temperature only to the extent necessary to compensate for residual element effects, rather than using excessive temperature increases. The finishing temperature THR is precisely calculated to provide just enough compensation for the flow stress reduction, avoiding unnecessary energy consumption while still improving processability.
Data Source
AI summary
A method for hot rolling a steel including the steps of i. elaborating, by smelting steel scrap including at least one of the following residual elements: Mo, Sn, Sb, As, a steel grade having a theoretical hot rolling temperature THR_TH, by smelting steel scraps including at least one of the following residual elements: Mo, Sn, Sb, As, and optionally hot metal coming from a blast furnace and/or direct reduced iron, ii. estimating the liquid steel composition, iii. casting a semi-finished product with the liquid steel, iv. defining, TOFFSET, the smallest hot rolling temperature increase able to offset the presence of the residual elements: Mo, Sn, Sb and/or As, v. hot rolling the semi-finished product at a temperature THR being: THR=THR_TH+TOFFSET.