Ferritic Stainless Steel Composition for Crack-Resistant Clad Sheets
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Solution Overview
Problem
Ferritic stainless steel clad plates face issues with processing cracks and bends due to differences in material properties, necessitating the development of a material with superior clad plate workability.
Innovation Solution
A ferritic stainless steel with optimized alloy composition (0.0005-0.02% C, 0.005-0.02% N, 0.01-1.0% Si, 0.01-1.0% Mn, 0.001-0.05% P, 10.0-25.0% Cr, 0.01-0.5% Nb, 0.01-0.5% Ti) and a manufacturing process involving continuous casting, hot-rolling, hot rolling annealing, and final cold rolling annealing to achieve an average R-bar value of at least 1.5 and bend heights of 25 μm or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ferritic stainless steel is used for cooking utensils, then cost is reduced and surface quality is improved, but weight increases and heat conductivity decreases
Solution Approach 1:
The patent applies composite material structure by cladding ferritic stainless steel with aluminum or copper layers. The ferritic stainless steel base provides cost-effectiveness and surface quality, while the aluminum or copper cladding layers provide reduced weight and enhanced heat conductivity, creating a multi-layer composite cooking utensil that combines advantages of different materials
2Weight of moving object
If ferritic stainless steel is clad with Al or Cu, then weight is reduced and heat conductivity is improved, but processing cracks and bends occur due to different physical properties
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of ferritic stainless steel (C: 0.0005-0.02%, Si: 0.01-1.0%, Mn: 0.01-1.0%, Cr: 10.0-25.0%, Nb: 0.01-0.5%, Ti: 0.01-0.5%) and processing parameters (hot rolling temperature: 800-1250°C, hot rolling annealing: 900-1050°C, cold rolling reduction: ≥70%, final cold rolling annealing: 800-950°C for <1 hour). These parameter optimizations adjust the physical properties of ferritic stainless steel to better match the cladding material, reducing differential stress and preventing processing cracks and bends
Solution Approach 2:
The patent applies preliminary action by performing hot rolling and hot rolling annealing before cold rolling to pre-establish the microstructure and mechanical properties of ferritic stainless steel. The hot rolling process creates a controlled grain structure, and the subsequent cold rolling with ≥70% reduction followed by final annealing further refines the microstructure before cladding, ensuring the base material is in an optimal state to withstand cladding processing without cracking or bending
3Manufacturing precision
If cold rolling reduction rate is increased, then material density is improved, but processing complexity and time increase
Solution Approach 1:
The patent applies preliminary action by performing hot rolling and hot rolling annealing before cold rolling to pre-establish the microstructure and mechanical properties of ferritic stainless steel. This preliminary heat treatment and rolling process prepares the material to better withstand the high reduction rate cold rolling, enabling achieving ≥70% reduction without excessive processing time or complexity
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 solution enables the production of ferritic stainless steel with superior clad plate workability, reducing the occurrence of cracks and bends, and maintaining a hardness difference of 50 to 150 Hv for improved processing outcomes.
Implementation Method 1
hot-rolling the manufactured slab at a range of 800 to 1250° C.
Implementation Method 2
performing hot rolling annealing at a temperature range of 900 to 1050° C.
Implementation Method 3
performing final cold rolling annealing at a temperature range of 800 to 950° C. for less than 1 hour
Data Source
AI summary
The present invention relates to a ferritic stainless steel with excellent clad sheet workability, comprising: by wt %, 0.0005-0.02% of C, 0.005-0.02% of N, 0.01-1.0% of Si, 0.01-1.0% of Mn, 0.001-0.05% of P, 10.0-25.0% of Cr, 0.01-0.5% of Nb, 0.01-0.5% of Ti, and the balance of Fe and inevitable impurities, having an average R-bar value of R values for respective directions is at least 1.5, and having a roughness height after sheet cladding of 25 μm or less. In addition, the present invention relates to a method of manufacturing a ferritic stainless steel. The process involves continuous casting to create a slab with the specified composition, followed by hot rolling at 800-1250° C.; hot annealing same at 900-1050° C., and then cold rolling same with a reduction ratio of 70% or more; and performing final cold annealing at a temperature of 800-950° C. for less than 1 hour.