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What issues should be noted when rolling stainless steel coils
source：www.cnlichao.net | Release time：2026年07月13日1、 Precautions for raw materials in the early stage
1. Composition and billet screening
Austenitic (304, 316L), ferritic, and duplex steel (2205) have significant differences in characteristics and cannot share a set of rolling parameters; Internal inclusions, subcutaneous bubbles, and compositional segregation in the billet will form elongated indentations and internal cracks after rolling; Raw materials entering the factory must undergo surface inspection to remove scars, deep scratches, and edge gaps from the raw materials.
2. Hot rolled billet pretreatment
Hot rolled billets must be descaling with high-pressure water; The oxide scale is not completely removed, resulting in the formation of pitting and black spots after rolling; Cold rolled raw materials need to be pickled to clean the surface oxide layer, otherwise it will scratch the roller surface and steel strip surface.
2、 Key control points for hot rolling and rolling
1. Temperature control (top priority)
(1) Heating temperature: The heating temperature of austenitic stainless steel slab should be controlled between 1100-1260 ℃ and should not exceed 1270 ℃; Excessive temperature leads to coarse grains and a sudden increase in oxide scale; Low temperature leads to poor plasticity and easy cracking at the edges; The furnace flame cannot directly spray the steel billet to avoid local overheating and carbonization defects; Reasonable insulation time to prevent overheating.
(2) Final rolling temperature: 304 final rolling temperature>920 ℃; Dual phase steel 2205 controls 1080-1120 ℃; The cooling speed of the edges is fast, and the edges and corners should be cooled first. It is necessary to open the insulation cover to reduce the temperature drop of the edges and prevent edge cracking; The side pressure of the precision rolling vertical roller should not be too large.
(3) Coiling temperature: ordinary austenitic steel coiling ≤ 600 ℃; Excessive coiling temperature can cause aging hardening, resulting in a significant increase in subsequent cold rolling force; The temperature is too low, and the residual stress inside the steel coil is too high, resulting in severe warping in the later stage.
2. Pressure distribution and rolling speed
（1) The deformation resistance of stainless steel is much higher than that of ordinary carbon steel, and excessive single pass compression is strictly prohibited; The rough rolling distribution has a reasonable reduction amount, and the rolling speed should be increased as much as possible to shorten the temperature drop;
(2) Enable AGC automatic thickness control system for online thickness measurement, with real-time monitoring of thickness at the head, tail, middle, and sides; Prevent issues such as excessive thickness tolerance, sickle bending, middle waves, and edge waves.
3. Requirements for hot rolling equipment
(1) The rolling mill is regularly ground, and there is no peeling or hard spots on the rolling surface; The rigidity of the rolling mill frame is sufficient to reduce equipment vibration;
(2) Export configuration CCD surface online detection, timely identification of scratches and indentation defects; The winding tension is stable to prevent interlayer slip and abrasion of the steel coil.
3、 Key points of cold rolling and rolling
1. Control of pass pressure reduction (core)
1. Austenitic stainless steel has extremely strong work hardening during cold rolling, and martensitic transformation occurs during 304 rolling, resulting in a rapid increase in hardness; The single pass compression rate is controlled at 10-15%, and the total compression rate is generally controlled at 50-80%; Excessive single pass compression results in micro cracks, edge cracks, and strip breaks in the steel strip; The pressure is too small and the production efficiency is low.
After the compression rate is too high, it is necessary to arrange intermediate annealing (solution treatment) to release internal stress, and then continue rolling after annealing; Otherwise, the subsequent stamping will crack and rebound severely.
3. For ultra-thin stainless steel (0.08-0.5mm), a 20 roll Sendzimir rolling mill is preferred, relying on a high stiffness rolling mill to ensure thickness accuracy.
2. Rolling tension control
1. The tension throughout the cold rolling process must be stable; The tension of thick material is relatively low, and the tension of thin steel strip is appropriately increased; If the tension fluctuation of ultra-thin strip steel is ± 2%, the thickness will be unqualified;
2. Excessive tension: longitudinal microcracks, wrinkling of the inner layer of the steel coil; Insufficient tension: steel strip shaking and deviation, wave appearance, and surface abrasion;
3. The surface of the guide roller and tension roller should be polished, and there should be no burrs on the roller surface to prevent horizontal scratches; The steel strip always runs in the center to avoid scratching the edges of the baffle.
3. Lubrication and cooling system (the most important in cold rolling)
1. Stainless steel special rolling oil must be used; Strictly control emulsion concentration, oil temperature, and cleanliness; Insufficient lubrication due to low oil concentration, resulting in blackening of the plate surface and sticking of steel to the rolling mill rolls; Excessive concentration of residual oil stains makes subsequent polishing and cleaning difficult.
2. Continuously rinse the roll gap with rolling oil to remove all fallen iron filings and powder; Equipped with a blowing device, debris is pressed into the steel strip to form periodic indentations; Mirror stainless steel requires higher purity of rolling oil, and the rolling oil should be filtered and replaced regularly.
3. Control the temperature rise during rolling: If the temperature rise during rolling friction is too high, it will cause uneven local martensite content, color difference on the plate surface, and inconsistent hardness.
4. Roll management
1. The roughness of the work roll can be set as needed: Ra0.4-0.6 μ m for ordinary industrial surfaces; Mirror roller Ra0.1-0.2 μ m; Wear and tear of the rolling mill, peeling of the rolling surface, and excessive ellipticity should be repaired immediately; Defects in the rolling mill will periodically print onto the steel strip;
2. Real time adjustment of bending rollers and running rollers to improve plate shape and control edge waves, medium waves, and 1/4 wave shapes.
4、 General precautions (applicable to both hot and cold rolling)
1. Plate shape and residual stress issues
After rolling, there are residual stresses inside the steel coil. If the rolling parameters are not reasonable, warping, arching, and buckling may occur after later flattening; Relying on bending rollers, segmented cooling, and reasonable tension to improve plate shape; After the finished roll, it is necessary to perform leveling and straightening.
2. Surface quality issues (stainless steel core assessment indicators)
Roll printing: damage to the rolling mill roll, sticking to the roll; Countermeasure: Regularly grind the rolling mill rolls;
Slip abrasion: unstable tension, inconsistent tension of steel coil;
Pit pressing: iron filings, dust, foreign hard particles; Do a good job of blowing and dust removal;
Color difference: uneven oxidation during hot rolling, uneven oil temperature during cold rolling, and unqualified annealing atmosphere;
Edge cracking: rapid cooling of hot-rolled edges, excessive cold rolling reduction, and excessive burrs on raw material edges; Hot rolling controls edge temperature drop, cold rolling controls single pass pressing, incoming burrs ≤ 0.05mm.
3. Classification and management of brand names
304、316L、 Rolling parameters for 430 ferrite and 2205 duplex steel cannot be mixed:
Ferritic stainless steel has low work hardening, and the single pass reduction can be appropriately increased;
Dual phase steel has poor plasticity, narrow rolling temperature window, small reduction, and slow rolling speed, otherwise it is prone to cracking.
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