What is the cold rolling process for stainless steel strip
source:
www.chengguosheying.com | Release time:2025年08月12日
The cold rolling process of stainless steel strip is the process of rolling and processing the hot-rolled stainless steel strip at room temperature to obtain higher dimensional accuracy, better surface quality, and specific mechanical properties. Its process is complex and requires strict equipment and operation. The specific process is as follows:
1、 Preparation process before cold rolling
Raw material selection and inspection
The raw material is usually hot-rolled stainless steel strip (thickness generally 3-12mm), which needs to meet the requirements of composition (such as 304, 316L, etc.) and surface quality, avoiding defects such as cracks and inclusions.
The inspection includes chemical composition analysis, mechanical property testing (such as hardness and tensile strength), and surface defect detection (such as oxide scale and scratches).
Raw material pretreatment
Acid washing: Remove the oxide scale on the surface of hot-rolled strip (such as Cr ? O ∝ formed by high-temperature rolling), commonly soaked or sprayed with mixed acid (nitric acid+hydrofluoric acid) to ensure good contact between the rolling mill and the strip during cold rolling and avoid indentation defects.
Edge trimming: Trim the edges of the strip with a disc cutter to remove burrs and cracked edges, ensuring uniform width and preventing edge tearing during rolling.
Degreasing: Clean the surface of the strip with alkaline solution or organic solvent to prevent oil stains (such as rolling oil residue) from contaminating the rolling mill rolls or affecting surface quality during cold rolling.
2、 Core process of cold rolling and rolling
Cold rolling involves multiple sets of rolling mills (usually reversible cold rolling mills or continuous cold rolling mills) to roll the strip multiple times, gradually reducing thickness and improving performance, divided into the following key steps:
Rolling parameter setting
According to the target thickness (cold-rolled strip thickness can be as thin as 0.01mm) and material characteristics (such as good ductility of austenitic stainless steel and high hardness of ferritic stainless steel), set the rolling force, rolling speed, and reduction amount (single rolling thickness reduction, usually 5% -30%).
For example, rolling 8mm hot-rolled strip to 1mm requires 5-8 passes of rolling, and the amount of reduction per pass gradually decreases as the strip becomes thinner.
Rolling process control
Roller configuration: The roller material is high hardness alloy (such as tungsten carbide coating), and the surface is precision ground (roughness Ra ≤ 0.02 μ m) to ensure a smooth surface of the strip.
Rolling oil lubrication and cooling: Spray rolling oil (containing mineral oil and additives) to reduce friction between the rolling mill and the strip, while cooling the rolling mill (preventing overheating and deformation) and the strip (avoiding excessive work hardening).
Tension control: Apply tension (longitudinal tension) through unwinding and coiling machines to ensure the flatness of the strip and reduce wave or sickle bending defects during rolling.
Multi pass rolling and intermediate annealing (optional)
For high reduction rolling (such as reducing thickness from 5mm to 0.5mm), the plasticity of the strip will decrease due to work hardening (grain deformation, increased hardness), and annealing treatment is required in the intermediate process:
Heating to 1050-1150 ℃ (austenitic stainless steel) in a protective atmosphere (such as nitrogen), rapid cooling after insulation, restoring material plasticity, and facilitating subsequent rolling.
After annealing, acid washing is required again to remove the oxide scale generated during annealing.
3、 Cold rolling post-treatment process
Precision rolling (finishing)
Perform slight rolling on cold-rolled products (with a reduction of 1% -3%) to eliminate minor surface defects (such as roll marks), adjust surface roughness (such as obtaining 2B, BA, and other surface smoothness), and stabilize strip size.
straightening
Use a multi roll straightening machine (such as a twenty roll straightening machine) to correct the flatness of the strip, eliminate bending and warping caused by rolling, and ensure that the flatness of the strip is ≤ 1mm/m.
Cutting and coiling
According to customer requirements, the wide strip is cut into narrow strips of different widths using a slitting machine, and then rolled into neat rolls (usually with an inner diameter of 508mm or 610mm) by a coiling machine.
test
Check the dimensional accuracy (thickness tolerance ± 0.01mm, width tolerance ± 0.1mm), surface quality (no scratches or pitting), mechanical properties (hardness, elongation), and package and store after passing the inspection.