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How to ensure the quality of stainless steel coils
source：www.cnlichao.net | Release time：2026年04月14日1、 Source material control: correct ingredients, casting essential quality
The modern smelting process of electric arc furnace, external refining, and vacuum degassing is adopted to strictly control the proportion of alloy elements such as chromium, nickel, molybdenum, manganese, and silicon, ensuring that the composition of various grades such as 304, 316L, and 2205 correctly meets the national standard requirements. The chromium content is stable to ensure the formation ability of passivation film, the molybdenum element strengthens the anti pitting performance, and the low-carbon design prevents intergranular corrosion risks.
Strictly control the content of harmful impurities such as phosphorus, sulfur, hydrogen, oxygen, and non-metallic inclusions throughout the process. Adopt technologies such as electric slag remelting and correct temperature control in continuous casting to achieve greater material purity and tissue uniformity, and eliminate inherent defects such as internal cracks, inclusions, and segregation from the root.
Each batch of steel coils is equipped with a three in one traceability system of furnace number, batch number, and melting number. The original factory issues a material certificate (MTC), which contains complete chemical composition and performance data, achieving quality traceability throughout the entire process.
2、 Rolling process control: precision forming to ensure dimensional accuracy
The hot rolling stage is centered around constant temperature rolling and controlled cooling processes to ensure uniform slab temperature, stable rolling pressure, effective control of flatness, and avoidance of defects such as edge cracking, wave shape, uneven thickness, and sickle bending.
Cold rolling adopts multi pass precision rolling and tension control technology to achieve micrometer level correct control of thickness, width, and unevenness. The dimensional tolerance strictly follows the national standard limit, and the thickness deviation and batch size fluctuation of the same coil are controlled within the allowable range of the standard.
The entire rolling process adopts online non-destructive testing and closed-loop automatic control, real-time monitoring of plate shape, surface, and size parameters to ensure stable and consistent geometric accuracy of each coil, laying a solid foundation for subsequent processing procedures such as opening, rounding, stamping, and welding.
3、 Heat treatment and surface control: optimizing organization and improving overall performance
Strictly implement the standard process of solid solution annealing+rapid cooling, eliminate internal stress during rolling through correct temperature control, insulation time and cooling rate control, achieve uniform metallographic structure, refine grain size, and ensure that the material has excellent plasticity, toughness and stable mechanical properties.
Equipped with environmentally friendly pickling and passivation treatment processes, the surface oxide scale, chromium poor layer, and residual impurities are removed, and the stainless steel passivation film is repaired and strengthened, significantly improving corrosion resistance and surface smoothness, and eliminating quality problems such as yellowing, rusting, and darkening of the surface.
Surface quality grading control is implemented, and different surface grades such as 2B, BA, and polished surfaces are inspected according to national standards. There are no scratches, roller marks, pits, dents, color differences, or rust, and the surface roughness is uniform and controllable, meeting the high standard requirements of post-treatment processes such as polishing, electroplating, and spraying.
4、 Mechanical performance control: meet performance standards and adapt to various working conditions
Carry out mechanical performance testing such as tensile testing, bending testing, hardness testing, and impact testing in accordance with national standards to ensure that yield strength, tensile strength, elongation, cold bending performance, and other indicators fully comply with the corresponding grade and usage standards.
For special scenarios such as pressure vessels and sanitary equipment, the performance requirements are tightened according to GB/T 24511 standard, supplemented with intergranular corrosion testing, pitting corrosion equivalent (PREN) testing, and salt spray testing to ensure the long-term stability and safety of materials in corrosive environments and pressure conditions.
Performance testing data is recorded throughout the process, double checked by two people, and non-conforming products are strictly isolated and disposed of to prevent substandard products from entering the market.
5、 Full process inspection and control: layered checks to ensure factory compliance
Establish a four level quality control system for raw material inspection, process inspection, finished product inspection, and factory re inspection, equipped with detection equipment such as direct reading spectrometer, ultrasonic flaw detector, laser leveling instrument, roughness meter, salt spray test box, etc., to achieve full parameter and multi-dimensional quality verification.
The inspection process strictly follows the national standard inspection rules, implements sampling standards, judgment criteria, and re inspection processes. Key items are 100% fully inspected, and general items are sampled proportionally to ensure that the quality of each coil meets the standards and customer requirements.
Before leaving the factory, complete surface, size, performance, labeling, and packaging inspections. Qualified products are labeled with qualified labels and standardized coding to ensure clear, correct, and traceable product information.
6、 Packaging, storage and transportation control: full protection throughout the process to prevent secondary damage
The finished steel coil adopts a standardized protection scheme of film covering, paper padding, moisture-proof packaging, and steel strapping. The packaging strength meets the requirements of long-distance transportation and long-term storage, effectively preventing secondary damage such as scratches, collisions, rain, moisture, and pollution during transportation.
The storage environment should be kept dry, ventilated, clean, and at a constant temperature, away from acids, alkalis, corrosive gases, and humid media. It should be stored by brand, specification, and furnace number to avoid mixing batches, mixing numbers, and physical damage.
The transportation process adopts professional logistics, standardized loading and unloading, eliminates rough operations, and ensures stable and intact quality of steel coils from factory to delivery.
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