فولاد ضد زنگ درجه غذا چیست?

1. مقدمه

Food-grade stainless steel is a critical material in the food and beverage industry, valued for its exceptional combination of hygiene, مقاومت در برابر خوردگی, و دوام.

It endures high-temperature cleaning cycles and offers a smooth, non-porous surface that deters bacterial growth.

It plays a central role in every stage of food handling—from processing and preparation to storage and service.

Used extensively across domestic kitchens, commercial catering, سیستم لوله کشی, fermentation tanks, pharmaceutical facilities, and industrial food processing plants, food-grade stainless steel has become the industry standard where cleanliness and material integrity are non-negotiable.

2. What is Food-Grade Stainless Steel

Food-grade فولاد ضد زنگ is a type of stainless steel that has been specifically engineered and certified to meet strict safety and hygiene standards for use in direct contact with food.

Unlike general-purpose stainless steel, food-grade stainless steel is designed to prevent the leaching of harmful substances into food, resist corrosion from food acids and cleaning agents,

and be easily cleaned and sanitized to prevent the growth of bacteria and other pathogens.

It provides a reliable and durable surface that can withstand the rigors of food-related environments without compromising the safety or quality of the food it comes in contact with.

3. Common Food-Grade Stainless Steel Grades

Several grades of stainless steel meet food-grade requirements, each offering specific advantages depending on the intended application, exposure environment, and regulatory context.

عتیقه 304 (ایالات متحده S30400) – The Industry Standard

• ترکیب: ~18% Chromium, ~8% Nickel, ≤0.08% Carbon
• ساختار: وابسته به اوستن
• خصوصیات کلیدی:

• • Excellent corrosion resistance in normal atmospheric and mildly acidic food environments
  • غیر مغناطیسی در شرایط آنیل شده
  • Easily formed, جوش داده شده, and cleaned

• برنامه های مشترک:
  تجهیزات آشپزخانه, تانک های دم کرده, fermentation vessels, غرق, work surfaces, milk tanks

عتیقه 316 (S31600 ایالات متحده) – Enhanced Corrosion Resistance

• ترکیب: ~16% Chromium, ~10% Nickel, ~2% Molybdenum, ≤0.08% Carbon
• ساختار: وابسته به اوستن
• خصوصیات کلیدی:

• • Superior resistance to chloride-induced pitting and crevice corrosion
  • Performs well in acidic and salty environments (به عنوان مثال, سرکه, مرکب, آبسری)
  • Maintains strength and corrosion resistance at high temperatures

• برنامه های مشترک:
  Seafood processing, salt-rich or acid-rich food systems, medical food-contact components, commercial dishwashers

AISI 316L (S31603 ایالات متحده) – Low Carbon Variant

• ترکیب: شبیه 316 with ≤0.03% Carbon
• ساختار: وابسته به اوستن
• خصوصیات کلیدی:

• • Better resistance to intergranular corrosion after welding
  • Ideal for pharmaceutical and high-purity food systems requiring frequent cleaning (CIP/SIP)

• برنامه های مشترک:
  Bioreactors, clean-in-place systems, sterile food production equipment

عتیقه 430 (UNS S43000) – Ferritic, Cost-Effective Option

• ترکیب: ~16-18% Chromium, very low Nickel content
• ساختار: وابسته به فری
• خصوصیات کلیدی:

• • مغناطیسی, good corrosion resistance in dry environments
  • Lower cost due to minimal nickel
  • Less formable than 304 وت 316

• برنامه های مشترک:
  Food-grade countertops, display cabinets, back panels of appliances, low-risk dry food storage

عتیقه 201 (UNS S20100) – Low-Nickel Austenitic Alternative

• ترکیب: ~16-18% Chromium, ~3.5-5.5% Nickel, ~5.5-7.5% Manganese
• ساختار: وابسته به اوستن
• خصوصیات کلیدی:

• • هزینه کمتری, خصوصیات مکانیکی خوب
  • مقاومت در برابر خوردگی پایین, particularly to chlorides

• برنامه های مشترک:
  Trays, kitchen shelving, structural components not in direct food contact

4. Key Properties of Food-Grade Stainless Steel

Food-grade stainless steel owes its popularity in the food industry to a unique combination of material properties that meet stringent safety, عمل, and hygiene demands.

مقاومت در برابر خوردگی

One of the defining attributes of food-grade stainless steel is its excellent corrosion resistance.

This is primarily due to the formation of a stable, self-healing passive chromium oxide layer در سطح فولاد, which protects it from rust and chemical attack.

• 304 فولاد ضد زنگ performs reliably in general food environments, resisting acids found in dairy, میوه, and vegetables.
• 316 فولاد ضد زنگ, با مولیبدن اضافه شده (2 ~ 2 ٪), پیشنهاد superior resistance to chlorides and acids, making it suitable for marine foods, citrus products, and pickled items.
• در acidic or saline processing lines, the wrong grade can corrode and compromise food safety.

بهداشت و پاکسازی

A hygienic surface is essential for preventing microbial contamination in food processing.

• فولاد ضد زنگ است غیر متخلخ, meaning it doesn’t absorb food particles or bacteria.
• Grades with smoother finishes (like 2B or electropolished) are less likely to harbor microorganisms.
• It resists biofilm formation, especially when properly cleaned and maintained.

دوام

Food-grade stainless steels are exceptionally durable, able to withstand:

• سایش مکانیکی from chopping, اختلاط, or scraping
• دوچرخه سواری حرارتی in cooking, chilling, or steam cleaning
• Repeated cleaning with caustic and acidic agents

مقاومت دما

Food-grade stainless steel can maintain their mechanical properties across a wide temperature range:

• 304 وت 316 are stable up to 870درجه سانتیگراد (1600° F) in intermittent service and 925درجه سانتیگراد (1700° F) در خدمات مداوم.
• Stainless steel is ideal for both شرایط کرایوژنیک (به عنوان مثال, cold storage at-80°C) وت محیط های گرمای بالا like grills or autoclaves.

Non-Reactivity

Stainless steel does not leach harmful chemicals into food, making it a safe, مواد بی جان.

• Unlike aluminum or copper, من does not react with acidic foods like tomatoes, سرکه, or wine.
• This property protects both the integrity of the food product و equipment itself from degradation.

5. فرآیندهای تولیدی

ذوب و آلیاژ

The production of food-grade stainless steel begins with the melting of raw materials, which typically include iron ore, کروم, نیکل, and other alloying elements.

These materials are melted in electric arc furnaces or induction furnaces at high temperatures.

During the melting process, the alloying elements are carefully added in precise proportions to achieve the desired chemical composition.

The molten metal is then refined to remove impurities such as sulfur, فسفر, و گازها, ensuring the purity and quality of the stainless steel.

ریخته گری

Once the molten stainless steel has been properly alloyed and refined, it is cast into various forms such as ingots, لایحه, or slabs.

Continuous casting is a common method used, where the molten steel is poured into a water-cooled mold and solidifies as it is continuously withdrawn.

This process produces a uniform and high-quality casting that can be further processed into different products.

گرم و سرد کار

The cast stainless steel is then subjected to hot-working processes such as rolling, جعل, and extrusion at high temperatures.

Hot-working helps to shape the steel, refine its grain structure, and improve its mechanical properties.

After hot-working, the steel may undergo cold-working processes such as cold rolling, نقاشی, or stamping at room temperature.

Cold-working further enhances the strength and hardness of the steel while also allowing for the production of complex shapes and precise dimensions.

عملیات حرارتی

Heat treatment is an important step in the manufacturing of food-grade stainless steel to optimize its properties.

Processes such as annealing, فروکش, and tempering are used to relieve internal stresses, improve the microstructure, and enhance the corrosion resistance and mechanical properties of the steel.

به عنوان مثال, annealing involves heating the stainless steel to a specific temperature and then slowly cooling it, which softens the steel and improves its ductility.

تکمیل سطح

Food-grade stainless steel undergoes various surface-finishing processes to achieve the desired appearance and performance.

Common surface finishes include صیقل, brushing, وت برق. صیقل دادن یک صاف ایجاد می کند, shiny surface that is not only aesthetically pleasing but also easier to clean.

Brushing gives the steel a textured, matte appearance and can help to hide minor scratches.

Electropolishing is a more advanced process that uses an electrochemical reaction to remove a thin layer of the metal surface, resulting in a highly smooth and corrosion-resistant finish.

6. پایان سطح & پاککاری

In food-grade stainless steel applications, surface finish is not merely an aesthetic consideration—it is a functional requirement directly tied to hygiene, پاککاری, و مقاومت در برابر خوردگی.

A properly finished stainless steel surface minimizes bacterial adhesion, resists contamination, and facilitates effective cleaning and sanitation protocols.

Importance of Smoothness in Hygiene

A key factor in ensuring hygienic performance is زبری سطح, typically quantified by the Ra value (arithmetic average of surface irregularities, measured in micrometers or microinches).

• سطوح خشن (higher Ra values) can harbor میکروارگانیسم ها, food particles, and cleaning chemical residues, making them difficult to sanitize.
• سطوح صاف (lower Ra values) reduce biofilm formation and enhance پاککاری, especially in food, نوشیدنی, لبنیات, و صنایع دارویی.

Common Surface Finishes for Food-Grade Stainless Steel

Surface Treatments for Cleanability

In addition to mechanical and electrochemical finishing, surface conditioning treatments are often employed to enhance performance:

• انفعال: Involves treating the surface with nitric or citric acid to remove free iron and promote the formation of a stable chromium oxide layer, بهبود مقاومت در برابر خوردگی.
• انفجار مهره: A method of creating uniform matte finishes using fine glass or ceramic beads; هر چند, not ideal for hygienic zones due to higher Ra values unless followed by polishing.
• ترشی: Acid treatment that removes scale and discoloration from heat-affected zones; typically used after welding or hot-working.

7. Regulatory Standards & مجوزها

• FDA CFR Title 21: Stainless steel is an approved indirect food additive for food contact.
• NSF/ANSI 51: Defines stainless material suitability for food-prep surfaces.
• ISO 22000 / HACCP: Ensures materials support hazard prevention in food systems.
• اتحادیه اروپا 1935/2004: Allows stainless for European food contact.
• Finish Requirements: For critical food or pharmaceutical use, مشخص کنید electropolished or No. 4 پایان با ra 0.8 μM, and ensure post-fabrication انفعال is performed for maximum corrosion resistance.

8. Advantages of Food-Grade Stainless Steel

• مقاومت در برابر خوردگی استثنایی
  Resists oxidation and corrosion from food acids, رطوبت, and cleaning chemicals, ensuring longevity and maintaining food safety.
• Hygienic and Easy to Clean
  صاف, non-porous surfaces prevent bacterial growth and biofilm formation; compatible with rigorous cleaning and sanitation protocols including CIP and SIP.
• Durability and Mechanical Strength
  High tensile strength and impact resistance enable it to withstand mechanical stresses, دوچرخه سواری حرارتی, and heavy use in food processing environments.
• Non-Reactive and Food Safe
  Does not leach harmful substances or impart flavors, preserving the quality and safety of food products.
• مقاومت دما
  Maintains structural integrity under extreme temperatures, from freezing to high-heat cooking or sterilization processes.
• جذابیت زیبایی
  Attractive finish options (صیقلی, قلم مو, برقی شده) support both functional hygiene and visual standards in foodservice and retail environments.
• پایداری و بازیافت
  Fully recyclable material, supporting environmental sustainability efforts in food manufacturing and equipment industries.
• Compliance with Regulatory Standards
  Meets stringent certifications from FDA, NSF, and international food safety authorities ensuring reliable performance in food contact applications.
• تطبیق پذیری در برنامه ها
  Suitable for a wide range of equipment—kitchenware, مخازن ذخیره سازی, حامل, pharmaceutical vessels—offering adaptability across the food and beverage industry.

9. Limitations of Food-Grade Stainless Steel

• هزینه اولیه بالاتر
  Compared to other materials like plastics or carbon steel, food-grade stainless steel generally has a higher upfront purchase price.
• Susceptibility to Chloride-Induced Corrosion
  نمرات مانند 304 stainless steel can suffer pitting and crevice corrosion in high-chloride environments (به عنوان مثال, آب شور, برین) unless higher grades like 316 استفاده می شود.
• Work Hardening Challenges
  Stainless steel tends to harden during machining and forming, which can complicate fabrication and require specialized tooling or annealing steps.
• وزن
  Stainless steel is heavier than alternative materials such as aluminum or certain plastics, potentially limiting its use in weight-sensitive applications.
• Surface Damage Risk
  Although corrosion-resistant, scratches or surface damage can compromise the passive oxide layer, making localized corrosion or staining more likely.
• Limited Heat Conductivity
  Stainless steel has relatively low thermal conductivity, which may affect heat transfer efficiency in some cooking or processing equipment.
• Difficult Repairs and Modifications
  Welding and repairing stainless steel require skilled labor and proper procedures to avoid issues like sensitization or reduced corrosion resistance.
• Potential for Nickel Allergies
  Some individuals may have sensitivities to nickel present in stainless steel alloys, though the risk is generally low in typical food contact scenarios.

10. Applications of Food-Grade Stainless Steel

• Commercial Kitchens: غرق, prep counters, یخچال, لوازم.
• غذا & پردازش نوشیدنی: مخازن, لوله کشی, conveyors in dairy, آبجو, meat industries.
• داروخانه & Nutraceutical Production: راکتور, اتاق های تمیز, sterile conveying.
• Storage & Handling: Silos, bins, clean vessels.
• Special Environments: Cleanrooms, high-humidity zones, brine or high-acid facilities.

11. How to Clean Stainless Steel?

Maintaining the cleanliness and appearance of food-grade stainless steel is critical not only for aesthetic reasons but also to preserve its corrosion resistance and hygienic properties.

Proper cleaning protocols ensure the surface remains free from contaminants, prevents bacterial growth, and extends the material’s service life.

General Cleaning Principles

• Use Non-Abrasive Materials:
  Always clean stainless steel surfaces with soft cloths, sponges, or non-abrasive pads to avoid scratching the surface.
  Avoid steel wool or harsh brushes which can damage the protective chromium oxide layer.
• Mild Detergents:
  Use neutral pH detergents or soaps that effectively remove grease, روغن, and dirt without attacking the stainless steel surface.
  Avoid cleaners containing chlorine bleach or harsh acids unless specifically designed for stainless steel.
• Rinse Thoroughly:
  بعد از تمیز کردن, rinse the surface thoroughly with clean water to remove any detergent residues, which can cause spotting or corrosion if left behind.
• Dry Completely:
  Wipe the surface dry with a clean microfiber cloth to prevent water spots and mineral deposits, especially in hard water areas.

Cleaning Agents and Their Compatibility

• Alkaline Cleaners:
  Alkaline-based detergents, such as those containing sodium hydroxide or potassium hydroxide, are effective in removing organic residues, fats, و روغن.
  They are commonly used in industrial cleaning but should be used at recommended concentrations to avoid etching.
• Acidic Cleaners:
  Mild acidic cleaners (اسید فسفریک, اسید سیتریک) can be used to remove mineral deposits or rust stains.
  Strong acids (وابسته به هیدروکلریک, وابسته به گوگرد) should be avoided as they may damage the stainless steel unless properly diluted and controlled.
• Chloride-Free Formulations:
  Chlorides can cause pitting corrosion in stainless steel, especially in grades like 304. Always use chloride-free cleaning products to preserve corrosion resistance.

Cleaning Procedures for Specific Contaminants

• Fingerprints and Smudges:
  Use warm water with mild detergent followed by a soft cloth. For stubborn marks, diluted vinegar or specialized stainless steel cleaners can be used.
• Grease and Oil:
  Use alkaline detergents or degreasers designed for stainless steel. Avoid prolonged exposure to strong solvents.
• Rust Stains:
  Occasional surface rust can occur due to contamination from external sources (به عنوان مثال, iron particles).
  Remove rust spots with non-abrasive cleaners or mild acidic solutions such as oxalic acid or citric acid-based products.

Passivation and Maintenance

• انفعال:
  Passivation treatments enhance the natural formation of the chromium oxide layer, بهبود مقاومت در برابر خوردگی.
  This process involves immersing stainless steel parts in nitric or citric acid solutions, which remove free iron and contaminants from the surface.
• Periodic Maintenance:
  Regular cleaning combined with periodic passivation helps maintain the integrity and longevity of stainless steel equipment.
  Inspections for scratches or surface damage are recommended to prevent localized corrosion.

Cleaning in Industrial Food Processing Environments

• در محل تمیز کردن (سیپ) Systems:
  Many food processing lines employ automated CIP systems that circulate cleaning and sanitizing agents through equipment without disassembly.
  Stainless steel’s corrosion resistance allows it to withstand frequent exposure to caustic soda, اسید نیتریک, and steam at elevated temperatures.
• Steam-In-Place (چیدن):
  Steam sterilization complements CIP by providing high-temperature microbial control.
  Food-grade stainless steel can tolerate the thermal stresses of SIP while maintaining surface integrity.

Tips for Maintaining Stainless Steel Appearance

• Wipe in the Direction of the Grain:
  Stainless steel often has a brushed or directional finish. Cleaning along the grain helps maintain the surface appearance.
• Avoid Mixing Metals:
  Contact with dissimilar metals like carbon steel can cause galvanic corrosion and rust stains. Use dedicated cleaning tools and avoid cross-contamination.
• Use Stainless Steel Polishing Products:
  Specialized polishes and cleaners restore shine and provide a protective layer, reducing fingerprints and smudges.

12. پایان

Food-grade stainless steel, primarily grades 304 وت 316, serves as the backbone of modern food safety and processing.

آنها دوام, بهداشت, and regulatory compliance make them ideal for everything from kitchens and breweries to pharmaceuticals.

هر چند 316 carries a higher price, آن را مقاومت در برابر خوردگی برتر in acidic and saline conditions makes it the material of choice where long-term performance and safety are non-negotiable.

In an era of increasing food safety standards and environmental awareness, food-grade stainless steel remains essential for ensuring کیفیت, رعایت, وت sustainable operation in food-related industries.

LangHe: ریخته گری فولاد ضد زنگ دقیق & خدمات ساختاری

LangHe یک ارائه دهنده قابل اعتماد از ریخته گری از جنس استیل ضد زنگ با کیفیت بالا و خدمات ساخت فلزی دقیق, خدمت به صنایع که در آن عملکرد, دوام, و مقاومت در برابر خوردگی بسیار مهم است.

با قابلیت های پیشرفته تولید و تعهد به تعالی مهندسی, LangHe قابل اعتماد را ارائه می دهد, راه حل های فولادی ضد زنگ سفارشی برای برآورده کردن نیازهای برنامه کاربردی.

قابلیت های فولاد ضد زنگ ما شامل می شود:

• ریخته گری سرمایه گذاری & ریخته گری موم گمشده
  ریخته گری با دقت بالا برای هندسه های پیچیده, اطمینان از تحمل محکم و پایان سطح برتر.
• ریخته گری & قالب گیری پوسته
  ایده آل برای اجزای بزرگتر و تولید مقرون به صرفه, مخصوصاً برای قطعات صنعتی و ساختاری.
• ماشینکاری CNC & پس از فرآیند
  خدمات کامل ماشینکاری از جمله چرخش, آسیاب کردن, حفاری, صیقل, و درمان های سطحی.

آیا شما به اجزای با دقت بالا احتیاج دارید, مجامع ضد زنگ پیچیده, یا قطعات مهندسی سفارشی, LangHe آیا شریک قابل اعتماد شما در ساخت فولاد ضد زنگ است.

با ما تماس بگیرید امروز برای یادگیری چگونگی LangHe می تواند راه حل های فولاد ضد زنگ را با عملکرد ارائه دهد, قابلیت اطمینان, و دقیق نیازهای صنعت شما.

 

متداول

است ، 304 یا 316 stainless steel food grade?

بله, هر دو 304 وت 316 فولاد ضد زنگ are considered food-grade.

• 304 is widely used in kitchenware and food processing equipment due to its excellent corrosion resistance and affordability.
• 316 حاوی مولیبدن, offering better resistance to chlorides and acids, آن را ایده آل برای more aggressive food environments (به عنوان مثال, salty or acidic foods).

که بهتر است, 304 یا 316 فولاد ضد زنگ?

316 فولاد ضد زنگ به طور کلی است بهتر in terms of:

• مقاومت در برابر خوردگی, مخصوصاً در marine or acidic environments.
• دوام and lifespan in harsh cleaning or sanitation processes.

هر چند:

• 304 is more مقرون به صرفه and performs well in most general food-contact applications.

پایان: انتخاب کردن 316 برای high-corrosion یا high-humidity تنظیمات; otherwise, 304 is sufficient.

که بهتر است, 430 یا 304 فولاد ضد زنگ?

304 است. است بهتر نسبت به 430 in most food applications:

• 304 است وابسته به اوستن stainless steel with higher محتوای نیکل, giving it superior مقاومت در برابر خوردگی وت دوام.
• 430 است. است وابسته به فری, contains no nickel, و هست مقاوم در برابر خوردگی کمتر, though it’s more affordable وت مغناطیسی.

استفاده کردن 430 only for محیط های خشک یا decorative kitchen components; استفاده کنید 304 کجا moisture or cleaning chemicals are present.

است ، 420 stainless steel food grade?

بله, 420 فولاد ضد زنگ can be considered food grade, اما با محدودیت ها:

• این است وابسته به مارتنز, meaning it can be hardened by heat treatment and used in cutlery and blades.
• هر چند, آن را corrosion resistance is lower نسبت به 304 یا 316, ساخت آن less suitable for wet or acidic food environments.

Best use: چاقو, تیغ, and cutting tools—not for storage tanks or processing equipment.