Stainless steel is widely used in a range of industries, including aerospace, manufacturing, food processing, and marine applications. Steel materials like 304 stainless steel are popular in a range of industries, thanks to their impressive corrosion resistance and durability. However, stainless steel can still become susceptible to the effects of harsh operating environments.
Various techniques can be used to reduce the risk of corrosion damage and achieve the desired surface finish in polished stainless steel. Below, we’ll discuss the critical role corrosion resistance plays in various stainless steel finishing techniques and how each works to protect steel parts.
Importance of Corrosion Resistance in Polished Stainless Steel
Corrosion resistance is critical for high-performing stainless steel components, particularly those that must perform in aggressive environments such as offshore or nuclear industries. Properly polished stainless steel surfaces are much less likely to experience localized corrosion or accumulate deposits than rough or badly polished surfaces, resulting in improved performance over the component’s service life. The right finish can also improve consistency and the overall look of stainless steel parts.
How to Improve Corrosion Resistance in Polished Stainless Steel
There are several major ways professionals can improve corrosion resistance in polished stainless steel. Consider the following options for protecting stainless steel components:
Passivation
Passivation is an essential chemical treatment for enhancing corrosion resistance in stainless steel components. Passivation uses an acidic or alkaline solution to form a thin layer of chromium oxide (Cr203) on metal surfaces. This passive film prevents rust from forming in harsh operating environments.
Electropolishing
Electropolishing is widely used to deliver a corrosion-resistant surface in stainless steel and other metal alloy forms. This electrochemical process involves placing metal goods in an electrolytic bath and applying a current to remove extraneous surface material, including iron residue. This prevents chemical reactions that can lead to corrosion while creating a smooth, even finish.
Mechanical Polishing
This traditional finishing method works mechanically instead of chemically to make surfaces visibly smoother. Mechanical polishing uses abrasives to remove scratches, stains, and other irregularities from stainless steel surfaces. Manufacturers can also use sandpaper to polish surfaces. Mechanical polishing is useful for focusing on specific areas. However, it can be time-consuming and requires skill to effectively implement.
Regular Cleaning and Maintenance
Ongoing maintenance can help keep polished stainless steel goods in top condition. Regular cleaning can remove dirt and chemicals that build up over time. Additionally, inspecting surfaces during cleaning can reveal early signs of corrosion.
Coating Protection
Applying special coatings onto stainless steel surfaces can offer added protection in highly corrosive environments. Common coating options include:
Powder coating
Metal plating
Painting
Each one offers unique advantages in terms of durability, cost-effectiveness, and overall protection.
Protect Your Stainless Steel Parts With Services Built to Block Corrosion
While finishing processes can vary by application, stainless steel components consistently benefit from improved corrosion resistance. At AAA Metals, we provide in-depth stainless steel polishing services for long-lasting protection. Depending on your needs, we can provide a more comprehensive solution, including converting materials, finishing manufactured pieces, and delivering completed orders to your distribution center or warehouse.
Handrails provide safety, structure, and aesthetic elements for walkways, stairways, platforms, and passageways. They are used in recreational, commercial, industrial, and residential settings. Flat metal bar stock is a popular choice for handrails, and it is available in many materials, widths, thicknesses, and lengths.
AAA Metals supplies a range of bar stock materials for flat bar handrail applications, along with grinding, polishing, and finishing capabilities to meet your requirements.
Bollards are solid vertical posts in front of buildings or structures that protect against vehicle collisions and other forces that can cause damage. They are installed on storefronts, sidewalks, trailheads, parking lots, and more. In addition to protecting buildings, occupants, and passersby against collisions, bollards are also used to control traffic and guide pedestrians.
Types of Bollards
Bollard posts can be categorized based on their intended application. Depending on how they are installed and if they can be removed, bollards can be permanent or temporary. Here are the most common types of bollards, each one designed for specific purposes:
Street or Traffic Line Bollards: These bollards are usually installed on streets, public squares, or sidewalks to demarcate vehicle, bike, and foot traffic. They can also prevent access to restricted areas in these public spaces.
Pedestrian Bollards: These are used specifically to guide pedestrian traffic and separate them from vehicles. They’re also used in visually defining property perimeters while adding aesthetic flair. Pedestrian bollards can be lighted to illuminate a walkway at night.
Construction Bollards: You’ll find these bollards in construction zones, where they limit or guide vehicle traffic to protect workers, pedestrians, and drivers from construction hazards.
Ram-Raid Bollards: These are installed around shops and other commercial buildings to prevent ram raids, a type of “smash and grab” burglary where a vehicle crashes through the doors or windows of a store while thieves loot products. Ram-raid bollards can withstand vehicle collisions and help deter ram-raiding.
How Metal Bollards Are Made
A metal bollard is made by rolling sheet metal into a pole-like shape and fitting or welding the top, which can be domed, flush, or open. Then the bollard is polished or powder-coated for the desired finish. Below are some of the common metal materials, finishes, and sizes used in making bollard poles.
Common Bollard Materials
The specific metal used in making a bollard depends on its need or functionality—where and how it’s going to be used. Our most common materials for bollards include:
Stainless steel
Grade 304
Grade 316
Bollard Finishes
Bollard posts are finished in a variety of ways, such as:
Stainless Steel Polishing: Polished stainless steel bollards offer a clean, modern look that also provides more hardness and corrosion resistance than mild steel.
At AAA Metals, we usually polish bollards to a #4 or Scotch Brite finish, but we can customize this based on our customers’ desired finish.
Common Sizes
Bollard poles come in various sizes, but the most common outer diameter sizes include:
4.5 inches
6.625 inches
8.625 inches
AAA Metals can also produce custom bollard diameters and heights based on our customers’ unique specifications.
Bollards come in different types and materials for different needs, so you can customize them based on your unique specifications. For high-quality metal bollards, turn to the experts at AAA Metals. Our bollards meet all applicable industry standards and can provide robust, long-lasting protection for your building or other structure. We specialize in fabricating high-quality tubes and pipes, meeting ASTM, AMS, ASME, Mil-Spec, and QQS standards as needed.
Stainless steel components for the food processing industry must be strong, durable, non-reactive, and smooth. These qualities enable the material to stand up to the rigors of food handling, processing, and preparation. In particular, smooth finishes on stainless steel are vital to maintaining safe and sanitary conditions by preventing the buildup of debris and bacteria on the surface. Experienced suppliers with specialized knowledge are best equipped to polish stainless steel to meet these critical hygiene and performance requirements.
Learn more about the stainless steel polishing process, types of finishes, types of polishing, and more.
Stainless Steel Polishing
Polishing stainless steel is an important finishing step that can improve both aesthetic and functional qualities of many products and components. Benefits include:
Achieving a desired aesthetic, from rough and dull to mirror-like shiny finishes
Minimizing irregular surfaces that can harbor dirt, debris, bacteria, and other contaminants
Reducing the likelihood of damage from oxidation and corrosion
Improving the performance and service life of polished parts
The Stainless Steel Polishing Process
The traditional process of polishing stainless steel involves treating the material with increasingly finer abrasive materials, which include ceramics, zirconia, and alumina. Over the course of three to seven steps, stainless steel surfaces are scoured with these grinding materials until the desired surface finish is achieved. Using grit strengths ranging from 50 to 3,000, operators can create standard finishes ranging on a scale of 0-10.
Finishes with the lowest numbers (#0-2) are considered “mill finishes,” indicating their minimal treatment after production. These mill finishes use treatments such as annealing (slow cooling), pickling, and passivation (acid baths) for protection and mildly increased smoothness. A #3 finish provides a slightly smoother finish, but it features rough, uniform parallel lines.
Finishes #4 and higher represent surfaces that are more satiny or shiny. Finishes higher than #6 offer varying degrees of sheen, from the reflective #7 to the glassy, mirror shine of #9 and #10.
Types of Finishes for Food-Grade Stainless Steel
Finishes #4 to #6 are the most commonly used finishes for applications requiring food-grade materials. #4 is often called “dairy finish” for its common use in dairy and other commercial processing equipment. #5 satin and #6 satin Scotch-Brite™ finishes have a higher reflectivity and polish and are used for such products as appliances, countertops, food-processing equipment, cabinets, cases, protective panels, and other food-grade environments. These applications benefit from the smooth, clean look of these finishes that minimizes the appearance of fingerprints and oils while also minimizing the risk of cross-contamination.
AAA Metals specializes in creating #4, #5, and #6 finishes for our customers’ food-grade stainless steel needs.
Abrasive Polishing for Food-Grade Stainless Steel
Hygiene standards require that food-grade stainless steel features a degree of smoothness (typically finishes #4-#6) that prevents dirt, debris, bacteria, and other microorganisms from lurking in grooves, pits, scratches, and other recessed areas. Stainless steel can meet these standards when buffed or rubbed with these abrasive polishing materials:
Sandpaper
Polishing compounds
Grinding wheels
Common abrasives include alumina, zirconia, and ceramic materials, applied in progressively finer granularity. Proper polishing of food-grade stainless steel makes the surfaces easy to clean while ensuring no contaminants are introduced during polishing.
Electropolishing for Food Grade Stainless Steel
Electropolishing is another way to polish stainless steel for use in food-grade applications. The process involves immersion in an electrolyte bath charged with DC power, which improves the cleanliness, corrosion resistance, and surface finish of the stainless steel component. These smooth surfaces are highly resistant to accumulating debris and bacteria, and they are easily cleaned and sterilized to meet any food-grade application.
Benefits & Applications
Busy food handling and processing environments require equipment and utensils that meet stringent food industry requirements for performance and cleanliness. Food-grade stainless steel can be used in products as diverse as food processing equipment, knife blades, worktops, cookware, appliances, spatulas, and more. With easy maintenance and cleaning requirements, stainless steel is an ideal material for long-lasting performance and hygienic conditions.
Polishing for Food-Grade Stainless Steel Services From AAA Metals
At AAA Metals, our decades of experience with specialized metal supply and distribution include extensive knowledge and equipment for polishing stainless steel to meet diverse industry needs, including food-grade polishes on stainless steel. Request a quote to get started on your next stainless steel polishing project.
A weld test coupon is a small piece of metal used to test a welder’s proficiency in various welding procedures. Weld coupons are commonly utilized for applications such as welder qualifications, training, practicing difficult joints, and more. Here, we will dive into the specifics of weld coupons and their different applications, as well as the purpose of welder qualification tests.
What Is a Weld Coupon?
Welding is critical to various industrial tasks; therefore, it’s important for welders to demonstrate their proficiency to ensure they can deliver quality results. Many welding certifications require welders to showcase their skill level by passing a welding coupon test according to the required standards and codes.
Welding coupons are small pieces of metal, typically in plate or pipe form, used to evaluate a welder’s skill through destructive testing, visual inspection, and other methods. This allows welding professionals to demonstrate and determine another welder’s ability to deposit a high-quality weld joint.
Other Applications of Weld Coupons
Weld coupon testing is ideal for various applications, including:
Welder Qualification/Certification. Weld coupons can be used for welding qualification tests, which determine whether a person or machine can produce a quality weld that is up to code.
Welder Training. Weld coupons can be used to demonstrate proper welding techniques and assess a trainee’s skills.
Welding Procedure Qualification. Welders must be able to meet specific inspection criteria to become qualified for certain welding procedures. Weld test coupons can be used for this qualification process.
Mock Fit-up/Practice Joints. Professional welders and trainees can use weld coupons to develop mock-ups and practice complex joints.
Procedure Qualification Record (PQR) Materials. A PQR documents what happened during weld coupon testing as well as the result of the test.
Electron Beam Welding. Electron-beam welding is a fusion welding process in which a beam of high-velocity electrons is applied to two materials to be joined.
Laser Beam Welding. Laser beam welding (LBW) is a welding technique used to join pieces of metal or thermoplastics through the use of a laser.
What Is the Welder Qualification Test?
A welding qualification test is a hands-on skills test conducted by a certified welding inspector to determine the quality of a welder or machine’s welds based on the code or procedure required by the industry standard, job site, or company. Specifically, a welding qualification test demonstrates a welder’s ability to deposit a quality weld when following a qualified welding procedure. As such, welders are typically provided with a Welding Procedure Specification (WPS) to follow while performing the test.
If a welder can demonstrate their ability to perform a weld that requires a high skill level, they will be deemed competent to perform welding procedures that are easier than what was demonstrated during the qualification test.
Welder qualification tests can take various forms. The reasons for this include:
Each welding process requires different skill sets to perform.
Different materials present their own difficulties or issues when welding and therefore require different skills.
Different-sized workpieces require specific skills to account for varying diameters and thicknesses.
Welding different-shaped materials, like plates and pipes, require different skills.
Each welding code has its own unique requirements.
Weld Coupons From AAA Metals
Welding coupons play a critical role in evaluating a person or machine’s ability to accurately carry out certain welding procedures and create high-quality joints. At AAA Metals, we can manufacture weld test coupons in high quantities for use in various applications, including qualification tests, recalibrating robotic welders, training/practice, and more. Using grinders, we can create weld coupons with specific angles that can be used to practice and perform welding tests at difficult angles.
Stainless steel is one of the most preferred manufacturing materials due to its great durability. It is also easy to work with, as it can be cut, welded, and bent while maintaining strength. Moreover, stainless steel lasts considerably longer than other substances and does not easily rust or corrode.
For steel construction and other industrial applications, stainless steel is available in various forms and shapes. Particularly, it is utilized in applications where a corrosion-resistant and hard material is required.
Here are some of the most common stainless steel shapes used for a variety of purposes:
Angles
Also known as L-shaped, stainless steel angles have two straight legs (angled at 90°) that may be of equal or varied length and are tapered. They are extensively used for construction purposes, such as edge trims, frames, and brackets. They also have exceptional corrosion resistance and are advantageous in applications where hygiene is essential, including commercial kitchens, medical facilities, and laboratories.
Channels
Stainless steel channels, called C-shaped, have top and bottom flanges with a connecting web. Depending on the particular grade, the applications for stainless steel channels can vary. For instance, Type 304 channel beams are suitable for medical equipment and the transport of chemicals, pigments, crude oils, and refined oils. Meanwhile, Type 316 channels are often used for building and architectural purposes. They are also more expensive than 304 due to their greater corrosion resistance.
Hexagonal Bars
Stainless steel hexagonal bars provide good machining qualities. Thus, they are excellent for repeatedly turned components, such as bolts and nuts. Additionally, hexagonal bars are common in the medical sector, food processing industry, tooling, and mechanical engineering.
Hollow Bars
Stainless steel hollow bars offer great corrosion resistance and are normally available in various grades and sizes to meet different technical and manufacturing needs. These bars are commonly used in the construction, medical, food production, and pharmaceutical industries.
Round Bars
Round bars have smooth surfaces used for construction applications that do not require high-strength reinforced concrete. They are widely used on beams, column stirrups, pipelines, roads, and other similar industrial purposes.
Flat Bars
Flat bars are durable materials commonly used in applications requiring narrower widths and diameters. They are often available in straight lengths or custom sizes. Furthermore, stainless steel flat bars are appropriate for use in the building, petrochemical, beverage production, and architectural industries.
Tee Sections
Stainless steel tee sections — also known as T-profiles, T-bars, or T-beams — have T-shaped cross sections created by longitudinally cutting the webs. They are resistant to corrosion and have simple surfaces to clean and sterilize. Furthermore, they are frequently used in various structural and architectural applications, including trims, edgings, frames, and facades.
Sheets
Stainless steel sheets are made from an alloy of steel and chromium. Although the thickness of stainless steel sheets can differ, they are typically thicker than metal foils or leaves but thinner than metal plates. Their common uses are in the construction, food processing, automotive, chemical, and marine industries.
Plates
Stainless steel plates do not stain, corrode, or rust as easily as normal carbon steel since their chromium content prevents surface corrosion when exposed to air and atmospheric moisture. As a result, they are the most preferred stainless steel shape in applications that require little maintenance but high corrosion resistance.
Choose AAA Metals for High-Quality Metals and Metal Processing Services!
AAA Metals is a global stainless steel shapes supplier with polishing and finishing services. We also offer premium metal processing services for round bars, square bars, plates, pipes, tubes, sheets, and more. Browse our extensive metal stock to see if we offer the specific material you require!
Contact us for more information on our stainless steel shapes and processing services. You can also request a quote, and we will be happy to assist you with your needs!
The appearance of stainless steel comes down to how it was finished. Some stainless steels look smooth and consistent, while others look grainy and rough — all of which are outcomes of the finishing processes. Whether you are looking for durability, corrosion resistance, or low cost, there is a distinct finish for your requirements.
This article will define a surface finish, describe the finishing process, and discuss the different types of stainless steel finishes.
What Is a Surface Finish?
Surface finishing alters the outermost layer of a metal by adding, removing, or reshaping. This essential technique aims to protect the metal while improving its appearance.
The surface finish chosen is critical where fabrication processes will be used. For example, rough surface finishes are appropriate when the steel is ground before painting and gluing, whereas smooth surface finishes are preferred when the steel is blended. On the other hand, a visually appealing surface finish is necessary for projects where design is a priority.
How Does the Stainless Steel Finishing Process Work?
The primary finishing method is to “cold roll” the stainless steel through special rolls or dies. Cold rolling usually results in smoother, less pitted surfaces. It is then softened and de-scaled in an acid solution before the steel is given a final pass on polished rolls to improve its smoothness.
Different finishes suit various requirements. Here is a closer look at the commonly used finishes for most stainless steels and their applications.
What Are the Different Finish Types?
The various types of finishes are graded on a scale of 0 to 10.
No. 0
This finish is also known as Hot Rolled Annealed (HRA) steel. The plate is hot rolled to the required thickness before annealing, which results in a rough, scaled-black finish. This process does not produce a completely corrosion-resistant film on the stainless steel, and it is not suitable for general use except in specific high-temperature heat-resistant applications.
No. 1
The plate is hot rolled, annealed, pickled, and coated in this finish type. The process produces a dull, slightly rough surface ideal for industrial applications involving various plate thicknesses. Several applications of the No. 1 finish include the following:
Air heaters
Annealing boxes
Carburizing boxes
Firebox sheets
Furnace conveyors and linings
No. 2
The No. 2 finish can be classified into multiple subcategories:
– No. 2D
This finish type is the No. 1 finish after being cold rolled, annealed, pickled, and coated. It produces a more uniform matte finish than No. 1. It is also used in the following applications:
Chemical equipment
Electric range parts
Furnace parts
Railcar parts
Roofing
– No. 2B
This second subcategory is a No. 2D finish with a light skin pass cold rolling operation between the rolls. However, the No. 2B finish has higher reflectivity and brightness. It is also the most commonly produced and requested finish on sheet materials. It is typically used in applications such as the following:
Bakeware
Dyehouse equipment
Flatware
Pharmaceutical equipment
Plumbing fixtures
– No. 2BA
This type is referred to as a Bright Annealed (BA) finish. It is created by cold rolling a No. 1 finish on the steel surface with highly polished rolls. This aids in smoothing and brightening the surface, and its applications include the following:
Architectural components
Commercial refrigerators
Cookware
Fishing equipment
Surgical instruments
No. 3
This finish type is produced with an abrasive of 80-100 grit. It is also an excellent intermediate or starting surface finish for use when the steel will require additional polishing processes to a more refined finish after succeeding fabrication. Among its applications are the following:
Brewery equipment
Kitchen equipment
Food processing equipment
Scientific apparatus
The remaining finishes are defined by the eventual outcome of the finish rather than by a structured methodology:
4: Similar to No. 3 but with slightly higher polish and reflectivity; used in applications such as appliances, beverage equipment, elevator doors and interiors, and water fountains.
5: Satin; most widely used in coastal architectural elements where a reflective or bright finish is not suitable
6: Satin (Scotch-BriteTM)
7: Reflective but not clear; used in architectural and decorative applications
8: Mirrored; used in column covers, mirrors, ornamental trim, press plates, wall panels, and signage
9: Ultra-mirrored with a bead-blasted surface
10: Electropolished and heat-colored
High-Quality Finishing Services at AAA Metals
Finishes should always be specified and defined using industry-standard designations. At AAA Metals, we can make your project a reality!
We specialize in stainless steel polishing for consumables, discs, forgings, pipes and tubing, rings, and pumps in all industries. We have been a frontrunner in stainless steel polishing for over three decades, with complete in-house capabilities for belt sanding, grinding, face, edge, and OD polishing. Moreover, our advanced tools include multi-head machines and belt sanders with ceramic, zirconia, and nylon-impregnated polishing belts.
Contact us directly for more information on our high-quality stainless steel finishing services or other capabilities, or you can request a quote today!
Unlike standard machinery, marine equipment must endure sea air and salt spray for long periods, rusting at a faster rate for reduced operational efficiency. Stainless steel, while naturally resistant to corrosion, may still underperform in harsh marine conditions.
Marine-grade stainless steel, then, is the answer for coastal and other related applications. This variety of stainless steel boasts a particular strength, ruggedness, and high corrosion resistance compared to other metals. Read on to learn more about corrosion and the types of marine-grade stainless steel that best resist it in marine projects.
Avoiding Corrosion With Stainless Steel
In marine environments, salt is among the biggest threats to metal. It’s a highly corrosive substance, and salt spray from the sea can be a real problem for equipment in coastal operations. Through the chemical process of oxidation, iron molecules in steel produce flaky oxides on the metal’s surface when oxygen and iron molecules come into contact with water, causing deterioration. Corrosive elements like salt degrade steel components, most often in the form of rust.
One of the most common ways to avoid metal degradation is to use stainless steel, which is renowned for its anti-corrosive qualities. This alloy is mainly made up of iron, along with a combination of the following:
Aluminum
Chromium
Copper
Nickel
Nitrogen
Phosphorus
Selenium
Titanium
It’s the chromium that is primarily responsible for corrosion resistance at 10.5% or more of stainless steel’s material composition. A protective skin of chromium oxide forms on the material’s surface to safeguard the base metal against moisture exposure, preventing iron oxide and rust from forming.
Understanding the Different Grades of Stainless Steel for Marine Applications
Although all stainless steel grades are resistant to corrosion to some degree, marine-grade stainless steel is ideal for marine applications. Marine-grade steel boasts a level of corrosion and rust resistance that is superior to other metals, with various grades offering unique advantages in the marine industry.
Grade 316 Stainless Steel
Potentially the most common type of marine-grade stainless steel, Grade 316 stainless steel contains 16% chromium and up to 3% molybdenum, which is a higher percentage of this hard and tough metallic element than in other steel varieties. It also contains 8% nickel, which enhances resistance to caustic materials. This composition increases the metal’s resistance to the degradation and pitting that salt water can cause and increases marine components’ life span.
In addition to brine, Grade 316 is also highly resistant to iodides, bromides, chlorides, and sulfuric and fatty acids. It’s this durability that allows it to withstand harsh marine environments. Regarding fabrication, marine-grade stainless steel is quite compatible with welding and finishing services, making it simple to use as well as clean. Given its abilities, Grade 316 does tend to be more expensive than some other varieties, such as Grade 304.
Grade 304 Stainless Steel
Grade 304 stainless steel is another popular material that’s effective in marine environments. It’s composed of 18% chromium and 8% nickel, which give the metal good resistance qualities to caustic substances and moderate acids. It’s easy to work with, being a stainless steel grade that is simple to fabricate and clean.
This versatile metal is ideal for outdoor applications such as storage tanks, exhaust manifolds, electrical enclosures, piping, and wheel covers, and it’s available in varying aesthetics and finishes. Unfortunately, as it lacks molybdenum, Grade 304 is still prone to pitting, or localized corrosion, from chloride solutions typical in saltwater environments.
Contact AAA Metals for Marine-Grade Stainless Steel Solutions
The experts at AAA Metals Company Inc. are ready to help you choose the most suitable type of stainless steel for your marine application. Since 1978, we have built a reputation as a trusted partner for quality materials, proudly distributing numerous grades of stainless steel, titanium, nickel alloy, and hard-to-find metals. Our raw metal bars, rings, plates, forgings, discs, pipes, and tubing are available from stock, in mill form, precision cut, or polished.
We utilize our water jet and laser cutting, precision sawing, multi-shearing, and polishing capabilities to serve as your full-service supplier. Also, our global distribution network allows us to fulfill orders of virtually any size with competitive pricing to diverse businesses worldwide. To learn more about the AAA Metals difference and our material offerings for marine-grade stainless steel, contact us or request a quote today.
The food processing industry must meet strict standards and regulations for health and safety. As more and more facilities are implementing automated machinery and components for faster production, this equipment must be constructed from food-safe materials and finishes.
Food-grade stainless steel offers an optimal material choice for the food industry. Available in various grades, the many beneficial properties and features of stainless steel ensure that all food safety and hygiene standards are met, making it ideal for a wide range of food applications.
Stainless Steel Features & Benefits for the Food Industry
Stainless steel is a popular material choice for food handling applications for a multitude of reasons. Not only can the material withstand harsh temperatures, but its protective oxide layer protects against the formation of rust that could lead to food contamination. One of the most important attributes of food-grade stainless steel is that it contains no dangerous chemicals that could transfer into foods.
Other features and benefits that make stainless steel a good choice for the food industry include:
Great corrosion resistance
Extreme strength
Ease of cleaning
Non-reactive surface
Low maintenance costs
Impermeable surface to prevent contamination
Available in various finishes
Chemical and bacterial neutrality
Made to handle frequent cleanings with harsh detergents
Does not retain or transfer food smells
Choosing the Best Stainless Steel Food Grade for Your Application
While there are several types of stainless steel available, only a few are considered food-grade. Nearly all food-grade stainless steels come from the 300 and 400 series, including:
304 Grade Stainless Steel. 304 stainless steel offers an affordable option for nearly any food processing environment. It can withstand corrosion from several oxidizing acids, meaning it is easy to sanitize. It also boasts great weldability and formability, allowing it to be manufactured into various types of food processing equipment. Common applications for 304 stainless steel include storage tanks, fermentation vats, dishwashers, and more.
316 Grade Stainless Steel. 316 stainless steel is an austenitic alloy with high nickel and chromium content. Similar to other steel alloys, it can be continuously used at temperatures significantly higher than most food handling processes require. This grade is also resistant to chlorides (such as salt), alkalis, and acids, making it great for nearly any food application.
430 Grade Stainless Steel. This material has equal chromium content to grade 316 but only a fraction of the nickel content, making it a more cost-effective alternative for food processors. 430 grade stainless steel is highly resistant to organic and nitric acids, meaning it is often found in applications involving extended contact with mildly acidic compounds. This material is also resistant to oxidation, sulfur, and corrosion cracking.
Common Applications
Various applications within the food and beverage industry depend on food-grade stainless steel. Stainless steel is preferred over other materials in the following applications:
Beer kegs
Confectionary equipment
Conveyor systems
Double-wall transport containers
Evaporator tubes
Flour silos
Food mixers
Food pulverizers
Ice cream molds
Industrial ovens
Peeling machines
Syrup tanks
Tanks holding dairy
Contact AAA Metals for Premium Stainless Steel Metal Solutions
Food-grade stainless steel is ideal for various food processing applications, offering corrosion and heat resistance, durability, neutrality, and ease of sanitization. AAA Metals has been supplying and processing stainless steel and other metals since 1978. We offer various stainless steel materials for the food industry, including food-grade stainless steel sheets, pipes, and precision-cut pieces for your desired application. In addition, we offer in-house capabilities such as finishing, polishing, shearing, precision sawing, and waterjet cutting.
For more information about stainless steel for the food industry, or to learn more about our offerings, contact us or request a quote today.
If an application requires durable steel that’s designed to last, they’re likely to use stainless steel. Stainless steels are iron-based alloys that include a chromium content of at least 10.5% or higher. This level of chromium content facilitates the development of a passive chromium oxide layer on the steel’s surface, which allows for optimal corrosion resistance for every grade of stainless steel.
Stainless steel also tends to include other alloy content, including carbon, nickel, manganese, silicon, and molybdenum, each of which enhances certain stainless steel properties. Manufacturers often alloy stainless steel with these elements to increase stainless steel’s heat resistance, formability, and durability based on the needs of a particular application.
Depending on what you require, multiple grades exist to help you complete your next project. By understanding the differences between each grade, you’ll better be able to make the right selection.
300 Series Stainless Steel
The most popular stainless steel grade is the 300 series. 300 series stainless steels typically include nickel, chromium, and molybdenum content. They provide superior corrosion resistance, along with other benefits such as:
Excellent machinability
A non-magnetic austenitic crystalline structure
Resistance to high temperatures
Broad finishing options
Easy maintenance
Resistance to etching, scratching, and cracking
Thermal shock resistance
High creep strength
Nitriding and carburization resistance
Each of the 300 series stainless steel grades features different properties. These grades include:
303
303 stainless steel is extremely machinable because of its phosphorus and sulfur content. Applications for this steel include fittings, bolts, gears, and nuts in the aerospace industry.
304
The majority of applications that use 300 series stainless steel use grade 304. The automotive, nuclear, food and beverage, and shipping industries often use this grade. Additionally, welding applications often use a variation called 304L, which features a reduced amount of carbon content.
316
Some applications use 316 stainless steel due to its excellent corrosion resistance, particularly to chlorides like seawater and salt. The increased nickel and molybdenum content allows for this superior corrosion resistance. 316L is a low-carbon variation of this steel. 316 stainless steel often appears in marine and nuclear environments, while the pharmaceutical and chemical industries frequently rely on 316L.
Applications for 300 series stainless steels include a variety of materials in the automotive, construction, and aerospace industries, among many others.
400 Series Stainless Steel
For applications that require adequate corrosion resistance and a more cost-effective solution, 400 series stainless steel grades are available. This series normally contains a combination of manganese and chromium content. While these grades are resistant to corrosion, they aren’t as corrosion-resistant as the 300 series. Because of this, these grades tend to cost less.
Some of the key characteristics of 400 series stainless steel grades include:
Superior strength compared to carbon steel
A magnetic martensitic crystalline structure
Good surface finishing options
Non-hardenable via heat treating
Sufficient sustainability for applications requiring thinner materials and reduced weight
Resistance to scaling at high temperatures
Additional benefits include easy machinability, heat treatability to a wide range of strength and hardness levels, and good ductility.
The two main grades of 400 series stainless steel include:
416
This stainless steel grade contains sulfur for increased machinability. The quality of 416 stainless steel makes it compatible with many applications, including pumps, gears, valves, studs, and washing machine parts.
440C
If applications need stainless steel with high resistance to wear and increased durability, 440C stainless steel is a popular option. However, it’s not as corrosion-resistant as other grades. Nozzles, surgical instruments, and bearings use 440C stainless steel, along with other items that require material to retain its shape.
Applications for 400 series stainless steel include machine components, medical implements, and other parts that require added machinability and strength.
Stainless Steel from AAA Metals
For a selection of high-quality stainless steel products, turn to the experts at AAA Metals Company Inc. Since 1978, we’ve developed into a leading supplier of raw materials, including plates, discs, rings, bars, and much more using stainless steel and other alloys.
If you would like additional information about our metal stock and services, contact us today. To get started on a project using stainless steel or other alloys, request a quote.
