304 vs. 316 Stainless Steel

304 vs. 316 Stainless Steel

Stainless steel is one of the most popular and well recognized metals, known for its attractive appearance, low maintenance requirements, and resistance to corrosion and staining. Unlike regular carbon steel, stainless steel does not readily corrode in the presence of water. When the strength and toughness of steel are required, along with the need for corrosion resistance, stainless is often the answer.

Steel is an alloy, a combination of several metals. Steel always contains iron and carbon, along with small percentages of other elements. The amount and type of elements that are added during fabrication result in many different classes and grades of steel. So, for example, all types of stainless steel contain at least 10% chromium by weight.

When exposed to air and moisture, the iron in most steels will rust, creating an active iron oxide film that accelerates corrosion by continuously forming more iron oxide. The large amount of chromium present in stainless reacts to form a film of chromium oxide on the surface. This passive film prevents further corrosion on the surface, while also blocking its spread into the metal’s internal structure.

Different grades and surface finishes of stainless steel are made to suit different applications and environments. The most common types of stainless steel are alloys 304 and 316. Both are austenitic stainless steels, which means they are non-magnetic and easily worked.

304 Stainless Steel

The most versatile and widely used of all stainless is grade 304 stainless steel, also known as A2 or “18/8” stainless because it contains 18% chromium and 8% nickel. This stainless grade provides the best all-around performance due to its chemical composition, mechanical properties, weldability and oxidation resistance. As a result, 304 stainless is available in a wider range of products, forms and finishes than any other stainless steel.

Stainless steel 304 can be easily brake- or roll-formed into a variety of components for applications in industry, architecture, and transportation. The balanced austenitic structure of grade 304 stainless enables it to be severely deep drawn without intermediate annealing. As a result, 304 is dominant in the manufacture of drawn stainless parts such as sinks, hollow-ware and saucepans.

Other well-known uses of 304 stainless include kitchen appliances, cutlery, surgical instruments, and industrial equipment. It is also commonly used in commercial kitchens and food processing plants because it can be steam-cleaned and sterilized and does not require paint or other finishes.

304 Pros: Strong, low-cost, easily formed and welded, readily available in many forms, resists stains and corrosion.

304 Cons: Not fully resistant to corrosion & pitting in acidic chemical or marine environments.

316 Stainless Steel

Grade 316 stainless steel is the standard molybdenum-bearing grade, second in importance to 304 amongst the austenitic stainless steels. The significant percentage of molybdenum (2-3%) gives 316 better overall corrosion resistant properties than grade 304, particularly higher resistance to pitting and crevice corrosion in acidic and salt-water environments, giving it the name “marine grade” stainless.

Grade 316 also contains a higher percentage of nickel than 304 stainless steel (10% vs. only 8%) which results in much improved corrosion resistance. This makes 316 stainless a better choice for use in chemical processing plants, oil refineries, and medical devices, as well as saltwater & marine applications, such as docks, catwalks, railings, and roofs.

316 Pros: Stronger than 304 stainless, more resistant to corrosion & pitting from saltwater and chemicals, good forming and welding characteristics.

316 Cons: More expensive and somewhat more difficult to weld and form than 304.

Industrial Metal Supply stocks a wide range of stainless steel forms, including bar, sheet & plate, tubing, pipe, angle, and perforated sheet. Drop by one of our six locations in Southern California and Arizona, or visit us online today!

heat conducting metal

Best Metals for Conducting Heat

Thermal conductivity is the term that describes how quickly a material absorbs heat from areas of high temperature and moves it toward areas of lower temperature. The best heat-conducting metals have high thermal conductivity and are useful for many applications, such as cookware, heat exchangers, and heat sinks. On the other hand, metals with a lower rate of heat transfer are also useful where they can act as a heat shield in applications that generate large amounts of heat, such as airplane engines.

Here’s a ranking of heat conducting metals and metal alloys from lowest to highest average thermal conductivity, in Watts/meter-K at room temperature:

  1. Stainless Steel (16)
  2. Lead (35)
  3. Carbon steel (51)
  4. Wrought iron (59)
  5. Iron (73)
  6. Aluminum Bronze (76)
  7. Copper brass (111)
  8. Aluminum (237)
  9. Copper (401)
  10. Silver (429)

Stainless Steel

With one of the lowest thermal conductivities for a metal alloy, stainless takes much longer to conduct heat away from a source than, say, copper. This means that a pot made of stainless would take much longer to heat up food than a copper-bottom pot (though stainless has other benefits). Steam and gas turbines in power plants use stainless steel because of its heat resistance, among other properties. In architecture, stainless steel cladding can resist high temperatures longer, keeping buildings cooler in sunlight.


While aluminum has a slightly lower thermal conductivity than copper, it is lighter in weight, cheaper, and easier to work with, making it a better choice for many applications. For example, microelectronics such as LEDs and laser diodes use tiny heat sinks with aluminum fins that project into the air. Heat generated by the electronics transfers from the chip to the aluminum and then to the air, either passively or with the help of forced airflow convection or a thermoelectric cooler.


Copper has a very high thermal conductivity and is much cheaper and more available than silver, which is the best metal of all for conducting heat. Copper is corrosion resistant and resists biofouling, which makes it a good material for solar water heaters, gas water heaters, and industrial heat exchangers, refrigerators, air conditioners, and heat pumps.

Other factors affecting heat conduction

When considering the best metals for heat conduction, you must also take into account other factors in addition to thermal conductivity, which affect the rate of heat flow. For example, the initial temperature of the metal can make a huge difference to its heat transfer rate. At room temperature, iron has a thermal conductivity of 73, but at 1832°F, its conductivity drops to 35. Other influences include the temperature difference across the metal, the thickness of the metal, and the surface area of the metal.

For the largest selection of metals in the Southwest, contact Industrial Metal Supply.

Data taken from Engineering Toolbox.

best metals for welding

Best Metals for Welding

The best metals for welding depend on the project design and budget, the skill and experience of the welder, and the welding process to be used. Almost any metal can be welded, but some are easier than others for creating a high-quality, defect-free weld.

Some types of metal require special equipment, such as a vacuum or gas chamber, limits on heat exposure, or pre- and post-welding heat treatment. Some perform better with different types of welding, whether stick, TIG, or MIG. Choosing the right electrode and filler material for the base metal and following prescribed welding procedures is essential. Each specific situation depends on the base metal’s chemical makeup.

Low Carbon Steel

Also known as mild steel, low carbon steel contains a very small percentage of carbon (less than 0.3%) and up to about 0.4% manganese (AISI 1018 steel). This commonly used steel is very ductile, due to its low carbon content. High ductility means high weldability because it reduces the chance of brittleness in the heat affected zone (HAZ), which can lead to hydrogen cracking. Low carbon steel can be welded using almost any type of equipment and is one of the best metals for welding.

Stainless Steel

Stainless steel can be quite weldable, depending on the grade. Ferritic and austenitic stainless steels can be welded fairly easily, but not martensitic stainless types, which tend to crack. Stainless steel tends to warp under high heat, which can affect the shape and strength of the final workpiece. Another issue is that the chromium in stainless will combine with carbon during the welding process, leaving the piece more susceptible to rust without its chromium oxide protective layer. To prevent this problem, don’t heat the workpiece above the recommended temperature, or choose a low-carbon stainless grade.


Creating a defect-free weld in aluminum is different than welding steel, but can be done by following the prescribed guidelines. Choosing the proper grade is important, as some types are much easier than others to weld. Because of aluminum’s high thermal conductivity, heat is transferred away from the weld very quickly. Equipment with a higher welding current may be required to supply the necessary heat. As it cools, aluminum shrinks significantly more than steel, so special care must be taken to prevent craters and cracking. Finally, the natural aluminum oxide coating on the base metal can add contaminants, and should be removed prior to welding to avoid porosity in the weld.

Other Metal Types

Other metals, including magnesium, copper, cast iron, titanium and superalloys such as Inconel, can be welded. These will typically require special equipment and expert skill, making them less weldable for traditional job shops and hobbyists.

Industrial Metal Supply is your one-stop shop in the Southwest for all things metal. Visit our catalog for a wide selection of metal products, including steel, stainless steel, and aluminum, as well as all the machines, supplies, and accessories you need for welding.

cleaning stainless steel

Ways to Clean Stainless Steel

Stainless steel is a wonderful material, providing a strong, attractive, waterproof and “stainless” finish to many different types of products, such as appliances, hand-rails, tanks, etc. But stainless does not always remain rust-free, and it often needs cleaning, especially outdoors or in environments around food, pharmaceuticals or other chemicals. At the same time, when preparing stainless steel for fabrication or finishing, it’s essential to ensure the surface is clean. There are fundamental differences in these two ways of cleaning stainless steel.

Cleaning Stainless Appliances

When cleaning the surface of stainless steel appliances, vent hoods or tanks, start with the simplest solutions first. Water, a drop of dish soap, and a microfiber cloth applied with elbow grease can accomplish a lot. Be sure to dry off any leftover water to prevent streaking. To shine the finish, rub a cloth containing a couple drops of mineral oil in line with the metal grain. If the surface shows cloudy oxidation or rust, use a non-toxic, non-acidic product such as Flitz Polish to remove the oxidation. For heavier stains, grease, mold or rust, use a commercial stainless steel cleaner that contains a degreaser.

Metal Surface Preparation

In the process of making a stainless steel product, oxide scale can form on the steel as a result of hot rolling, thermal treatments, welding, and brazing. Lubricants and coolants may be applied to the stainless during cutting and forming operations and bits of metal from cutting tools may become embedded in the surface. Shop dirt, fingerprints, and grime may accumulate on the stainless during handling and storage, and even protective paper or plastic sheets may permanently adhere to the surface over time. All these contaminants must be removed in the surface preparation process before welding, priming, painting, electro-static painting, and powder coating stainless steel.

Is Stainless Steel Really Stainless?

Stainless steel contains at least 10 percent chromium, which is a highly reactive metal. The chromium on the surface of a piece of stainless oxidizes (rusts) quickly in the presence of oxygen or water molecules in the atmosphere. These oxidized chromium molecules form a very thin, tight film, called a passivation layer that acts as a barrier against the surrounding air, preventing any further oxidation of the steel.

But when this protective film is broken up in the process of manufacturing, a heavy scale can form on the surface. This scale could cause a welding or adhesion failure, and it is removed by “pickling,” or applying a combination of acids to the surface. Typically nitric acid is part of the solution, because it encourages the passivation layer to form. Another method for removing scale from stainless steel is sandblasting.

Certain types of welding can create a light scale or a heat tint discoloration on the surface. Any type of screw holes or other attachment points that create a break in the passivation film leave the stainless susceptible to rust.

Applying a pickling solution or metal degreaser to remove oil, grease, scale and rust should be followed by a protective coating to prevent further rust and leave a brighter surface finish.

Industrial Metal Supply carries cleaners, polishers, and degreasers for stainless steel and a range of ferrous and non-ferrous metals.

corrosion resistant metals

4 Types of Metal That Are Corrosion Resistant or Don’t Rust

We usually think of rust as the orange-brown flakes that form on an exposed steel surface when iron molecules in the metal react with oxygen in the presence of water to produce iron oxides. Metals may also react in the presence of acids or harsh industrial chemicals. If nothing stops the corrosion, flakes of rust will continue to break off, exposing the metal to further corrosion until it disintegrates.

Not all metals contain iron, but they can corrode or tarnish in other oxidizing reactions. To prevent oxidation and breakdown of metal products, such as handrails, tanks, appliances, roofing or siding, you can choose metals that are “rust-proof” or more accurately, “corrosion-proof.” Four basic types of metals fall into this category:

  • Stainless steel
  • Aluminum metal
  • Copper, bronze or brass
  • Galvanized steel

Stainless Steel

Stainless steel types, such as 304 or 316, are a mix of elements, and most contain some amount of iron, which easily oxidizes to form rust. But many stainless steel alloys also contain a high percentage of chromium – at least 18 percent – which is even more reactive than iron. The chromium oxidizes quickly to form a protective layer of chromium oxide on the metal surface. This oxide layer resists corrosion, while at the same time prevents oxygen from reaching the underlying steel. Other elements in the alloy, such as nickel and molybdenum, add to its rust-resistance.

Aluminum metal

Many aircraft are made from aluminum, as are car and bike parts. This is due to its light weight, but also to its resistance to corrosion. Aluminum alloys contain almost no iron and without iron, the metal can’t actually rust, but it does oxidize. When the alloy is exposed to water, a film of aluminum oxide forms quickly on the surface. The hard oxide layer is quite resistant to further corrosion and protects the underlying metal.

Copper, Bronze and Brass

These three metals contain little or no iron, and so do not rust, but they can react with oxygen. Copper oxidizes over time to form a green patina, which actually protects the metal from further corrosion. Bronze is a mixture of copper and tin, along with small amounts of other elements, and is naturally much more resistant to corrosion than copper. Brass is an alloy of copper, zinc, and other elements, which also resists corrosion.

Galvanized Steel

Galvanized steel takes a long time to rust, but it will eventually rust. This type is carbon steel that has been galvanized, or coated, with a thin layer of zinc. The zinc acts as a barrier preventing oxygen and water from reaching the steel, so that it is corrosion protected. Even if the zinc coating is scratched off, it continues to protect nearby areas of the underlying steel through cathodic protection, as well as by forming a protective coating of zinc oxide. Like aluminum, zinc is highly reactive to oxygen in the presence of moisture, and the coating prevents the iron in the steel from further oxidation.

Industrial Metal Supply carries a wide range of rust-resistant metals for a variety of applications.

The Industrial Metal Supply Stainless Steel Guide

Stainless Steel is considered as one of the best metals, and provides various benefits including its ease of fabrication, strength, and anti-bacterial properties. We encounter different types of stainless steel in multiple places in our everyday lives whether we realize it or not. From its discovery in 1913, stainless steel has been a popular and preferred metal by many partly due to its lustrous appearance, as well as its durability and versatility.

In our guide, you’ll discover some more benefits and interesting facts about Stainless Steel.

Industrial Metal Supply Co. Stainless Steel Guide

Types of Stainless Steel

To distinguish different types of stainless steel, we measure the metal’s microstructure at room temperature to learn more about the overall composition. In total, there are five primary types of stainless steel:


With a similar structure to low alloy steels, ferritic stainless steel boasts strong resistance to corrosion cracking. Using little to no nickel — one of the priciest alloying elements — it’s less expensive than austenitic steel, and typically has a significant percentage of chromium (11.2% – 19%). However, it is also less formable than austenitic steel. Finally, ferritic steel is magnetic.


This is the most common variety of stainless steel, making up more than 70% of overall production. It’s a well-rounded structure, with adequate weldability, formability, and creep resistance. Unlike ferritic steel, austenitic varieties are for all intents and purposes non-magnetic. Austenitic steel gets its name from the crystalline microstructure, which is made of isometric crystals. When you add a large proportion of molybdenum (over 6%), the steel becomes superaustenitic, which gives it better protection against crevice corrosion and cracking.


This stainless steel type contains chromium, nickel, molybdenum, and carbon, which makes for a more brittle microstructure. However, it is generally tougher than the austenitic and ferritic varieties. Though they have relatively low formability, these alloys can be tempered as you would with carbon steels. Adding a small amount of nickel improves the martensitic steel’s lack of weldability.


These hybrid alloys are called duplex because the composition is about 50% austenitic and 50% ferritic. By combining the two microstructures, you end up with a new form that has more strength than both. The strong composition also leads to improved corrosion resistance and stress cracking resistance. Since duplex steel has such a large proportion of ferritic alloy, this type is also magnetic.

Precipitation Hardening

Finally, this martensitic type has been made even stronger by adding aluminum, copper, and niobium, in conjunction with a precipitation hardening process. It involves heat-treating the metal to create particles in the crystal lattice, which help to stop irregularities in the microstructure and boost the alloy’s overall strength.

Carbon Steel vs Stainless Steel

Carbon and stainless steel are both created with percentages of carbon and iron, but their characteristics are fairly distinct. Below, we’ve outlined the benefits and drawbacks of each alloy.

Carbon Steel Characteristics and Uses

This is the most basic form of steel available. A tiny proportion of carbon is added to drastically improve the metal’s hardness, but it also makes the carbon steel less ductile. Typically, the percentage of carbon in this steel is much higher than in stainless steel, and it largely defines how the metal behaves. Any other alloying elements — such as manganese, tungsten, or chromium — have a smaller effect on the carbon steel’s overall properties.

That being said, carbon steel still makes up around 90% of today’s steel production. The construction industry uses about a quarter of the world’s steel, which can be found in almost every building made by humans, as well as in the construction of roads, railways, other infrastructure, appliances, and buildings. It can be used to make a wide range of products, such as playground equipment, automobile parts, structural beams, knives, steel wires, and refrigerator parts. The alloy is susceptible to corrosion, so it needs to be galvanized for outdoor use. It’s also not nearly as attractive as stainless steel, with a dull, uninspiring finish. Overall, the higher carbon content increases the metal’s durability, heat distribution, and malleability, but it also lowers its melting point.

Stainless Steel Characteristics and Uses

On a superficial level, stainless steel is an attractive metal, with a lustrous and reflective finish that is easy on the eyes. This is due to the high percentage of chromium (over 10.5%) in the alloy, which changes its appearance and also helps to prevent corrosion. Unlike carbon steel, stainless steel has a chromium oxide coating that protects against rust and stains. Some stainless steel alloys are even resistant to sulfuric or phosphoric acid.

You’ll find stainless steel in countless applications, including handrails, cutlery, razor blades, hot water tanks, and medical instruments such as surgical tools, medical equipment, and surgical implants. Its architectural uses include bridges, monuments, and sculptures. It is also used in automotive and aerospace applications, jewelry, and many others. It is used as a finish for refrigerators, freezers, countertops, and dishwashers. It is ideal for food production and storage, as it does not affect the flavor of the food. During the Art Deco period, stainless steel was hugely influential in creating decorative and structural elements that we revere today. However, stainless steel is heavier than carbon steel and aluminum, with the lowest strength-to-weight ratio. That makes it unsuitable for aviation and other industries where weight is a critical factor.

Overall, stainless steel’s decorative and rust-resistant properties make it the clear winner for many people, but carbon steel is still the preferred metal for manufacturing and construction purposes.