It’s one of those pieces of information that we all seem to misplace…what really IS the difference between Aluminum Association, American Standard and Sharp Corner products?
First, let’s name that shape! The base, or depth, is often noted as the first dimension of the shape. The thickness, or web, is the thickness of the base/depth. Lastly, the legs or flanges are the uprights of the channel.
Each of the different types, Aluminum Association (AA), American Standard (AS) and Sharp Corner (often called Architectural) have a different combination of leg and interior corner types.
Aluminum Association (AA) has curved (radius) interior corners and straight legs with flat ends.
Need help remembering? We like to make a connection between letters AA in Aluminum Association, and the flat ends of the legs.
American Standard (AS), on the other hand does not have ANY flat or sharp corner in its interior or legs. The legs taper from thick to thin and have rounded ends. You can almost see the shape of an “S” between the rounded legs and the radius interior corner.
Everything about “Sharp Corner” is what it sounds like! 90 degree interior corners and straight legs with flat ends make everything angular. Sharp Corner, or Architectural also only comes in aluminum alloy 6063.
Aluminum, whether or not you know, is present in our daily lives in some fashion. But how did it get that way?
Let’s step back to look at how aluminum is made.
The first step in aluminum production is mining. Mining takes place in Bauxite-rich regions of the world such as the Caribbean, Australia and Africa. Bauxite is a naturally occurring ore that contains aluminum silicates that took millions of years to create from the natural chemical weathering of rocks.
After mining comes refining. Bauxite alone does not create aluminum, it’s the process of grinding the Bauxite and adding it to a mix of caustic soda and lime to which high heat is applied. After this intense process of heat and pressure occurs, aluminum oxide is created and precipitated out of the mix. It is washed and heated again. Now the mix looks like a white powder and is called ‘Alumina’. Alumina is also known as ‘aluminum oxide’.
Alumina is then smelted, which is an electrolytic reduction process. Electric current is passed through the bath of dissolved alumina and the aluminum metal is created and separates from the original chemical solution.
We aren’t done yet! After the aluminum is created it goes back into a furnace and is mixed with other metals or elements according to a precise scientific recipe in order to create a molten metal that is chemically suitable for certain applications. Purification then occurs and the molten metal is cast into ingots or molds and cools, awaiting its final processing.
Lastly, the ingot or cast material is either rolled, forged, drawn or extruded into its final form: sheet, plate, bar, tube or custom extrusion.
Bar stock can end up as the screws you buy from a hardware store and sheet products could be formed into a filing cabinet you use for important documents.
Next time you use or see something in your daily life that is aluminum- remember the long process it took to get that way and all the people and processing that happened along the way.
Given its assets of strength, corrosion resistance, and easy weldability, it’s no wonder stainless steel is so widely used across many industries. Each stainless steel family – austenitic, martensitic, ferritic, duplex, and precipitation hardening – is determined by the alloying elements in its chemical structure and the crystal structure of the steel itself. While all stainless steels share the same basic characteristics, each family has an asset making it particularly good for certain uses. For example, the low carbon found in ferritic stainless steel makes it highly malleable and excellent for welding. On the other hand, stainless steels in the martensitic family contain a high percentage of carbon, greatly increasing its tensile strength and impact resistance. Duplex steel is unique because it combines two of those families, austenitic and ferritic, to create a stainless steel with the benefits of both. Austenitic stainless steel has good corrosion and impact resistance, but the nickel used in its alloy adds to the production cost. Ferritic stainless steel is known for its ability to resist stress cracking, but the alloys used in ferritic steel’s composition make it more susceptible to corrosion. By combining these to make duplex steel, you can reap the performance benefits of both types while keeping costs down.
How is Duplex Steel Made? Duplex steel production begins like all stainless steel: the iron ore is smelted and combined with alloying elements such as nickel, molybdenum, chromium, and others. However, duplex steel’s chemical composition has a higher level of chromium than most stainless steels (typically 25% or more) and a lower percentage of nickel (less than 9%). It also contains a small amount of nitrogen, which helps improve the weldability of the finished steel. Once combined, the molten steel alloy is forged and left to cool. As the steel solidifies, the grain structure of the steel is formed into ferritic crystals; at this point, the entire product is ferritic steel. However, as it continues to cool to room temperature, more and more grains will begin to convert to austenitic steel until it becomes roughly 50-50 of each type. The reason duplex steel is so strong is due to the intermixing of these grains, much like the fat marbling on a prime steak. If the austenitic and ferritic steel were in distinct layers, that would leave one type more prone to cracking or corrosion, which risks weakening the other. In duplex steel, the interspersing of the grains means they reinforce the steel’s strength while minimizing each other’s weaknesses.
Advantages of Duplex Stainless Steel While duplex steel makes up a fairly small part of the global stainless steel market, it has some clear advantages compared to other families of stainless steel:
• Strength: Stainless steel is already a strong material on its own, but duplex steel can be 2 to 3 times stronger than austenitic or ferritic steels.
• Corrosion resistance: Duplex stainless steel has comparable or even higher levels of corrosion resistance than austenitic steels. Additionally, its high level of chromium provides more protection against crevice corrosion and pitting.
• Cost: Perhaps the greatest appeal of duplex steel is that it offers so many benefits while requiring less molybdenum and nickel, which keeps costs low. The strength and durability of duplex steel can also contribute to a longer lifetime use with less required maintenance, which helps money.
Disadvantages of Duplex Stainless Steel You might wonder, with all the benefits of duplex steel, why is it not in greater demand? There are a few disadvantages which limit its use: • Production: Due to its unique chemical composition, advanced knowledge is needed to produce this steel.
• Performance at low temperatures: Duplex steel has excellent impact resistance, except at very low temperatures. The ferrite in the duplex steel becomes brittle and prone to cracking.
• Performance at high temperatures: The structure of duplex steel can be negatively altered by very high temperatures, even with brief exposure. This includes the heat produced during welding, although the addition of nitrogen and a skilled welder can help prevent damaging the steel.
One of the best ways to ensure worker safety in industrial environments is by preventing falls. Proper footwear with non-skid soles is a must, but there will still be a risk of slipping on stairs and walkways. A textured surface in these areas will produce more friction while walking, providing better traction to prevent worker falls. One of the most common methods to improve slip resistance is the use of diamond plate in these high-traffic areas.
What is Diamond Plate? Diamond plate goes by many names, including tread plate, checker plate, and deck plate. Whatever the name, it all refers to the same thing: metal flooring with a raised diamond pattern on one side. It can be made of various types of materials from metals to plastic, but is most often produced from aluminum, hot rolled steel, and stainless steel. Because aluminum is naturally corrosion resistant, aluminum diamond plate is a favored choice for outdoor areas or other environments where the plate is in contact with water. Industrial kitchens, loading docks, and fire escapes often make use of aluminum diamond plate. The surface is able to withstand corrosion and abrasions, and can be easily cleaned. Steel has the strength advantage over aluminum, making steel diamond plate even more hard-wearing and strong. For this reason, diamond plate made from steel is often used in structural applications such as stairs and ramps. While it offers less corrosion resistance than aluminum, steel diamond plate’s sturdiness holds up well through regular use and cleaning chemicals. It is ideal for indoor location usage such as shop floors and walkways.
Production of Diamond Plate Although diamond plate may look intricate with its raised interlocking patterns, the process of making it is fairly straightforward. Using a combination of heat and pressure, metal can be made into diamond plate by stamping or hot rolling. With the stamping method, the metal (generally aluminum) can be used at room temperature. The aluminum is run through a series of large rollers, with each pair of rollers having one raised side and one smooth. As the metal passes through each roller, the massive pressure of the patterned roller embosses those shapes onto the aluminum’s surface. Once finished, the diamond pattern will be firmly stamped into the raised side while leaving the other side smooth. For steel diamond plate, hot rolling is the usual method of production. A steel slab is flash heated to just above its recrystallization point, and quickly passed through the rollers to produce the diamond pattern and desired thickness. Afterwards the steel is allowed to cool slowly, which helps prevent any major alternations to its mechanical properties. Once cooled to room temperature, the steel plate will have the raised diamond pattern on its surface.
Why Use Diamond Plate? Diamond plate is most often found in any area where extra traction is needed to help reduce slips and falls. This safety practice applies most importantly to workers, but benefits their usage of industrial vehicles as well. A warehouse loading dock surface made of diamond plate keeps workers steady on their feet, but also provides better traction for forklifts. Finally, the extra strength and durability of the metal plate allows the dock to withstand the heavy weight of forklifts without damage.
The forging of metal sheet and plate is often just the first step in its overall processing. Sawing will give you the desired size, but depending on the intended purpose of the metal, further operations will need to be done. Material removal services enable metal producers to create the exact customer specifications for components, using hole punching, drilling, and notching. Each process results in material removal, but the choice of method can depend on the metal’s thickness, the location of where the removal will take place, and other factors.
The Material Removal Process Hole Punching This shearing process involves a tool with sharp edges capable of punching through a piece of metal. Think of a cookie cutter: no matter what the shape, if the cutter is pressed quickly and firmly into the dough, you’re left with precise edges once the piece is removed. Hole punching works the same way on metal sheet and plate. Whether done using electrical, hydraulic, or pneumatic power, if sufficient force is applied, any shaped hole can be made in the metal.
Notching Much like hole punching, notching is a shearing operation using a sharp-edged tool. The difference lies in the removal’s location. While hole punching can take place anywhere on the metal, notching occurs only on its edges. Once those notching cuts are performed on the metal’s perimeter, additional bending or forming can be done.
Drilling This type of material removal uses a drill bit rather than a shearing tool. As the drill is applied to the metal, it continually removes the material until the bit pierces through. While a hand drill can be used, more often this process involves a machine known as a drill press. The operator uses the machine handles to lower the bit onto the metal, which helps enable more precise drilling.
Advantages and Disadvantages Hole Punching Hole punching is an appealing option for several reasons, but especially because of its speed. The presses used for hole punching can be incredibly quick, allowing multiple metal pieces to be processed within a short period of time.
Quick processing means a higher production volume, making this highly cost-effective. The other advantage is flexibility, since hole punching easily creates shapes other than round. Whatever the shape needed – round, square, triangular – the hole punching press can cut that into the metal. However, successful hole punching is limited to metal pieces with a thinner diameter. It is also dependent on the sharpness of the press, and punching through metal wears on the tool. If not kept sharp, a worn tool leads to punches that are incomplete or have sloppy, rough edges.
Notching Since notching is a shearing process like hole punching, they share similar pros and cons. The notching tool is fast, and while the process often involves creating vertical cuts, it can be modified to create different shapes. And like hole punching, this type of material removal is best done on thinner pieces of metal. Greater ease of cutting helps ensure the notches will be clean-edged and precise. Thicker metal can be processed, but requires greater force which is tough on the notching tool. The tool wear requires more supervision and maintenance to best help keep it sharp for notching.
Drilling Unlike hole punching and notching, which cut through the metal, drilling gradually pierces through it to remove material. While slower than a shearing method, drilling helps to prevent distortion of the metal part. The force needed for punching or notching tools can sometimes leave the metal bent around the location of the cut. Drilling is much better at keeping the surrounding area unaffected, and can be done successfully even on very thick pieces of metal. In addition, drilling is much more affordable since the necessary equipment is less expensive than the tools needed for other material removal options. However, the use of a drill bit does have its issues. This process can only create a round hole, unlike notching and punching. There is more friction involved due to drilling being a longer process, and friction produces heat which can negatively affect the metal. The friction also wears away at the drill bit, which may need replacement or sharpening to keep the hole precise.
The word “metallic”: a term synonymous with adjectives such as bright, gleaming, and reflective. However, newly-produced metal straight from the mill isn’t very shiny; in fact, it looks and feels rather rugged. Its appearance is referred to as “mill finish”, and it has a rough and irregular surface texture. The finish is dull, and its color often patchy due to metal oxidation or contamination from mill oil. While it looks unrefined, depending on its use mill finish can be acceptable. Why spend extra time and money to make unfinished metal look better when appearance is unimportant? However, the majority of consumers prefer their metal products to be smooth and shiny. Beyond the look of mill finish, other processes such as shearing can leave metal with rough or sharp edges. To improve the overall quality of the metal, polishing is often done to create a smooth and shiny surface. But when a finer degree of finishing is needed for certain applications, additional processing such as superfinishing is done.
Superfinishing Simply put, superfinishing is a level beyond the typical processing done to metal products. The metal has already gone through some type of finishing such as polishing or another surface modification process. To the naked eye, polishing leaves a gleaming surface and metallic shine, but the process can actually result in microscopic structural irregularities on its surface. These irregularities are referred to as the residual amorphous layer. Unlike the rest of the metal which retains its crystalline structure, the amorphous layer has scattered atoms creating a disordered surface. Superfinishing is necessary for situations where removal of that amorphous layer is critical to the metal component’s use.
The Superfinishing Process During a primary finishing process like polishing, a great deal of friction is needed to smooth away any pits or bumps marring the metal’s surface. On the other hand, the secondary process of superfinishing is a much more precise operation using lower friction. The best way to create lower friction is by the use of a very fine abrasive agent. The height of a superfinishing abrasive agent may only measure from 5 to 8 micrometers: too small for successful polishing, but effective in wearing away the amorphous layer. After the selection of stone or sandpaper with an extremely fine grit, the abrasive is applied on the metal’s surface while the item rotates in the opposite direction. This is done one small section at a time, both for precision and to keep friction to a minimum. Additional thermal protection is provided by using a lubricant, which helps reduce any heat produced from friction.
Advantages of Superfinishing Superfinishing is useful for both functional and aesthetic purposes: • Appearance: the metal is left with tiny crosshatch marks, creating an attractive brushed-metal finish.
• Low Tolerances: the amorphous layer removal performed during superfinishing means the metal’s measurements are much more precise. Polishing may leave metal looking shiny, but on a microscopic level, the surface is still uneven. Superfinishing ensures that the metal’s surface is uniform, because the crosshatching is the same height on every part of the component. The metal’s dimensional accuracy is improved, creating better seals and more precise assembly when the part is used in applications.
• Prolonged Use: precise assembly allows for less friction created during use, because pieces are less likely to press and slide against each other. This reduces wear on the metal, which then requires less maintenance and enables a longer period of use. Automotive parts like rods and shafts are typically superfinished to help extend the lifetime of the part.
Disadvantages of Superfinishing • Finish: depending on the consumer’s taste, a polished finish may be considered more appealing than a superfinished one.
• Cost: additional equipment is needed to perform superfinishing, adding to the metal’s overall cost.
• Time: while superfinishing is not a particularly lengthy process, the operation does add to the overall processing period for that part. This prolongs the time before a finished product can be shipped or sold.
Carbon steel is a widely used material, found in items from structural steel to kitchen knives. However, these industries do not necessarily use the same grade of steel. At its most basic, this metal group is made up of any steel alloy with added carbon. The carbon percentage will usually be somewhere between 0.05% to 2.0% of the metal’s overall weight. In any chemical composition, a range of 0.05 to 2.0 is a significant margin. Steel is no different: when it comes to formulating steel alloys, the variance in carbon percentage has a transformational effect on the produced metal. Carbon strengthens and hardens the steel, but decreases its ductility. That means the higher the carbon percentage, the less flexible the steel becomes. A high-carbon steel grade put under high or repeated stress would be more brittle and liable to crack. A grade of steel with lower carbon content will be more ductile, but not nearly as strong. So before starting a project with carbon steel, you should carefully consider the grade you select. It can make a big difference in the end result’s success. Reviewing these six questions beforehand can help in making your choice:
1. Will the carbon steel be machined? Machining is a process where the parts and shapes are cut from the metal. Because lower carbon grades are relatively softer steel, they are more easily and efficiently machined. A high carbon grade can be used, provided the alloy’s chemical composition includes sulfur which improves the steel’s machinability. Without sulfur, the hardness of high carbon steel will result in major wear of the cutting tools.
2. Will the carbon steel be welded? In general, the same grades of lower carbon steel more suited for machining can be more easily welded as well. High carbon steels can be used, but often require additional treatments before and after welding. And in contrast to machining, the steels grades containing sulfur are not recommended for use in welding. The sulfur in these alloys will have a higher risk of developing cracks at the weld join.
3. Does the carbon steel need to be heat-treatable? When it comes to heat, a good rule of thumb is 0.3. Steels with a carbon content of 0.3% or higher can be heat treated easily. This is due to the carbon itself, which helps the formation of martensite crystallization within the steel, reinforcing its hardness and strength. Grades of lower carbon steels lack the carbon necessary for martensite formation, making heat treatments unsuccessful.
4. Does the carbon steel need good formability? Due to the wide margin of carbon percentages across grades, it can be difficult to say which grades might be more formable than others. The selected grade is often dependent on the shape: rolled sheet requires a much more ductile type of steel, but forming pieces such as angle and beam can involve a wider grade range. Overall, the more ductile carbon steels – meaning, lower carbon grades – are much easier to form.
5. Does the carbon steel need high corrosion resistance? Because steel’s main element is iron, it is vulnerable to oxidation leading to corrosion. This is an accepted fact that when using any grade of carbon steel, it will develop a certain amount of rust. In applications where corrosion resistance is a high priority, it may be better to consider using another material such as stainless steel instead. To minimize corrosion of carbon steels, they can be coated to create a barrier between the metal and its environment. This can go from involved processes such as galvanization or plating the metal to simply applying a coat of paint.
6. How strong a carbon steel is needed? The steel’s application is crucial to deciding the strength needed for your metal. High carbon steel is incredibly strong, but if intended to be used for making small parts such as nuts and bolts, your needs would be better served by low carbon steel’s machinability. But while low carbon steel is more formable, it would be worth the greater effort when making tools to use high carbon steel for its hardness and durability. While it may be tempting to select the hardest and strongest material available, its actual use should be an important factor in selecting the right carbon steel.
Since the early 1900s, stainless steel has been a fixture in our everyday lives. This alloy can be found everywhere, from watches to skyscrapers and aircraft. Its strength, corrosion resistance, and affordability make it an appealing choice for many projects. Even better, stainless steel is fully recyclable! The alloying elements used in its chemical composition can be extracted from melted stainless steel, and then reused with no degradation in their performance. Having learned of its valuable properties, it is little wonder that so many different industries rely upon using stainless steel. With a wide range of grades and alloys available on the market, a manufacturer can be sure to find a type of stainless steel to suit their needs. Here are five of the most common uses of this metal alloy:
Construction Modern construction is largely dependent on stainless steel due to its strength, flexibility, and resistance to corrosion. Its durability makes it a good choice for both interior and exterior use. Skyscrapers and commercial buildings often have frames and exterior cladding made of stainless steel. Its durability means less time and expense can be spent on maintenance, since the metal remains rust-free.
Energy and Heavy Industry The oil, gas, and chemical industries present a great challenge to construction. These industries typically operate in environments which involve high temperatures and corrosive, toxic substances. Specialized grades of stainless steel have been developed for these industries, designed for enhanced corrosion resistance and able to handle extreme ranges of temperature. These “super-steel” grades are used for storage tanks, pipework, and valves. Crude oil is an extremely corrosive substance, so stainless steel is invaluable in the construction of offshore rigs and drilling components. Stainless steel can also be found making up the equipment for renewable energy sources such as wind or hydro power. Its resistance to developing rust allows it to withstand the corrosive effects of seawater and varying temperatures.
Automotive and Transportation Stainless steel has long been an integral part of automotive manufacturing, although mainly used in the past for exhaust systems and trim. With the rise of environmental concerns, more auto makers are expanding their use of stainless steel in structural components due to its recyclability. The transportation and shipping industries are highly reliant on stainless steel, from shipping containers to tanker trucks. Transporting chemicals and other substances requires strong, non-reactive metals like stainless steel. Its strength also allows for thinner containers, which saves on fuel costs. Its corrosion resistance then requires less maintenance and easier cleaning of those containers and other transport equipment.
Medical Instruments The production of medical instruments has involved stainless steel for well over a century. While bacteria can form on its surface, its natural corrosion resistance means a stainless steel tool is unlikely to have cracks or grooves where the bacteria can harbor itself. This makes for easy and thorough sterilization of stainless steel medical tools. The stainless steel instruments can be sterilized and reused for many cycles before they will show enough wear to be discarded.
Food Production and Catering When it comes to cooking, once again stainless steel’s durability and corrosion resistance play key roles. Many foods such as tomatoes are highly acidic, leading to corrosion and discoloration of aluminum or copper cookware. The more reactive a metal, the more it can potentially affect a food’s flavor, often for the worse. Stainless steel is an ideal material for food production and storage because it has strong corrosion resistance, which means the metal does not react to its environment or the substances stored inside it. This durability means less waste; knives, cutlery, and cookware can be used for many years before showing excessive wear. Stainless steel is an even more important material in commercial food production. As in the medical industry, equipment sterilization is the utmost priority, and stainless steel can hold up to cleaning cycles involving high temperatures and strong anti-bacterial products. Its non-porous surface means bacteria are unable to hide away during cleaning, and lowers the chances of carrying over any germs between food production batches.
Newly forged metals are extremely hard – hard to a fault, because such a degree of inflexibility makes the metal very brittle. This applies even to alloys made of naturally ductile metals such as aluminum. However, after some type of tempering treatment is done to ease the tension within the metal’s structure, the aluminum will be left stronger and more resilient than before.
Before beginning, it’s important to determine whether the aluminum being tempered is heat-treatable or not. If the aluminum alloy belongs to one of the following series, it should not be heat treated: Series 1xxx: pure aluminum Series 3xxx: alloyed with manganese Series 4xxx: alloyed with silicon Series 5xxx: alloyed with magnesium Pure aluminum and aluminum alloyed primarily with one of the elements in the list above do not respond to heat treatment. In these cases, the material can be toughened through other means such as cold working or work hardening.
For the other aluminum series, their tempering can be done through annealing, homogenizing, solution heat treatment, and aging. Aging can then be further split into two groups: natural aging, and artificial aging (also known as precipitation hardening). Whatever the method chosen, the purpose of tempering is to alter the aluminum’s physical and mechanical properties without changing its shape.
Annealing For aluminum series not considered heat-treatable, annealing is the method used to temper the metal. Work hardening means the metal is placed under repeated strain during use, which causes the grain structures within it to slide against each other. These stretched areas are called slip planes, and as the aluminum continues to be used, there will be fewer and fewer areas left that are not already slip planes. If the aluminum continues to be used without tempering, eventually the metal will be overworked and break. The annealing process essentially performs a reset on the aluminum. By exposing it to a relatively low heat of 570 to 770 degrees F, the strain within the metal lessens as the crystalline grain structure returns to its original form. Once cooled, the aluminum can again handle the creation of more slip planes.
Homogenizing When casting aluminum parts using molds, the edges of the part will cool faster than the interior. This uneven cooling affects the structure of the part since some areas, particularly around the edges, will have grains of pure aluminum. The interior may be more combined with its alloying elements, but have remaining pockets of pure aluminum. Because pure aluminum is quite soft, this means those grainy areas will be weaker. Homogenizing reduces this issue by heating the aluminum to just shy of its melting point, around 900 to 1000 degrees F, and allowing a gradual cooling. Unlike the heat of the mold, the uniform heat during homogenizing allows the internal structure to develop more uniformly. Once this is done, the cast aluminum part will be much sturdier.
Solution Heat Treatment Solution heat treating is similar to annealing, but the metal is quenched rather than being allowed to cool on its own. When aluminum cools naturally, a greater degree of precipitation occurs. This means the alloying elements within the metal may drop out of place within the metal’s internal structure, rather than being as fully integrated as when newly forged. The sudden cooling from a quench means the alloying structure will be locked into place. Depending on the type of alloy, the aluminum is heated to 825 to 980 degrees F, almost near melting point. This heat prompts the aluminum and alloying elements to better combine into solid solution. It is then immediately immersed in water to bring a sudden drop in its temperature. After tempering, the part will be stronger due to its improved homogenization.
Aging After quenching, there is some precipitation which happens naturally in aluminum alloy. However, this is not a drawback – the alloying precipitation helps to reinforce and lock in place the aluminum’s microstructure. If left at room temperature, natural aging will continue to develop for up to 5 days, with most of the hardening taking place within the first 24 hours. This aging window means aluminum can be shaped after solution heat treating, leaving a much stronger piece after both processes are complete. With artificial aging, the process of precipitation in some alloys may require a second round of tempering to reach its maximum strength. The metal is exposed to a fairly low temperature of 240 to 460 degrees F, just enough to encourage the alloying elements to begin to precipitate within the metal’s interior. It is then quenched again and allowed to finish cooling at room temperature. While more labor intensive, artificial aging will result in a significantly stronger metal in a shorter time period.
In all likelihood, if someone were asked the difference between carbon and stainless steel, the answer would involve appearance: one is dull and one is shiny. That might sound simple, but it’s also true! While the finish of each steel is the most obvious difference, there are other, more significant ways they differ. Learning more about the characteristics of each steel type will help determine which steel is most appropriate for a project.
Corrosion Resistance The most significant difference between the two is the high degree of corrosion resistance found in stainless steel. Both types of steel are vulnerable to corrosion due to their iron content, which reacts with oxygen to form rust. However, the addition of chromium in stainless steel alloy provides much more protection against corrosion. The chromium in stainless steel reacts more quickly with oxygen than iron, and the resulting chromium oxide forms a protective layer on the surface of the metal. The chromium oxide prevents further oxygen interaction with the metal, effectively stopping any continued corrosion. Carbon steel alloys may also contain chromium, but not in the amounts found in stainless steel. This means carbon steel is vulnerable to the corrosive effects of rust, which leads to damaged metal unless regularly maintained. So in situations where corrosion resistance is a big concern, stainless steel will be the best choice.
Appearance Adding chromium as an alloying element in stainless steel not only boosts corrosion resistance, it is also the source of the metal’s distinctive shine. Carbon steel naturally has a flatter finish, and its vulnerability to corrosion leads to tarnishing and other discoloration. It can be sanded to smooth the metal and produce more shine, but unless some type of coating is applied to the polished carbon steel, the same rust and discoloration will develop. Stainless steel, on the other hand, has a natural luster which polishing can increase to a mirror shine. Polishing also provides even more corrosion resistance to the metal, without the need for an additional protective coat. This is because any existing irregularities are sanded down during polishing, so corrosive particles are less likely to cling to the metal’s surface. For projects where aesthetics is an important factor, stainless steel may be preferable over polished or painted carbon steel.
Mechanical Properties Both carbon and stainless steels are produced in multiple types and grades, so it can be difficult to make a clear distinction between the two kinds of steel. In general, stainless steels tend to be more ductile, while carbon steels have greater tensile strength. This is due to the carbon alloying percentage found in carbon steels. Carbon makes steel harder, to the point of becoming very strong and brittle with high-carbon steels. However due to the variety of available carbon and stainless steels, these properties may not apply across the board. A low-carbon steel can be more ductile than certain types of martensitic stainless steel. Some stainless steel grades will be harder and with greater tensile strength than a low-carbon steel. Ultimately, the mechanical properties of any kind of steel should be considered for its specific use in a project.
Cost As a general rule, stainless steel will be more expensive than carbon steel due to its alloying elements. Carbon steel may contain other elements, but is mainly made up of iron and carbon which are fairly affordable. Stainless steel is created with the addition of chromium, and also has higher amounts of alloying elements such as nickel and manganese. Each additional element to the stainless steel’s chemical composition increases the cost. For a lower budget project where aesthetics is a lesser priority, carbon steel will be the best way to go.