Steel vs. Aluminum
ALUMINUM VS STEEL COST
Cost and price are always an essential factor to consider when making any product. The price of steel and aluminum is continually fluctuating based on global supply and demand, fuel costs and the price and availability of iron and bauxite ore; however steel is generally cheaper (per pound) than aluminum (see galvanized vs stainless for more info on steel). The cost of raw materials has a direct impact on the price of the finished spinning. There are exceptions, but two identical spinnings (one in aluminum and one in steel) the aluminum part will almost always cost more because of the increase in the raw material price.
CORROSION RESISTANCE OF STEEL AND ALUMINUM
While malleability is very important for manufacturing, aluminum’s greatest attribute is that it is corrosion resistant without any further treatment after it is spun. Aluminum doesn’t rust. With aluminum, there is no paint or coating to wear or scratch off. Steel or “carbon steel” in the metals world (as opposed to stainless steel) usually need to be painted or treated after spinning to protect it from rust and corrosion, especially if the steel part will be at work in a moist, damp or abrasive environment.
STRENGTH & MALLEABILITY OF STAINLESS STEEL VS ALUMINUM
Aluminum is a very desirable metal because it is more malleable and elastic than steel. Aluminum can go places and create shapes that steel cannot, often forming deeper or more intricate spinnings. Especially for parts with deep and straight walls, aluminum is the material of choice. Steel is a very tough and resilient metal but cannot generally be pushed to the same extreme dimensional limits as aluminum without cracking or ripping during the spinning process.
WEIGHT DIFFERENCES IN STEEL AND ALUMINUM
Even with the possibility of corrosion, steel is harder than aluminum. Most spinnable tempers and alloys of an aluminum dent, ding or scratch more easily as compared to steel. Steel is strong and less likely to warp, deform or bend underweight, force or heat. Nevertheless, the strength of steel’s tradeoff is that steel is much heavier/much denser than aluminum. Steel is typically 2.5 times denser than aluminum.
The final application of the part will ultimately determine which material the part would be spun from, balancing all the limitations and advantages of each material. On some spinnings, it’s an easy call, while others are a tougher decision. If you or your engineering departments are on the fence with steel vs. aluminum dilemma, please contact the authority on metal spinnings at Wenzel Metal Spinning, Inc. and we will be happy to provide you with our expert opinion and supporting information. Additional information about steel and aluminum can be found on our materials page.
Cost and price are always an essential factor to consider when making any product. The price of steel and aluminum is continually fluctuating based on global supply and demand, fuel costs and the price and availability of iron and bauxite ore; however steel is generally cheaper (per pound) than aluminum (see galvanized vs stainless for more info on steel). The cost of raw materials has a direct impact on the price of the finished spinning. There are exceptions, but two identical spinnings (one in aluminum and one in steel) the aluminum part will almost always cost more because of the increase in the raw material price.
CORROSION RESISTANCE OF STEEL AND ALUMINUM
While malleability is very important for manufacturing, aluminum’s greatest attribute is that it is corrosion resistant without any further treatment after it is spun. Aluminum doesn’t rust. With aluminum, there is no paint or coating to wear or scratch off. Steel or “carbon steel” in the metals world (as opposed to stainless steel) usually need to be painted or treated after spinning to protect it from rust and corrosion, especially if the steel part will be at work in a moist, damp or abrasive environment.
STRENGTH & MALLEABILITY OF STAINLESS STEEL VS ALUMINUM
Aluminum is a very desirable metal because it is more malleable and elastic than steel. Aluminum can go places and create shapes that steel cannot, often forming deeper or more intricate spinnings. Especially for parts with deep and straight walls, aluminum is the material of choice. Steel is a very tough and resilient metal but cannot generally be pushed to the same extreme dimensional limits as aluminum without cracking or ripping during the spinning process.
WEIGHT DIFFERENCES IN STEEL AND ALUMINUM
Even with the possibility of corrosion, steel is harder than aluminum. Most spinnable tempers and alloys of an aluminum dent, ding or scratch more easily as compared to steel. Steel is strong and less likely to warp, deform or bend underweight, force or heat. Nevertheless, the strength of steel’s tradeoff is that steel is much heavier/much denser than aluminum. Steel is typically 2.5 times denser than aluminum.
The final application of the part will ultimately determine which material the part would be spun from, balancing all the limitations and advantages of each material. On some spinnings, it’s an easy call, while others are a tougher decision. If you or your engineering departments are on the fence with steel vs. aluminum dilemma, please contact the authority on metal spinnings at Wenzel Metal Spinning, Inc. and we will be happy to provide you with our expert opinion and supporting information. Additional information about steel and aluminum can be found on our materials page.
When designers require rugged, tough materials for their projects, steel and titanium are the first options that come to mind. These metals come in a wide assortment of alloys - base metals imbued with other metallic elements that produce a sum greater than its parts. There are dozens of titanium alloys and hundreds more steel alloys, so it can oftentimes be challenging to decide where to begin when considering these two metals. This article, through an examination of the physical, mechanical, and working properties of steel and titanium, can help designers choose which material is right for their job. Each metal will be briefly explored, and then a comparison of their differences will follow to show when to specify one over the other.
Steel
Perfected during the onset of the 20th century, steel has quickly become the most useful and varied metal on Earth. It is created by enriching elemental iron with carbon, which increases its hardness, strength, and resistance. Many so-called alloy steels also use elements such as zinc, chromium, manganese, molybdenum, silicon, and even titanium to improve its resistance to corrosion, deformation, high temperatures, and more. For example, steel with a high level of chromium belongs to the stainless steels, or those which are less prone to rusting than other alloys. Since there are many kinds of steel, it is hard to generalize its specific properties, but our article on the types of steel gives a good introduction to the various classes.
To speak generally, steel is a dense, hard, yet workable metal. It responds to the heat treatment strengthening process, which allows even the simplest of steels to have variable properties based on how it was heated/cooled. It is magnetic and can conduct both heat and electricity readily. Most steels are susceptible to corrosion due to its iron composition, though the stainless steels address this weakness to some degree of success. Steel has a high level of strength, but this strength is inversely proportional to its toughness, or a measure of resilience to deformation without fracture. While there are machining steels available, there are other steels that are difficult, if not impossible, to machine due to their working properties.
It should be clear that steel can fit a lot of different jobs: it can be hard, tough, strong, temperature or corrosive resistant; the trouble is that it cannot be all these things at once, without sacrificing one property over the other. This is not a huge problem though, as most steel grades are inexpensive and allow designers to combine different steels in their projects to gain compounding benefits. As a result, steel finds its way into nearly every industry, being used in automotive, aerospace, structural, architectural, manufacturing, electronics, infrastructural, and dozens more applications.
Titanium
Titanium was first purified into its metallic forms in the early 1900s and is not as rare as most people believe it to be. In fact, it is the fourth most abundant metal on Earth, but is difficult to find in high concentrations or in its elemental form. It is also difficult to purify, making it more expensive to produce than to source.
Elemental titanium is a silver-grey non-magnetic metal with a density of 4.51 g/cm3, making it almost half as dense as steel and landing it in the “light metal” category. Modern titanium comes either as elemental titanium or in various titanium alloys, all made to increase both the strength and corrosion resistance of the base titanium. These alloys have the necessary strength to work as aerospace, structural, biomedical, and high-temperature materials, while elemental titanium is usually reserved as an alloying agent for other metals.
Titanium is difficult to weld, machine, or form, but can be heat-treated to increase its strength. It has the unique advantage of being biocompatible, meaning titanium inside the body will remain inert, making it indispensable for medical implant technology. It has an excellent strength-to-weight ratio, providing the same amount of strength as steel at 40% its weight, and is resistant to corrosion thanks to a thin layer of oxide formed on its surface in the presence of air or water. It also resists cavitation and erosion, which predisposes it towards high-stress applications such as aircraft and military technologies. Titanium is vital for projects where weight is minimized but strength is maximized, and its great corrosion resistance and biocompatibility lend it to some unique industries not covered by more traditional metals.
Comparing Steel & Titanium
Choosing one of these metals over the other depends upon the application at hand. This section will compare some mechanical properties common to steel and titanium to show where each metal should be specified (represented in Table 1, below). Note that the values for both steel and titanium in Table 1 come from generalized tables, as each metal widely varies in characteristics based on alloy type, heat treatment process, and composition.
The first striking difference between titanium and steel is their densities; as previously discussed, titanium is about half as dense as steel, making it substantially lighter. This suits titanium to applications that need the strength of steel in a lighter package and lends titanium to be used in aircraft parts and other weight-dependent applications. The density of steel can be an advantage in certain applications such as in a vehicle chassis, but most of the time, weight reduction is often a concern.
The modulus of elasticity, sometimes referred to as Young’s modulus, is a measure of the flexibility of a material. It describes how easy it is to bend or warp a material without plastic deformation and is often a good measure of a material’s overall elastic response. Titanium’s elastic modulus is quite low, which suggests it flexes and deforms easily. This is partly why titanium is difficult to machine, as it gums up mills and prefers to return to its original shape. Steel, on the other hand, has a much higher elastic modulus, which allows it to be readily machined and lends it to be used in applications such as knife edges, as it will break and not bend under stress.
When comparing the tensile yield strengths of titanium and steel, an interesting fact occurs; steel is by-and-large stronger than titanium. This goes against the popular misconception that titanium is stronger than most other metals and shows the utility of steel over titanium. While titanium is only on par with steel in terms of strength, it does so at half the weight, which makes it one of the strongest metals per unit mass. However, steel is the go-to material when overall strength is the concern, as some of its alloys surpass all other metals in terms of yield strengths. Designers looking solely for strength should choose steel, but designers concerned with strength per unit mass should choose titanium.
Elongation at break is the measure of a test specimen’s initial length divided by its length right before fracturing in a tensile test, multiplied by 100 to give a percentage. A large elongation at break suggests the material “stretches” more; in other words, it is more prone to increased ductile behavior before fracturing. Titanium is such a material, where it stretches almost half its length before fracturing. This is yet another reason why titanium is so difficult to machine, as it pulls and deforms instead of chips off. Steel comes in many varieties but generally has a low elongation at break, making it harder and more prone to brittle fracture under tension.
Hardness is a comparative value that describes a material’s response to scratching, etching, denting, or deformation along its surface. It is measured using indenter machines, which come in many varieties depending upon the material. For high-strength metals, the Brinell hardness test is often specified and is what is provided in Table 1. Even though the Brinell hardness of steel varies greatly with heat treatment and alloy composition, it is most of the time always harder than titanium. This is not to say that titanium deforms easily when scratched or indented; on the contrary, the titanium dioxide layer that forms on the surface is exceptionally hard and resists most penetration forces. They are both resistant materials that work great when exposed to rough environments, barring any additional chemical effects.
Source article from: Thomasnet
Steel
Perfected during the onset of the 20th century, steel has quickly become the most useful and varied metal on Earth. It is created by enriching elemental iron with carbon, which increases its hardness, strength, and resistance. Many so-called alloy steels also use elements such as zinc, chromium, manganese, molybdenum, silicon, and even titanium to improve its resistance to corrosion, deformation, high temperatures, and more. For example, steel with a high level of chromium belongs to the stainless steels, or those which are less prone to rusting than other alloys. Since there are many kinds of steel, it is hard to generalize its specific properties, but our article on the types of steel gives a good introduction to the various classes.
To speak generally, steel is a dense, hard, yet workable metal. It responds to the heat treatment strengthening process, which allows even the simplest of steels to have variable properties based on how it was heated/cooled. It is magnetic and can conduct both heat and electricity readily. Most steels are susceptible to corrosion due to its iron composition, though the stainless steels address this weakness to some degree of success. Steel has a high level of strength, but this strength is inversely proportional to its toughness, or a measure of resilience to deformation without fracture. While there are machining steels available, there are other steels that are difficult, if not impossible, to machine due to their working properties.
It should be clear that steel can fit a lot of different jobs: it can be hard, tough, strong, temperature or corrosive resistant; the trouble is that it cannot be all these things at once, without sacrificing one property over the other. This is not a huge problem though, as most steel grades are inexpensive and allow designers to combine different steels in their projects to gain compounding benefits. As a result, steel finds its way into nearly every industry, being used in automotive, aerospace, structural, architectural, manufacturing, electronics, infrastructural, and dozens more applications.
Titanium
Titanium was first purified into its metallic forms in the early 1900s and is not as rare as most people believe it to be. In fact, it is the fourth most abundant metal on Earth, but is difficult to find in high concentrations or in its elemental form. It is also difficult to purify, making it more expensive to produce than to source.
Elemental titanium is a silver-grey non-magnetic metal with a density of 4.51 g/cm3, making it almost half as dense as steel and landing it in the “light metal” category. Modern titanium comes either as elemental titanium or in various titanium alloys, all made to increase both the strength and corrosion resistance of the base titanium. These alloys have the necessary strength to work as aerospace, structural, biomedical, and high-temperature materials, while elemental titanium is usually reserved as an alloying agent for other metals.
Titanium is difficult to weld, machine, or form, but can be heat-treated to increase its strength. It has the unique advantage of being biocompatible, meaning titanium inside the body will remain inert, making it indispensable for medical implant technology. It has an excellent strength-to-weight ratio, providing the same amount of strength as steel at 40% its weight, and is resistant to corrosion thanks to a thin layer of oxide formed on its surface in the presence of air or water. It also resists cavitation and erosion, which predisposes it towards high-stress applications such as aircraft and military technologies. Titanium is vital for projects where weight is minimized but strength is maximized, and its great corrosion resistance and biocompatibility lend it to some unique industries not covered by more traditional metals.
Comparing Steel & Titanium
Choosing one of these metals over the other depends upon the application at hand. This section will compare some mechanical properties common to steel and titanium to show where each metal should be specified (represented in Table 1, below). Note that the values for both steel and titanium in Table 1 come from generalized tables, as each metal widely varies in characteristics based on alloy type, heat treatment process, and composition.
The first striking difference between titanium and steel is their densities; as previously discussed, titanium is about half as dense as steel, making it substantially lighter. This suits titanium to applications that need the strength of steel in a lighter package and lends titanium to be used in aircraft parts and other weight-dependent applications. The density of steel can be an advantage in certain applications such as in a vehicle chassis, but most of the time, weight reduction is often a concern.
The modulus of elasticity, sometimes referred to as Young’s modulus, is a measure of the flexibility of a material. It describes how easy it is to bend or warp a material without plastic deformation and is often a good measure of a material’s overall elastic response. Titanium’s elastic modulus is quite low, which suggests it flexes and deforms easily. This is partly why titanium is difficult to machine, as it gums up mills and prefers to return to its original shape. Steel, on the other hand, has a much higher elastic modulus, which allows it to be readily machined and lends it to be used in applications such as knife edges, as it will break and not bend under stress.
When comparing the tensile yield strengths of titanium and steel, an interesting fact occurs; steel is by-and-large stronger than titanium. This goes against the popular misconception that titanium is stronger than most other metals and shows the utility of steel over titanium. While titanium is only on par with steel in terms of strength, it does so at half the weight, which makes it one of the strongest metals per unit mass. However, steel is the go-to material when overall strength is the concern, as some of its alloys surpass all other metals in terms of yield strengths. Designers looking solely for strength should choose steel, but designers concerned with strength per unit mass should choose titanium.
Elongation at break is the measure of a test specimen’s initial length divided by its length right before fracturing in a tensile test, multiplied by 100 to give a percentage. A large elongation at break suggests the material “stretches” more; in other words, it is more prone to increased ductile behavior before fracturing. Titanium is such a material, where it stretches almost half its length before fracturing. This is yet another reason why titanium is so difficult to machine, as it pulls and deforms instead of chips off. Steel comes in many varieties but generally has a low elongation at break, making it harder and more prone to brittle fracture under tension.
Hardness is a comparative value that describes a material’s response to scratching, etching, denting, or deformation along its surface. It is measured using indenter machines, which come in many varieties depending upon the material. For high-strength metals, the Brinell hardness test is often specified and is what is provided in Table 1. Even though the Brinell hardness of steel varies greatly with heat treatment and alloy composition, it is most of the time always harder than titanium. This is not to say that titanium deforms easily when scratched or indented; on the contrary, the titanium dioxide layer that forms on the surface is exceptionally hard and resists most penetration forces. They are both resistant materials that work great when exposed to rough environments, barring any additional chemical effects.
Source article from: Thomasnet