As we know steel pipe and steel plate mechanical performances depends on two aspects: One is the heat treatment type; Another one also the most important factor is the chemical elements effect to these steel material.
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Common chemical elements in steel is C, Mn, S, P, Si, V, Al, Cr, Mo, Ni, B. Considering on different type elements added and percentage properties, steel pipe and steel plate will shows different properties.
Such as for sour service pipe, Nace material pipe and fittings, it has a strict control with C, CEq, P, S, elements content.
Especially for Sulfur (S) content maximum at 0.002 for sour service pipe, but normal pipes S content maximum 0.015. This is a big difference.
The reason that why we need to control S to very less percentage, is S can push HIC happens; More S elements content and it will be more easy to generate HIC, Sulfer is an extremely harmful element.
What is Carbon (C) effect to steel material?
Carbon is the most important elements found in steel material. Steel material mechanical strength is directly connected with carbon content.
When the carbon element content increased, yield point and tensile strength increased, but the plasticity and impact reduced.
In case carbon content more than 0.23%, steel welding performance will get worse.
So in the low alloy steel structural, to get better welding performances, the carbon content usually less than 0.2%.
Meanwhile, high carbon content also reduces the air corrosion resistance of steel, and the high carbon steel in the open field is easy to rush.
In addition, carbon will increase the cold brittleness and aging sensitivity of steel.
Effect of phosphorus on steel made various effects in steel pipe and steel plate, in case on different concentrations.
Generally speaking, phosphorus is a harmful element in steel, it will increases the cold brittleness. It makes welding, pending performances get worse, and reduce the plasticity.
Therefore, the content of phosphorus in steel material is usually less than 0.045%, in high-quality steel material grade it is lower.
In higher steel grade, P content is 0.03 to 0.05, if P exceed 0.10 in low alloy high strength steels, it will increase the strength as well as improve the corrosive resistant performances. But the bad part is even the strength increased through P, it becomes brittle, ductility and toughness will reduce.
Effect of Sulfur in steel.
As we know, sulfur is a harmful element. It increase hot brittleness, reduce the ductility and toughness, cause cracks in forging and rolling.
Secondly, Sulfur is bad for welding performance, reduce the corrosion resistance. So it usually requires the sulfur content is less than 0.055%.
For the high-quality of steel, it requires S should be less than 0.04%. By adding 0.08-0.2% sulfur could improve cutting performance, which often called easy cutting steel.
So even S is a harmful element, if content less than 0.05%, it would be accept in general applications.
The effect of silicon (Si) in steel.
Si is used as a reducing agent and deoxidizer in steel making process, and usually contains 0.15-0.30% silicon in the sedative steel.
Silicon can improve the elastic limit of steel, yield point and tensile strength. So it has been widely used for spring steel.
In the quenched and tempered structural steel by adding 1.0-1.2% silicon, the strength will increased by 15-20%.
Silicon combines with molybdenum, tungsten, chromium and other composition, improve the corrosion resistance and anti-oxidation. So this combination of steel fit for producing the electrical heat-resistant steel.
But if increase silicon content the welding performance will reduce.
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Effect of manganese (Mn) on steel. In the steel making process, manganese is a good deoxidizer and desulfurization agent, the general steel containing 0.3-0.35% manganese. When adding more than 0.7% manganese in carbon steel it called manganese steel. Which not only have enough toughness, but also higher strength and hardness.
Manganese can improve the quenching and thermal processing performance of steel, such as 16 Mn alloy steel yield point is 40% more than A3 steel.
In addition, the steel which contains 11-14% manganese have high wear resistance, for the excavator bucket, ball mill liner. With manganese content increasing, corrosion resistance and welding performance reduces.
For example for API STANDARD 650, it requires ASTM A36 carbon (as rolled semi-killed or fully-killed) steel plate of all thickness shall have manganese content of 0.80% – 1.20% by heat analysis.
Above chemical elements are included in all of the general steel material.
On the other hand, Alloy steel pipe and plate chemical elements not only contains the normal chemicals like C (carbon), Si (silicon), Mn (manganese), P (phosphorus), S. But also with other alloy elements like Cr (chromium), Ni (nickel), Mo (molybdenum), tungsten, V (vanadium), Ti (titanium), Nb (niobium), Zr (zirconium), Co (cobalt), Al (aluminum), Co (copper), B (boron), rare earth and so on. Alloy steel pipe includes many types, commonly divided into low alloy, alloy and high alloy steel pipe, considering on how many types and percentages of the alloy chemical elements.
Effect of chromium (Cr) in steel pipe can improve strength, hardness, corrosive, wear resistance significantly. It is an important alloy element of stainless steel and heat-resistant steel pipe and plate. On the other side, it will reduce the plasticity and toughness.
Effect of Nickel (Ni) in steel pipe can improve strength meanwhile maintaining good plasticity and toughness. It has a high corrosion resistance to acid and alkali, anti-rust and heat resistant. But for it is a scarce resource, we should try to use other alloy elements instead of nickel-chromium steel.
Effect of molybdenum (Mo) can make steel grain refinement, improve the harden and thermal ability. It can maintain sufficient strength and creep resistance (deformation occurs under long-term stress at high temperatures calls creep). Adding molybdenum in structural steel can improve mechanical properties. In additional it can inhibit brittleness caused by quenching.
Effect of titanium (Ti) chemical elements in alloy steel pipe. It is a strong deoxidizer in steel. It can make the internal structure dense, fine grain strength; reduce aging sensitivity and cold brittleness. Moreover, it can improve welding performance. In the chrome 18 nickel 9 austenitic stainless steel, by adding the appropriate titanium could avoid internal grain corrosion.
Effect of vanadium (V) chemical elements in alloy steel pipe. It is an excellent deoxidizer for steel. Adding 0.5% V to the steel pipe material can refine the grain and improve the strength and toughness. Carbide forming by vanadium and carbon, in high temperature and high pressure can improve the ability of hydrogen corrosion resistance.
Effect of chemical elements tungsten in steel. As tungsten melting point is highest in metal discovered, the proportion is large, it is a kind of precious alloy elements. Tungsten with C together could form tungsten carbide which has a high hardness and wear resistance. By adding tungsten in tool steel will improve the red hardness and thermal strength significantly. This type of material could be used to cut steel and forging mold.
Effect of Nb (niobium) can refine the grain and reduce the steel overheating sensitivity and tempering brittleness, improve strength, but the plasticity and toughness will decrease. Adding niobium to the ordinary low-alloy steel, can improve the anti-atmospheric corrosion and high temperature hydrogen, nitrogen, ammonia corrosion. Furthermore, niobium improves welding performance. By adding niobium to austenitic stainless steel can prevents internal grain corrosion.
Cobalt is a rare precious metal, used for special steel and alloys, such as hot steel and magnetic materials.
Effect of Cu chemical elements in alloy steel pipe. Copper can improve strength and toughness, especially anti-atmospheric corrosion performance. The disadvantage is that in the hot processing is easy to produce hot brittle, more than 0.5% copper content will lead to plasticity reduces significantly. When the copper content is less than 0.50% has no effect on the welding performance.
Effect of chemical elements Al (aluminum) is an usual deoxidizer in steel. By adding a little amount of aluminum can refine grain, improve the impact toughness, such as 08Al steel. Aluminum also have anti-oxidation and corrosion resistance. Combined with chromium and silicon can improve the peeling resistance and high temperature resistance of steel. The disadvantages of aluminum is to influence the hot workability of the steel, the welding performance and the cutting performance.
Steel by adding trace amounts of boron can improve the steel’s compactness and hot-rolled properties, improve strength.
These elements are metals, but their oxides are like “soil”, so usually known as rare earth. The addition of rare earth to the steel can change the composition, morphology, distribution and properties of the inclusions in the steel, thereby improving the various properties of the steel, such as toughness, welding performance, and cold processing performance.
You don’t have to be an engineer to have heard of steel—this material is everywhere. It’s useful for heavy-duty construction tasks, and versatile enough to be made into cookware, too. This article will talk about steel’s features and uses, as well as the different types.
Steel is an iron and carbon combination with up to 2% carbon—but no more. Other elements can be (and are very often) added to the iron top of carbon, like manganese, chromium, and nickel, but in very small amounts to give it different benefits. Steel’s iron levels can reach 99% for carbon steel and mild steel. For the likes of stainless steel, like 304, you’ll find a lower percentage sitting around 70% iron. Other elements like cadmium, boron, and molybdenum are common additions, too. The trace amounts of different alloying elements are part of how steel is categorized and graded. Steel will last, on average, 100 years and it’ll stay rigid without swelling or creeping.
Steel is a strong metal that keeps its strength even under tension and heavy loads. It’s usable for a very long list of products and applications—and it’s a favorite of our customers at Xometry. Steel came to be in India thousands of years ago in 400 BCE and it has since developed into an alloy with numerous elements that make it the durable and common material manufacturers choose to use again and again. Here’s what it looks like:
Most steel types are machinable—with free-cutting steels being the easiest to work with—and easy to weld, too. Some are a little harder to weld with, but it’s still doable with a few specialized welding processes. When you put it up against other metals, you’ll notice steel has a lower thermal and electrical conductivity value, which makes it great for shielding against heat. More than 60% of steel gets recycled globally, and it’s fortunately an easy material to recycle and even reuse again. Steel is made by smelting through either a blast furnace or an electric arc furnace. The first method uses iron ore and a type of coal called coke, which has had its impurities removed. This gets fired by air and doused with lime to create the metallic material needed. You then end up with pig iron, which gets processed through a direct oxygen furnace that’ll create molten steel.
When using an electric arc furnace, you’ll fire the iron ore with natural gas in a direct reduction furnace, then you’ll send it to an electric arc furnace. In here, submerged electrodes will form hot arcs between one another and melt down the metal, and this is where you’d add in the alloying elements. After this, the molten steel is cast, rolled, shaped, then processed in any manner of ways, such as annealing or temperament, depending on what it’s needed to do. Unless it has the right alloying elements in it or is treated properly, steel tends to corrode more easily than other metals. It’s a heavier material than others (such as polycarbonate or plastics), which means it doesn’t usually work in all situations, especially when weight is a priority—like in aerospace. It also is one of the pricier materials, particularly grades that have been treated or made for specialty uses.
There are so many ways that steel can be used and, since it shows its face in many different sectors, it’s hard to list them all out. Just a few examples include tools, bridges, cars, trains, ships, beams, packaging, surgical instruments, medical implants, carabiners, pylons, sports equipment, motors, and generators. Here is an example of a part that can be made from steel.
Products that are designed to stay outside, or spend a lot of time outdoors and subject to various weather conditions (not only rain and snow, but sun rays, too), are often made from this weathering steel. Its chromium, nickel, and copper help this weather-resistant metal form an oxidized layer to keep corrosion away.
With around 2–3.5% silicon in its composition, electrical steel is used by electricians and contractors for wiring, motors, transformers, and other electrical needs.
While this is a type of tool steel, it’s particularly made for fast-moving power tools that can handle high pressure and speeds, and hot temperatures. To make it strong and durable, tungsten and molybdenum are included, and it is heat treated, too.
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