Steel Metal
Part B.
After discovering that steel is the most preferred metal for engineering, I am more than curious to know about the various types of steel and how each of these types is made, and the modification steel has to undergo as well as establish the various reasons engineers prefer steel to other metals. I have discovered that there are more than 3000 different grades of steel, the grade of steel is determined by the amount of carbon and all the other alloys in the steel metal and the way that the steel has been processed (Baufield, 2019). I have also learned that steel is graded as a way of classification and there are four types of steel metal Carbon, Alloy, Stainless, and Tool.
I have gathered that carbon steel is the most produced type of steel and accounts for 90% of the steel produced. This type of steel has traces of other elements besides the two most prominent elements of steel, iron, and carbon (Baufield, 2019). This type of metal is further subdivided into three subgroups based on the carbon in the metal, these sub-groups are; low carbon steels which have about 0.3% of carbon, medium carbon steel which has a slightly higher amount of carbon that ranges from 0.3% to 0.6%, the last subgroup of carbon steel, high carbon steel has a slightly higher percentage of carbon that is above 0.6% (Baufield, 2019). I have also learned that most carbon steel metals contain Manganese. The low carbon steel is the most used metal from the three subgroups. The most unique thing about steel from this subgroup is that it is not hardened by heat instead its hardened state is achieved through cold work (Baufield, 2019). Carbon steel has relatively low strength, despite this, they have a high ductility that makes them the most preferred for machining, welding and they come at a relatively low cost.
In most occasion, high strength and low alloy steel fall under the classification of low-carbon steels, however, they contain other elements to include, copper, molybdenum, nickel, and vanadium (In Chinese Society for Metals (CSM), & In Chinese Academy of Engineering (CAE), 2016). The high strength of these metals is achieved through heat treatment. They also have a high ductility which makes them formable and machinable. After comparing these metals to low carbon steel, I found out they are slightly more resistant to corrosion than low carbon steels. In the automobile industry low carbon steel is used to make body (Matmatch, n.d).
Medium carbon steel has mechanical properties that are improved via heat treatment. These type of carbon metals also has a martensitic microstructure. Heat treatment of these metals can only be done on very thin sections of the metals (Matmatch, n.d). When hardened, medium-carbon steel has greater strength than low carbon steels, however, I discovered that these strengths come at the expense of ductility and toughness. Since these metals have high strengths and are resistant to wear, this type of carbon steel is used to make rail tracks, machinery parts, train wheels, and crankshafts (Matmatch, n.d). High Carbon steel is the hardest and toughest of the carbon steel metals, these metals also have the lowest ductility. I have learned that from the three subgroups of carbon metals they are the most hardened and tempered. High carbon steel is used to make cutting tools and high strength wires.
The second classification of steel metal that I am interested in exploring is the alloy steel metal. Alloy steel metals have alloy elements to include nickel, copper, chromium, and aluminum (Tuttle, 2018). From what I have gathered these other elements are added to the steel composition to increase the strength, hardness, toughness and wear resistance of the carbon steel metal (Tuttle, 2018). Allow steel metals are further subdivided into low alloy steel and high alloy steel. I have also gathered that the most accepted boundary between low and high allow steel is 5% (Tuttle, 2018). I feel like it is important to clarify that in the oil and gas sector alloy steel used is low allow steel. The difference between carbon steel and allow steel is the additional chromium and vanadium that is added in alloy steel (Tuttle, 2018).
The Carbon metal is alloyed to change the microstructure and the mechanical properties to form alloy steels. There are more than 15 elements that are mixed with carbon steel to produce different grades of alloy steels. Some of these elements include aluminum when used as an alloying element it removes phosphorous, Sulphur and oxygen. When silicon is used as an alloying element it increases magnetism of the steel and strength. Manganese as an alloying element is used to increase high-temperature strength, harden the metal and increase the ductility of the alloy metal. These additional elements are added with a focus on modifying the steel properties and make them more suitable for specific applications (Tuttle, 2018). It has also come to my realization that alloy steels have extensive uses in sectors to include, automobiles, machinery and equipment, and railway and road construction.
In the construction industry alloy steels are used to hold firmly large modern structures to include, bridges, airports, and skyscrapers (Tuttle, 2018). They provide the strength required to support large structures. Small items to include nails, screws, and bolts used in the construction of large structures are made from alloy steel.
Stainless steel contains chromium that ranges from 10-20%, chromium is the main alloying element used in making this type of steel highly resistant to corrosion (Baddoo, 2008). I have gathered that stainless steel is most preferred for use in medical equipment, to make pipelines, cutting tools and to make machinery and equipment in the food processing industry. Stainless steel contains a higher percentage of chromium and a relatively low amount of carbon. To increase oxidation and corrosion resistance elements to include nickel, titanium, aluminum, sulfur, and selenium are added (Baddoo, 2008). During production, most stainless steel is melted in electric-arc and oxygen furnaces.
It has also come to my realization that there are more than 100 grades of stainless steel, however, there are five classifications of stainless steel, these classifications include, austenitic, ferritic, martensitic, precipitation hardening and duplex. Tool steel is a commonly used type of steel in engineering (Baddoo, 2008). I have learned that this type of steel is resistant to deformation and flattening as a result of its hardened nature. Tool steel is also resistant to wear and breakage. Tool steel is carbon steel and alloy steel that are well suited to be used in making tools (Baek, et al., 2019). They are also suitable for use when shaping other materials as a result of their hardened nature.
Steel is the most commonly used metal in the field of engineering and this has been evidenced by the above discussion. I have discovered that the use of steel in the engineering field dates back to many centuries and has continued to evolve over the years. Today over 75% of the steel used in the construction and engineering sector has been developed in the last 20 years (In Chinese Society for Metals (CSM), & In Chinese Academy of Engineering (CAE), 2016). Following a close examination of data recorded by the World Steel Association the total amount of steel produced in the world amounted to 1808 million tons in 2018 and over 50% of this steel was used in the construction and engineering industry.
Part C
Conclusion
In conclusion, steel is one of the most important metals used in the construction industry, steel is most preferred because of its characteristics to include toughness and durability. Steel has a high melting point which makes its temperature resistant. Steel is extensively used in the construction and engineering industry and the automobile industry. Steel is flexible and can meet the requirements of different projects in infrastructure. Steel is produced in a basic oxygen furnace where various amounts of steel carp are mixed with flux and melted at extremely high temperatures. The use of steel to make equipment sparked my interest and drove me to study steel even further. I used to think that three was only one type of steel, however, I have discovered that there are four types of steel that are further subdivided into other categories. At the end of the research, I am well aware that every type of steel serves a different purpose according to its characteristics. I am now fully aware that all the other types of steel are a product of carbon steel and other elements are added to modify its structure and chemical composition. Research into steel metal has proved to be very insightful and has helped me replace some of the myths I had on steel with more factual information.
References
Baddoo, N. R. (2008). Stainless steel in construction: A review of research, applications, challenges and opportunities. Journal of Constructional Steel Research, 64(11), 1199- 1206
Baek, G. Y., Shin, G. Y., Lee, K. Y., & Shim, D. S. (2019). Mechanical Properties of Tool Steels with High Wear Resistance via Directed Energy Deposition. Metals, 9(3), 282.
Baufield, M., (2019). What Are the Different Grades of Steel? Retrieved from; https://www.meadmetals.com/blog/steel-grades
In Chinese Society for Metals (CSM),, & In Chinese Academy of Engineering (CAE),. (2016). HSLA Steels 2015, Microalloying 2015 & Offshore Engineering Steels 2015: Conference Proceedings.
Matmatch. (n.d). Carbon Steel: Properties, Production, Examples and Applications. Retrieved from; https://matmatch.com/learn/material/carbon-steel
Tuttle, R. (2018). Alloy Steels.
