Alloy Elements City

Alloy Elements 9

Alloy Elements

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AlloyElements

Steel is an alloy ofiron, in other words it is composed of carbon and iron. There aremore than 3500 steel grades, each comprising distinct chemical,environmental, and physical properties. Properties of every steelgrade are determined by the amount of carbon, impurity levels, aswell as additional elements. Different forms of steel aremanufactured in accordance to the required properties for theirappliance. These properties are used by grades to differentiatesteel. Steel can be largely classified into four categories based ontheir composition of chemicals. These groups include carbon, alloy,tool, and stainless steels. For example, carbon steels have traces ofelements of alloys. They make up 90 percent of overall manufacturingof steel. Alloy steels comprise of such alloying elements such asmanganese, nickel, titanium, copper, aluminum, and chromium.Stainless steels encompass between 10 and 20 percent chromium.Lastly, tool steels comprise of cobalt, molybdenum, vanadium, andcobalt in varying quantities. This paper aims to identify and discusswhich alloying elements are fit for cutting tools, rail track points,cutlery or surgical instruments, and turbine blade in the tablebelow.

Alloy

Alloying Element %

C

Mn

Cr

Ni

Co

Mo

W

Nb

1

1.5

4.6

5.0

12.5

2

0.08

16.2

11.5

1.5

1.0

3

0.8

18.0

9.0

4

1.0

13

Alloy 1

Alloy1 is fit for cutting tools. It falls under a steel type called toolalloys. Tool alloys denote to a range of alloy and carbon steels,which are predominantly well suited for manufacturing of tools. Thereare six categories of tool steels, namely, cold-worked,water-hardened, high-speed, shock-resistant, special purpose, andhot-work. Alloy 1 belongs to the high-speed steel grade whosecommercial designation is HSS. The preference of a grade is based oncosts, hardness of required surface, shock resistance, toughnessrequirements, strength, and working temperature. The more severe thecondition of the service, for example, abrasiveness, loading, highertemperature, or corrosiveness, the higher the content of alloy aswell as consequent carbide amount required for tool steels(Szafrański 2005).

Toolsteels encompass four key elements of alloying, namely, chromium,tungsten, molybdenum, and vanadium. The dissolution rate of thesealloying elements into the iron’s austenite form the establishedhigh temperature steel performance (slower dissolution rate is betterbecause it manufactures a heat resistant steel)(Enomotoand Hayashi 2015). Thus, proper treatment of heat of the steels iscrucial for sufficient performance.

Effect of Key Alloying Elements onMechanical and Physical Properties

Increasedcarbon content strengthens and hardens the steel while a decrease inthe content of the carbon decreases the machinability, weldability,and ductility of the steels. Additions of chromium increaseresistance of corrosion and hardenability. Cobalt increases thestrength of high temperature and red hardness. Molybdenum promotesthe formation of fine grain as well as toughening during tempering(Szafrański 2005). The content of manganese is mostly kept low inorder to reduce chances of cracking during quenching of water.

Advantages and Disadvantages of HighSpeed Steel

Toolsteels’ suitability stems from their unique hardness, resistance todeformation and abrasion as well as their capacity to clasp cuttingedge during high temperatures. High-speed tool steels become verybrittle when heated and hard to design (Szafrański 2005).

Reason for Choosing Alloy 1 for Cutting Tools

Thereason for choosing alloy 1 for cutting tools is that it falls undertool steels. It comprises of 1.5 C, 4.6 Cr, 5.0 Co, and 12.5 W, whichare key elements in high-speed steel grade. This particularhigh-speed steel is a tungsten steel whose commercial designation isT1. High-speed steels are used to manufacture different cutting toolssuch as drills, tool bits, milling cutters, saw blades, gear cutters,jointer and planer blades (Szafrański 2005).

Alloy 2

Alloy2 is a form of a stainless steel and is fit for cutlery and surgicaltools. Its commercial designation is 300 series Austenitic grade.First, stainless steels contain different alloying elements accordingto composition and specific grade. Examples of alloying elementsinclude manganese, sulphur,carbon, nickel, chromium, phosphorous, nitrogen, molybdenum, copper,calcium, titanium,silicon, niobium, and cobalt. Stainless steels are divided into fivecategories, namely, ferritic, austenitic, martensitic, duplex, andprecipitation hardening. Ferritic steels comprise of chromium andsmall carbon amounts of less than 0.10 percent. Austenitic steels aremade from adding manganese, nitrogen, and nickel. Martensitic aremade from chromium though with higher levels of carbon, 1 percent.Duplex have a microstructure of nearly 50 percent ferritic and 50percent austenitic. Lastly, precipitation hardening are made fromcopper, aluminum, and niobium. Alloy 2 is a 300 series austeniticgrade because it comprises of chromium, nickel, nitrogen, andmolybdenum (Nomani et al. 2015).

Advantages and Disadvantages ofAustenitic Grades

Austeniticgrades are widely available and they have excellent cryogenictoughness. They also have excellent weldability and formability andgeneral resistance to corrosion. The disadvantages of austeniticgrades encompass work hardening may limit machinability andformability and limited endurance to cracking due to stress corrosion(Li et al., 2011).

Effect of Key Alloying Elements onMechanical and Physical Properties

Austeniticgrades cannot be hardened or strengthened through the treatment ofheat. However, they respond to different degrees to cold treatment asa mechanism for strengthening. Austenitic types have face centeredcube atomic arrangement (Enomoto and Hayashi 2015). They have uniqueproperties. Furthermore, mechanically, they are more impact andductile strong at cryogenic temperatures. A key physical property ofaustenitic grades is that they are nonmagnetic. Additionally, theypossess lower rates of thermal conductivity and elevated rates ofthermal expansion because of carbon content (Li et al., 2011).

Reason for Choosing Alloy 2 for Cutlery andsurgical tools

Alloy2 was chosen for cutlery and surgical tools because it comprises ofhigh levels of chromium and nickel and has small additions oftungsten and molybdenum. It also has a maximum of 0.08 carbon. Alloy2 belongs to a 300 series grade called 316 and is mostly used incutlery as well as high quality cookware (Li et al., 2011).

Alloy 3

Alloyis a stainless steel of a grade known as martensitic whose commercialdesignation is M410. It is fit for building turbine blades (Enomotoand Hayashi 2015). Martensitic is a type of stainless steel.Martensitic steel were the first to be commercially developed. Theyhave a high carbon concentration compared to others. They are plainform of stainless steels that contain 12 to 18 percent of chromium(Groover 2007).

Advantages and Disadvantages ofMartensitic Steels

A key advantage ofmartensitic steels is that they can be hardened through treatment ofheat. On the hand, some of the disadvantages of martensitic steelsare that they are not as corrosion resistant as austenitic andformable as ferritics. They also have limited weldability (Groover2007).

Effectof Key Alloying Elements on Mechanical and Physical Properties

Martensiticsteels can be hardened through treatment of heat. They containnickel, chromium, molybdenum, and carbon, which makes gives themhardened properties. They have increased carbon content that allowsto harden on cooling in water, oil, or air (Enomoto and Hayashi2015). Furthermore, depending on intended use and grade, ductility isenhanced through tempering. Martensitic steels are distinguished fromother steels by their hardiness and high strength. Martensitic aretempered to obtain useful mechanical properties such as a particulartoughness level (Groover 2007).

Reason for Choosing Alloy 3 for Turbine Blades

Alloy 3 comprises of ahigher content of carbon with high chromium content. Martensiticsteels are used to manufacture turbine blades because their hardenedand increased strength that is required of turbine blades (Groover2007).

Alloy 4

Alloy4 contains small concentrations of carbon and high concentrations ofmanganese. Commercial designation for carbon steel is T-1. Alloy 4 isfit for rail track points because of the high concentrated manganeselevels. Carbon steels can be defined as steels that contain less than0.5 percent of manganese and 0.5 percent silicon, while all othersteels are called alloy steels. Carbon steels are divided into fourgrades, namely, medium carbon steel, mildsteel, high carbon, and very carbon steels. Alloy 4 falls under ‘veryhigh carbon steels’ because of the high carbon and manganese levels(Degarmo et al., 2007).

Advantages and Disadvantages of VeryHigh Carbon Steels

Carbonsteels are affordable compared to other steels. They have naturallyincreased strength. Carbon steel base materials are cheaper than mostalloys in other steels. Carbon steel does not require frequentreplacements, which saves funds on repairs as well as components ofreplacement. Carbon steel are highly recyclable, thus it isenvironmentally friendly. Carbon steels are highly durable. They arepopular in construction and infrastructure applications. They areresistant to changes in pressure and harsh weather. They arenon-combustible as well as resistant to shocks. Lastly, carbon steelshave a naturally tensile strength. This indicates it is difficult tobreak or bend. Carbon steels have their disadvantages as well.Because of the high content of carbon, they are very brittle andhard, which indicates they are unlikely to bend under immensepressure, though have increased chances of breaking or snapping.Carbon is unattractive and heavy (Degarmo et al. 2007).

Effectof Key Alloying Elements on Mechanical and Physical Properties

Manganese is a de-oxidizer, thus itneutralizes the oxygen, which might be around from making carbonsteels. Manganese is more efficient when it is added in highconcentrations. For example, Hadfield’s steel has 12 to 14 percentof manganese and 1.0 percent of carbon. This steel has an excellentwear resistance, thus it is utilized for railway track points, stonecrushers, and rock drills (Degarmo et al. 2007).

Reasonfor Choosing Alloy 4 for Railway Tracks

Alloy 4 is an example ofa carbon steel and carbon steels are used for industrial andinfrastructure applications such as industrial machinery, structures,and tools, power plants, shipbuilding, and railwaytracks. Carbon steels are used in these applications because of theirhardness, shock resistance, and strength (Degarmo et al. 2007).

Conclusively, this paper hasdiscussed different types of steel alloys identifying some of theirapplications. In particular, it has identified and discussedwhich alloying elements are fit for cutting tools, rail track points,cutlery or surgical instruments, and turbine blade.It has established stainless steel are fit for cutlery and surgicalinstruments, tool steels for cutting tools, carbon steel for railtrack points, and lastly turbine blades are manufacture from a typeof a stainless steel as well.

References

Degarmo, E, Black, JT and Kohser, Ronald A(2007),&nbspMaterials and Processesin Manufacturing&nbsp(10th ed.),Wiley.

Enomoto, M, and Hayashi, K2015, `Simulation of the growth of austenite during continuousheating in low carbon iron alloys`,&nbspJournalOf Materials Science,20, AGRIS, EBSCOhost,viewed 14 November 2016.

Groover, MP (2007), Fundamentalsof Modern Manufacturing: Materials, Processes and Systems,3rd ed, John Wiley &amp Sons, Inc., Hoboken,&nbsp

Li, Y, Fan, C., Rong, L., Yan, D. and Li, X(2011), Hydrogen Embrittlement Resistance of Austenitic Alloys anndAluminium Alloys,&nbspActaMetallurgica Sinica, 46(11),pp.1335-1346.

Nomani, J, Pramanik, A,Hilditch, T, &amp Littlefair, G 2015, `Chip formation mechanism andmachinability of wrought duplex stainless steelalloys`,&nbspInternationalJournal Of Advanced Manufacturing Technology,80, 5-8, pp. 1127-1135, Academic Search Complete, EBSCOhost,viewed 14 November 2016.

Szafrański, A (2005), ‘Transport propertiesof some hydrogenated nickel-based alloys,’&nbspJournalof Alloys and Compounds, 404-406,pp.195-199.