5.7. Name the four alloying elements that have the greatest effect on the properties of steels.
Boron improves harden ability, without the loss of (or even with some improvement in) mach inability and formability.
Calcium deoxidizes steels, improves toughness, and may improve formability and merchantability.
Carbon improves harden ability, strength, hardness, and wear resistance; it reduces ductility, weldability, and toughness.
Cerium controls the shape of inclusions and improves toughness in high-strength, low-alloy steels; it deoxidizes steels.
5.8. What are trace elements?
A chemical element present only in minute amounts in a particular sample or environment is called trace element. Residual elements are also known as trace elements.
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How do stainless steels become stainless?
Primarily their corrosion resistance, high strength and ductility, and high chromium content characterize stainless steels. They are called stainless because in the presence of oxygen (air) they develop a thin, hard adherent film of chromium oxide that protects the metal from corrosion (passivation). This protective film builds up again in the event that the surface is scratched.
QUALITATIVE PROBLEMS
5.20. Explain why continuous casting has been such an important technological advancement.
The inefficiencies and the problems involved in making steels in the traditional form of ingots are alleviated by the continuous-casting process, which produces higher quality steels at reduced costs. Conceived in the 1860s, continuous or strand casting was first developed for casting nonferrous metal strips. The process now is used widely for steel production, with major productivity improvements and cost reductions.
5.27. In Table 5.8, D2 steel is listed as a more common tool and die material for most applications. Why is this so?
Because it has high resistance to wear and cracking.
REVIEW QUESTIONS
6.1. Given the abundance of aluminum in the earth’s crust, explain why it is more expensive than
Sulfur goes back to the ancient times but it was called brimstone. In 1979, a French chemist named Antoine Lavoisier recognized sulfur was an element and added it to his list of elements. The element sulfur is considered a nonmetal and is the 10th most abundant element in the universe. On the periodic table sulfur is in group sixteen and it is a representative element. Sulfur has an atomic mass of 32.07 with an atomic number of 16. There are three energy levels for sulfur the first energy level is two, the second energy level is eight, and the third energy level is six.
...: Optimizing the austenite content and hardness in 51200 steel, J Mater Eng and Perform 2001; 10(1): 14-21.
The extraordinary power of the steel industry to shape the life of its communities and the people in them remain...
Very small amounts of Indium are occasionally added to gold or platinum alloys to make them harder. It is also added to solders*, it reduces the melting point of some and strengthens others; it also prevents other solders from breaking down easily.
The home building industry became widely aware of steel as a potential alternative in 1993. Steel makers, suppliers, manufacturers and even some builders were quick to rally around this new material. However, the "newness" of steel has a...
Rationale: This question ties in with the second level of Webb’s DOK because it deals with cause and effect. Also, the students are involved in metal processing.
Bessemer process is the method for making high quality steel quickly and cheaply by blowing air into molten iron to remove impurities. Steel’s uses are numerous and widespread, and it is used in industries from agriculture to technology. “… [Henry Bessemer] invented the Bessemer converter and the so called Bessemer process, from which molten iron could be transformed into high-quality steel quickly and in large quantities” (Finnigan 114). The Bessemer process for creating steel has had a massive effect on our culture, economy, and geography.
The micro hardness of the prepared samples were obtained by using a Vickers Micro hardness Tester (Model : Leco LV 700, USA). 5 readings were taken for each sample to calculate the average hardness. An indentation load of 5gf was used. After calculating the average hardness for each sample, mean variance and standard deviation (S.D.) was calculated to check the consistency of the data.
Steel is both the most widely used and most recycled metal material on earth From stainless and high temperature steels to flat carbon products, steel's various forms and alloys offer different properties to meet a wide range of applications. For these reasons, as well as the metal's combination of high strength and a relatively low production cost, steel is now used in countless products.
It is used with copper to form brass, and it is hard and brittle in it's natural state, less dense than iron and used to make many alloys.
Iron is this starting point for steelmaking which has performed as a backbone to the advancement of modern technology and is vital to the upbringing of the future. It acts as the predominant reason for the industrial revolution. The foundation that is iron, more industrially known as Cast Iron has been given the second honour as it is the one of the cheapest materials for engineering, when taken to molten temperatures it gains the ability to be cast into intricate shapes. Cast Iron has been sub-divided into 5 different classes when the composition is changed or tampered with. Each of these classes have different properties but in comparison with Steel which also has its grades ranging from low to high grade carbon steel which are just alloys of purified iron with carbon and hints of other metal elements such as Manganese and Nickel so the production of Steel products differs only slightly from the commercial production of Iron. Steel which is the easily formed, cheap and yet strong and tough allowing for it to be extremely versatile creating products ranging from paperclips to reinforcing elements in the construction of buildings and skyscrapers.
Stainless steel is a type of alloy that has a very strong lattice structure (an arrangement/ shape of the crystals or other objects) which in some case can be more beneficial than others depending on the type of application it may be used for. In many cases this structure will make the material more suited to being used in engineering applications such as tools for instance a hammer (stainless steel alloys) , also they can be used for gears, engines, electrical motors and hydraulic systems because the structure makes the material so strong. So when the arrangement of the structure is as above it makes the overall material even stronger which makes it a good for all the applications stated above. I believe its strength and durability are its main properties as these are commonly needed in the engineering industry, although it is also very well known to be used for its corrosion resistance as it is resistant to many types of corrosion. It is used for these properties because the components such as gears need to be strong in order to keep transferring and altering the rotary motion and torque exhibited in the machine that it may be used in, durable to withstand any loads or pressure put onto it and also corrosion resistance to give the components a bigger life span and increase its rate of work throughout its required use.
A steel is usually defined as an alloy of iron and carbon with the content between a few hundreds of a percent up to about 2 wt%. Other alloying elements can amount in total to about 5 wt% in low-alloy steels and higher in more highly alloyed steels such as tool steels and stainless steels. Steels can exhibit a wide variety of properties depending on composition as well as the phases and microconstituents present, which in turn depend on the heat treatment.
By adding up to 2%,of carbon it makes the steel tough and strong. Although it’s tough and strong, it is able to bend. To make sure that the metal doesn’t rust, it has a zinc coating on it. Iron is 26 on the periodic table,and considered an “transition metal,” meaning that it is ductile and malleable, and conduct electricity and heat. ... “Some other elements that are similar to iron are cobalt and nickel. They are the only elements known to produce a magnetic field.” Zinc is 30 on the periodic table and it is also a transition metal like iron. “The first iron used by humans is likely to have come from meteorites.” A meteorite is a meteor that survives its passage through the earth's atmosphere such that part of it strikes the ground. More than 90 percent of meteorites are of rock, while the remainder consist wholly or partly of iron and nickel. Meteors are believed to have been from the asteroid belt of Mars and
It is a complex metallurgical process in which liquid steel is cooled and shaped into semi-manufactures of desired dimensions. To achieve proper quality of cast steel, it is essential to control the metal flow and heat transfer during the casting process. In the continuous casting process, molten steel flows from a ladle, through a Tundish into the mould. It should be protected from exposure to air by a slag cover over each vessel and by ceramic nozzles between vessels. Once in the mould, the molten steel freezes against the water-cooled copper mould walls to form a solid shell. Drive rolls, lower in the machine continuously; withdraw the shell from the mould at a rate or “casting speed” that matches the flow of incoming metal, so the process ideally runs in steady state. Below mould exit, the solidifying steel shell acts as a container to support the remaining liquid. Rolls support the steel to minimize bulging due to the Ferro-static pressure. Water and air mist sprays cool the surface of the strand between rolls to maintain its surface temperature until the molten core is