Solving Materials Problems: Electronic Configuration & Steel Microstructure

[jcsolis]

I am answering a take home test but I am stucked with two questions:

1) How does electronic configuration affects chemical reactivity?

2) Describe the microstructure of a piece of steel after roling in one direction to achieve 20% reduction by cold working

Homework Statement

Numbers are not given

Homework Equations

The Attempt at a Solution

I can´t find an answer in my book...so I am asking for your help guys..

Thanks

 

[Astronuc]

1) How does electronic configuration affects chemical reactivity?

The answer would be found in a textbook on introductory chemistry.

Think of the periodic table and the relationship of the atomic number Z to the number of electrons, and the resulting electronic structure. The valence electrons determine the types of bonds an element forms. Look at the alkali and alkaline Earth metals, as opposed to transitional metals, semi-metals, halogens and noble gases.

2) Describe the microstructure of a piece of steel after rolling in one direction to achieve 20% reduction by cold working

What happens when rolls a piece of steel with a permanent deformation which achieves 20% reduction (cold work)? What happens to the grains when they are compressed?

One consequence in the increase in dislocations in the metal. Dislocation density affects strength and ductility.

Also think about what happens in recrystallization.

 

[piercas]

1) The electronic configuration of an element refers to the arrangement of electrons in its atoms. This arrangement determines the chemical properties of the element, including its reactivity. The number and arrangement of electrons in the outermost energy level (valence electrons) determines how easily an element can gain, lose, or share electrons with other elements to form compounds. Elements with a full outer energy level, such as noble gases, are considered stable and have low reactivity. On the other hand, elements with incomplete outer energy levels, such as metals, tend to be more reactive as they try to gain or lose electrons to achieve a stable configuration. Therefore, the electronic configuration of an element directly affects its chemical reactivity.

2) When steel is cold worked, it undergoes plastic deformation, resulting in a change in its microstructure. The microstructure of steel is made up of grains, which are tiny crystals of the metal. These grains are formed during the solidification process of the steel and are randomly oriented. When steel is cold worked, the grains become elongated along the direction of deformation. This is due to the movement of dislocations within the grains, which causes the grains to elongate. This elongation results in a more compact and dense microstructure, with smaller grains and a higher number of grain boundaries. The 20% reduction in thickness by cold working results in a significant increase in the strength and hardness of the steel due to the increased number of grain boundaries, which act as barriers to dislocation movement. This also leads to an increase in the yield strength and tensile strength of the steel. Additionally, the cold working process can also result in the formation of new phases within the steel, such as martensite, which further contributes to its strength and hardness.