Ie 348 Test 1: Materials

Engineering stress is defined as the force (F) applied to a material per unit area (Ao), represented by the formula sigma = F / Ao.

Engineering strain is defined as the change in length (L) of a material compared to its original length (Lo). The correct formula calculates this change in length divided by the original length, which is represented as e=(L-Lo)/Lo.

The correct formula for Modulus of Elasticity is E=sigma/e where E is the Modulus of Elasticity, sigma is the stress applied, and e is the strain experienced.

The yield point is the point at which a material under stress exhibits a significant increase in strain without an increase in stress. It is a critical characteristic that indicates the maximum stress a material can withstand without permanent deformation.

Tensile strength is calculated by dividing the maximum load (Fmax) by the original cross-sectional area (Ao) of the material.

In engineering mechanics, 'necking' refers to the portion of the elastic curve to the right of TS, indicating the point where the material begins to deform plastically.

Ductility refers to the ability of a material to plastically strain without fracture, and it can be measured by the amount of strain a material can endure before failure. This property is crucial in determining the suitability of a material for certain applications.

True stress-strain accounts for the actual changes in area or length of a material as it undergoes deformation, providing a more accurate representation of its behavior under load.

Toughness refers to the ability of a material to absorb energy before breaking. It is different from stiffness, maximum stress, and deformation resistance.

Work hardening, also known as strain hardening, is the process through which a metal becomes stronger as the strain applied to it increases. This is achieved by deforming the metal, leading to an increase in its strength and hardness.

When the true stress-strain of the plastic region of the curve is plotted against log-log time, it results in a linear relationship due to the nature of the materials in that region.

Hardness in materials refers to the resistance to permanent indentation and scratching. It also has a strong correlation with strength, making the material less prone to deformation under pressure.

When considering density and strength, aluminum is a preferable material due to its lightweight nature and strength. However, iron and steel are often chosen due to their lower cost compared to aluminum.

The correct order of strength for the metals listed is based on their respective tensile strengths and ability to withstand loading conditions. Aluminum, aluminum alloys, cast iron, steel, and titanium alloys are ranked in increasing order of strength, with titanium alloys being the strongest among the five.

Steel is primarily composed of Iron and Carbon, which give it its strength and other properties. The other alloy combinations listed are not typically used to create steel.

Hot hardness specifically refers to the ability of a material to maintain its hardness even when exposed to elevated temperatures, making it a desirable characteristic for materials used in high-temperature applications.

When a metal is strained, it usually undergoes strain hardening which increases its strength. However, if the metal is heated to a high temperature, it can then be deformed more easily without an increase in strength.

Recrystallization in the context of metalworking refers to the temperature at which metal does not undergo strain hardening when deformed. By understanding this concept, the efficiency of metalworking processes can be improved.

Hot working involves shaping metals at high temperatures to make it easier to deform and manipulate.

Annealing is a heat treatment process that involves heating a metal to a specific temperature, holding it for a certain time, and then slowly cooling it. It is done for various reasons as mentioned in the correct answer.

Martensite is a hard and brittle microstructure in steel that allows for high strength levels through strengthening mechanisms.

The eutectic temperature in an alloy system is always the lowest melting point, representing the specific composition at which the solid and liquid phases coexist in equilibrium.

Eutectoid is a reaction in which a single solid phase transforms into two different solid phases upon cooling, typically from a melt. On the other hand, eutectic is a reaction in which a liquid phase transforms into two different solid phases upon cooling.

Plain carbon typically displays a range of ductility levels (low, medium, high) with the overall trend of decreasing ductility as strength increases.

Low alloy steel contains a small percentage of another element (usually around 5%) in addition to iron and carbon, making it stronger and more durable than regular steel. This higher alloy content results in a higher cost compared to traditional steel.

High alloy steel is commonly referred to as stainless steel due to its high corrosion resistant properties attributed to the presence of chromium and nickel.

Carbon is added to stainless steel to increase its strength and hardness, but an excess amount can actually reduce corrosion resistance. The bonding of chromium and carbon can lead to a deficiency of free chromium, affecting the overall properties of the alloy. It is essential to maintain the right balance to achieve the desired properties of stainless steel.

Tool steels are specifically designed and manufactured to be highly alloyed for use in tools that require heat treatment to achieve optimal performance. They are not the same as low carbon steels, stainless steels, or cast iron, which serve different purposes.

Cast iron is a group of iron-carbon alloys that contain a high amount of carbon and silicon, resulting in low ductility. The most common types are grey, ductile, and white cast iron.