# What Microstructure Results from Complex Cooling of 1.13% C Steel?

• yecko
In summary, based on the isothermal transformation diagram for a 1.13 wt% C steel alloy, a small specimen subjected to the given time-temperature treatments (rapid cooling to 650 degree celsius, holding for 3 s, rapid cooling to 398 degree celsius, holding for 25 s, then quenching) will result in the presence of cementite, medium pearlite, bainite, and martensite. This is because the curve of the transformation diagram passes through the regions of A+P, A+B, and M. While there is no specific label for cementite, it is still present in any form of microstructure.
yecko
Gold Member

## Homework Statement

Q10.20 Using the isothermal transformation diagram for a 1.13 wt% C steel alloy (Figure 10.39), determine the final microstructure (in terms of just the microconstituents present) of a small specimen that has been subjected to the following time–temperature treatments. In each case assume that the specimen begins at 920 degree celsius and that it has been held at this temperature long enough to have achieved a complete and homogeneous austenitic structure.

(e) Rapidly cool to 650 degree celsius, hold at this temperature for 3 s, rapidly cool to 398 degree celsius, hold for 25 s, then quench to room temperature.Answer: Cementite, medium pearlite, bainite, and martensite

## Homework Equations

[/B]
the existence of “pearlite, bainite, and martensite” is because the curve went through the region of “A+P”, “A+B” and “M”.

## The Attempt at a Solution

(Same with “relevant equation” session)why would there be cementite?

The curve didn’t went through any other region, and there isn’t even a label indicating cementite (though there is C for proeutectoid cementite…)Thank you very much!

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Cementite in any form of micro-structure is still cementite.

## 1. What is "TTT Phase transformation"?

TTT Phase transformation refers to the Time-Temperature-Transformation diagram, which is a graphical representation of the relationship between time, temperature, and the resulting microstructure of a material during a phase transformation process. It is also known as an isothermal transformation diagram.

## 2. What is the importance of TTT Phase transformation in materials science?

TTT Phase transformation is important in materials science because it helps us understand and predict the microstructural changes that occur in a material at different temperatures and times. This information is crucial for designing and selecting materials with desired properties for specific applications.

## 3. How is the TTT Phase transformation diagram constructed?

The TTT Phase transformation diagram is constructed by conducting experiments in which a material is heated to a specific temperature and held for a certain amount of time, after which it is cooled at a constant rate. The resulting microstructure is then analyzed, and the data is plotted on a graph to create the diagram.

## 4. What factors influence the TTT Phase transformation of a material?

The TTT Phase transformation of a material can be influenced by several factors, including the composition and structure of the material, the starting temperature, the cooling rate, and any impurities present. These factors can affect the kinetics of the phase transformation and result in different microstructures.

## 5. How is TTT Phase transformation useful for industrial applications?

TTT Phase transformation is useful for industrial applications because it allows for the precise control and optimization of the microstructure and properties of materials. This is important for industries such as metallurgy, where the strength, ductility, and toughness of a material can greatly affect its performance in different applications.

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