Finding Values Using Fe-C Diagram for Materials Engineering Assignment

In summary: The microhardness of the three swords will be around 375, 550, and 900.The carbon content of the three swords will be 4.3%, 0.8%, and 0.18%.The three swords will be heated to 1150, 725, and 1493 degrees Celsius, respectively.
  • #1
Jimmojo
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Summary:: Need help with finding values using Fe c diagram

Hi, I'm doing a materials engineering assignment. In the assignment they require us to make 3 swords being given martenistic steel bars with dimensions 40x100x1000mm with a composition of Fe-0.76wt.%C (eutectoid composition). Sword A has final microhardness (HV) value of between 350-400(avg375), sword B between 550-700(avg625) and sword C between 900-950 (avg925). Based on these we are to determine and justify proper processes for making the sword.
what I am struggling with is:
Using the Fe-c diagram, I am not sure what the carbon percentage is for each sword and what temperature it would be on the diagram, based on the HV value. I've seen some answers with:
Sword A: 4.3% and 1150 degrees Celsius
Sword B: 0.8% and 725 degrees Celsius
Sword C: 0.18% with 1493 degrees Celsius,
But I don't understand where they come from. Would anyone be able to explain?
Thanks a lot
 
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  • #2
Welcome to PF.
You will need to link to the phase diagram you are using for the assignment, or post it to this thread. We will then be able to communicate more clearly.
 
  • #3
This is the diagram. I am just unsure how they have gotten where A, B and C are on the diagram and what the heating temperature for each sword should be. I have looked around online and can't find a relationship between the microhardness (HV value) and the Carbon percentage or a relationship between the HV value and the required temperature. If anyone could explain how based on the values we have we're supposed to find the heating temperatures and carbon percentages on the Fe c diagram.
Also a bit confused as to why the A, B and C values on this diagram from an answer I've looked at has the swords at different carbon percentage values even though the task specified the materials to be of Fe -0.76wt.%C composition.
If anyone could explain, I'd really appreciate it.
thanks a lot
16026433231075541436523045008679.jpg
 
  • #4
One sword will be wrought, worked in air to reduce the carbon content. One will be baked in carbon to increase the carbon content. One will be left with carbon as it was.

There are approximate equivalencies between the various hardness scales.
You know graphite is soft, while ferrite is hard.
Find hardness information for the iron-carbon alloys.

Find those compositions on your diagram, close to the initial C% composition.
Mark three points on the diagram at those compositions and temperatures.
 

1. What is a Fe-C diagram?

A Fe-C diagram, also known as an iron-carbon diagram, is a graphical representation of the relationships between the percentage of carbon and the temperature of a steel alloy. It is used to determine the phases and microstructures that form as a result of different heat treatments.

2. How is a Fe-C diagram used in materials engineering?

A Fe-C diagram is used in materials engineering to determine the appropriate heat treatment for a specific steel alloy in order to achieve desired properties, such as strength, hardness, and ductility. It also helps engineers understand the effects of carbon content and temperature on the microstructure of a steel alloy.

3. What are the different phases shown on a Fe-C diagram?

The different phases shown on a Fe-C diagram include ferrite, austenite, cementite, and pearlite. Ferrite is a soft, ductile phase with low carbon content, while austenite is a high-temperature phase with high carbon content. Cementite is a hard, brittle phase with high carbon content, and pearlite is a mixture of ferrite and cementite.

4. How do you use a Fe-C diagram to find the values for a specific steel alloy?

To find the values for a specific steel alloy using a Fe-C diagram, you must first determine the carbon content and temperature of the alloy. Then, locate the point on the diagram where the two values intersect. This point will correspond to a specific phase or microstructure, which can then be used to determine the properties of the alloy.

5. What are the limitations of using a Fe-C diagram in materials engineering?

While a Fe-C diagram is a useful tool for understanding the behavior of steel alloys, it does have some limitations. It assumes ideal conditions and does not take into account impurities or other alloying elements that may affect the microstructure. Additionally, it is only applicable to steel alloys and cannot be used for other types of materials.

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