Reference no: EM133147043

Metals Manufacturing - Studio Content

Studio Introduction

Phase transformations are an important aspect of metals manufacturing when high temperatures are involved (such as in casting or heat treating). A phase can describe either states of matter, such as liquid or solid (relevant in casting), or else different crystalline structures in a solid, such as b.c.c, body centred cubic or f.c.c, face centred cubic (relevant in heat treating steels or titanium alloys). Thus it is important to understand the important mechanisms in these phase transformations and their impact on microstructure and mechanical properties.

Studio tasks
In the following questions you are asked to use the data measured in the studios to plot or calculate values and then use observations and theory to answer questions.

Three steel grades were experimented with; the first has 0.02 wt.% Carbon, the second has 0.18 wt.% Carbon and the Third has 0.40 wt.% Carbon. The steels with 0.18 wt.% and 0. 0 wt.% Carbon were placed into an air furnace and then quenched into different media as per the table below. This resulted in 9 different specimens (All results:

1. Using an iron-carbon phase diagram, calculate the expected phases and volume fraction of each phase at room temperature for the a) the 0.02 wt.% C steel b) the 0.18 wt.% C steel and c) the 0.40 wt.% steel. Draw the equilibrium microstructure you would expect at room temperature for each steel.

2. Present the hardness values in a table with an appropriate measure of uncertainty for the steels with 0.18 wt.% and 0.40 wt.% Carbon.

3. Examine the optical micrographs of all 9 etched specimens collected from the Lab (both steels and each heat treating condition). Draw the microstructure using a pen or pencil for each condition and clearly label ALL the phases, constituents or defects that are visibly present. You may have to use your hardness values and literature to assist you in making the determination of the present phases.

4. Explain the difference in microstructure between the "As Cast" and the two "As Received" steels.

5. Explain the difference in microstructure between the different cooling rates and the two steels - use reference to time-temperature transformation or continuous cooling transformation curves in your answer. Assume that the oil quench cooling rate is between 50 - 100 °C/sec and that the water quench rate is ~ 300 °C/sec; You can use the pyrometer vs time data for your air quench rate.

6. Suggest the optimal heat treatment for 0.40 wt.% steel to produce what you consider to be the best combination of properties for a Hammer. The answer might not be one of the heat treatments or conditions that were used in the studio. Explain your answer and use any literature required to justify it.

Studio

Extrusion

Atomic diffusion and free energy are both key fundamental concepts that underpin the way the microstructure within a metal responds to temperature. Since the properties of a metal are so reliant on the microstructure, it is important to understand how these diffusion and free energy can explain microstructural development.

Studio tasks

In the following questions you are asked to use theory from the classes (and literature if needed) to prepare theory-based answers to the following questions. You can use diagrams to assist with your answers if you like.

1. Reflecting on the Extrusion demo video and lecture content, what effect does;

a. preheating the billet have on the extrusion process?

b. the extrusion speed have on the properties and the quality of the extrusion?

2. Calculate the extrusion force required for a 28 cm radius billet if our final profile with a 20 cm radius for each of the following materials and temperatures:

a. 1100 Aluminium at 450°C

b. Beryllium at 900°C

c. Copper at 600°C

3. Explain why quenching is often used in the manufacturing and/or heat treatment of steels. Part of your explanation should include how this effects the final mechanical properties of this material.

Studio - Roll forming

Roll forming is a cold forming process in which flat sheet metal is incrementally bent by a series of rolls to obtain the desired shape. In this process, the bending radius of the tool decreases in every station to form the smallest desired radius in the last station. This process enables forming of high strength steels with limited tensile ductility to smaller bend radii compared to other processes like simple bending and stamping. However, the smallest formable radius of a material in this process is limited by its ductility. This implies that a formability measure for a material should be identified to determine the extent to which a material can be formed in the process.

Studio tasks

In the following questions you are asked to use theory from the classes (and literature if needed) to prepare theory-based answers to the following questions. You can use diagrams to assist with your answers if you like.

1. A 2.4 mm thick martensitic steel sheet can be bent over a tool radius of 5.2 mm. Calculate the bend ratio.

2. Calculate the minimum inner bending radius if the bending strain just before fracture is 0.327.

3. What are the major advantages and disadvantages between of roll forming a sheet metal product or stamping a sheet metal product?

4. What material properties affect Springback?

5. Calculate the Ks value of a stainless steel that has an initial bend radius of 2 mm, a final bend radius of 3 mm and a thickness of 1.60 mm.

Attachment:- Metals Manufacturing.rar