ME381

Lab 1

Heat Treatment ReportName: Dawei Wang

Date: Oct. 19th 2015

1. On the CCT diagram for the 0.45% C steel shown below,sketch approximate cooling curves for

the annealed(furnace cooled),normalized(air cooled),oil quenched and water quenched steel samples.Use the following estimates of cooling times to go from the austenitizing

temperature(900℃) to room temperature(25℃) to determine the curves.Based on the CCT

diagram and cooling curves you sketched,predict the microstructure that should be present after

the four heat treatments(i-iv).Include a typical micrograph of the microstructure.

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Microstructure:

i:α+P

ii:α+P

iii:α+P+B+M

iv:M

Typical micrograph:

Pearlite:

Martensite:

Bainite:

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α-ferrite:

2. Calculate the average cooling rate(∆T/∆t) for each of the four cooling types(anneal,air,oil and

water) using the time estimates given in question #1.

i:∆T/∆t=(900-25)÷(24×3600)=0.01℃/s

ii:∆T/∆t=(900-25)÷(30×60)=0.486℃/s

iii:∆T/∆t=(900-25)÷30=29.17℃/s

iv:∆T/∆t=(900-25)÷2=437.5℃/s

3.Tabulate and plot hardness (form first 3 heat treatment+AR&AN )vs.heat treatment.What

happens to the hardness as the sample are cooled faster?

AverageHRB/HRC

long short

AC 86.73 71.23 HRB

OQ 98.65 76.23 HRB

WQ 47.60 39.15 HRC

AR 93.80 83.10 HRB

AN 77.33 61.86 HRB

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The sample become harder when cooled faster.

4.Plot hardness versus tempering temperature for the two steel compositions that were tempered

during lab.Include WQ as one of the temperatures.Discuss any trends you see in the data.

The hardness of the samples get smaller when the tempering temperature get greater.

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5.Was there any difference in the overall response to he heat treatment (hardness) between the two

types of steel? If so, explain what and why?Identify them.

Yes. The long steel is harder than the short steel in the overall response to the heat treatments.The

steels get harder when there are more percentage of C in them.So the long sample is AISI-SAE

1045,the short sample is AISI-SAE 1018.

AppendixHeat treatment of steel Data Sheet

Name(s):Dawei Wang

Date of Experiment:Otc. 19 th 2015

Group Number:1

My Heat Treatment(circle one):WT(300) short

H#1 H#2 H#3 Average Scale(HRB/

HRC)

31.0 32.3 30.9 31.4 HRC

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