Title: Phase Transformation in Quenching a AISI 4140 Steel Bar
1Phase Transformation in Quenching a AISI 4140
Steel Bar
Guofang Zhou zhou2001_at_iit.edu T. Calvin
Tszeng tszeng_at_iit.edu
July 18th, 2003
2Project Review
Objective
- Demonstrate the ability to predict accurately the
thermal profiles and microstructure evolution
history in cylinders of AISI 4140 steels by
combining the FEM analysis and surface mounted
thermocouples.
Strategy
- Identify the necessary data for modeling the
quenching process - Obtain cooling curves at the surface of the 4140
steel forging - Perform inverse calculation and FEM analysis
- Validate the model
3T/CS Installation
27 in length, horizontally quenched in polymer
Close-up of Embedded and Surface Thermocouples of
4140 Cylinder
4Temperature History
5FEM Calculation
- Data Input
- Geometry, Process Specifications, Thermal
Properties - Phase transformation data from TTT diagram
- Temperature history measured from the surface
T/Cs - Inverse Calculation Control
- Results Analysis
- Heat transfer coefficient vs. locations, time,
temperature - Comparison of temperature history
- Microstructure / temperature vs. location,
time, temperature
6Results
7Comparison of Temperature History at the
Geometrical Center
8Phase Transformation History at the Geometrical
Center
9Microstructure from Optical Microscopy
100 mm
Magnification 400
10Discussion
- Predicted phase content
- 8 martensite, 14 pearlite and 78 bainite
- In the micrograph
- white area austenite ferrite
- black area bainite martensite
11CT diagram
Metal Progress, 1964
12Jominy Test Simulation
HTC Graphs
- Ref
- Tszeng, T.C. and Saraf, V., ASME J. of Heat
Transfer, 2003, Vol. 125 P1-10. - Buchmayr, B., and Kirkaldy, J.S., 1990, ASME J.
Heat Transfer, 8, pp. 127-136
13Temperature at different locations
- Austenization temperature at 860 C and 835 C
- HTC are different
14- At 1 second, the temperature drop at 1/32
- Starting Temperature
15Experiment Plan
- Normalize
- Machine
- Install TCs
- Austenite
- Quench
TC the center of the end surface, 1/8, 1/4,
1/2, 1 and 2 from the quench end
16Further Plan
- Perform Jominy Test
- Compare the measured temperature and compare with
those in the literature - Obtain the HTC for comparison
- Look into the microstructure
- Ref
- Metal Progress, Jan. 1964, pp. 100-104
- ASM International, Steels Heat Treatment and
Processing Principles. 1989