Phase Transformation in Quenching a AISI 4140 Steel Bar

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Phase Transformation in Quenching a AISI 4140
Steel Bar
Guofang Zhou zhou2001_at_iit.edu T. Calvin
Tszeng tszeng_at_iit.edu
July 18th, 2003
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Project 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

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T/CS Installation
27 in length, horizontally quenched in polymer
Close-up of Embedded and Surface Thermocouples of
4140 Cylinder
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Temperature History
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FEM 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

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Results

• HTC V. TIME

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Comparison of Temperature History at the
Geometrical Center
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Phase Transformation History at the Geometrical
Center
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Microstructure from Optical Microscopy
100 mm
Magnification 400
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Discussion

• Predicted phase content
• 8 martensite, 14 pearlite and 78 bainite
• In the micrograph
• white area austenite ferrite
• black area bainite martensite

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CT diagram
Metal Progress, 1964

• ASM, 1977

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Jominy Test Simulation

• Jominy Bar

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

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Temperature 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

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Experiment 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
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Further 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