[Sci-all-l] Chemistry Seminar 5/3: Metallurgy

[Kam Dahlquist]

Title: Workability of Medium Carbon Forging Steel with Residual Copper

Time/location: May 3rd 1:30pm, room 318, Mudd Building,  Vassar College

Speaker: Dr. Chester J. Van Tyne, FIERF Professor, Department of Metallurgical
and Materials Engineering Colorado School of MinesGolden, CO  80401



Abstract:

With the increased use of electric furnace steel making, the amount of
residual copper in forging steels continues to increase.  Copper residual in
steels can cause surface cracking (often called hot shortness) during
deformation.  In this study, eight medium carbon steels with differing copper
contents, from 0.09% to 0.39% (by weight), were tested.  High strain rate
compression tests of pre-bulge samples were used to simulate forging
conditions.  The testing was divided into two stages:  Stage one, in which the
steels were oxidized at different temperatures from 1100 to 1200°C for 10 and
30 minutes.  Stage two, in which the steels were oxidized for 1, 3, 5, and 7
minutes at their critical temperature and deformed.  In the stage one testing,
steels oxidized for 10 minutes and deformed exhibited a critical temperature,
which decreased with decreasing copper content, from 1160°C for the steel with
the highest copper content to 1110°C for the steel with lowest copper
content.  In stage two testing, the results were less consistent.  The steels
with high copper content (0.32 to 0.39%) exhibited maximum cracking at shorter
times, while for the steels with medium copper content (0.21 to 0.30%) the
maximum cracking occurred at longer times.  A qualitative model based on
copper diffusion in steel and oxidation of the steel surface is proposed to
explain the results.

Contact: Sarjit Kaur
Chemistry Department
sakaur at vassar.edu

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Kam D. Dahlquist, Ph.D.
Assistant Professor of Biology

Vassar College, Box 516
124 Raymond Avenue
Poughkeepsie, NY 12604-0516

Tel: 845-437-5266
Fax: 845-437-7315
E-mail: kadahlquist at vassar.edu
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