ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The body-centered tetragonal (BCT) structure in quenched Fe-C steels is usuallyillustrated to show a linear change in the c and a axes with an increase in carbon content from 0to 1.4%C. The work of Campbell and Fink, however, shows that this continuous linearrelationship is not correct. Rather, it was shown that the body-centered-cubic (BCC) structure isthe stable structure from 0 to 0.6 wt%C with the c/a ratio equal to unity. An abrupt change inthe c/a ratio to 1.02 occurs at 0.6 wt%C. The BCT structure forms, and the c/a ratio increaseswith further increase in carbon content. An identical observation is noted in quenched Fe-Nsteels. This discontinuity is explained by a change in the transformation process. It is proposedthat a two-step transformation process occurs in the low carbon region, with the FCC firsttransforming to HCP and then from HCP to BCC. In the high carbon region, the FCC structuretransforms to the BCT structure. The results are explained with the Engel-Brewer theory ofvalence and crystal structure of the elements. An understanding of the strength of quenchediron-carbon steels plays a key role in the proposed explanation of the c/a anomaly based oninterstitial solutes and precipitates
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/14/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.215.pdf
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