Effect of sulfide inclusion morphology and pearlite banding on anisotropy of mechanical properties in normalized C-Mn st
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I.
INTRODUCTION
A
previous study examined the influence of sulfide inclusions and pearlite content on the anisotropy of mechanical properties in a series of hot-rolled 0.1 and 0.2 pct carbon, 1.0 pct manganese steels containing either 0.004 or 0.013 pct sulfur with and without rare-earth additions. 1 It was found that both globular and stringered sulfide inclusions had a detrimental effect on reduction of area, shelf energy, and transition temperature. Their effect was particularly evident in deterioration of through-thickness properties and was much more severe for stringered inclusions than for globular inclusions. However, the effect of pearlite banding in the 0.2 pct carbon steels on anisotropy of mechanical properties was difficult to assess because of the problem in separating inclusion and banding contributions. Previous work also showed that a short-time, hightemperature normalizing treatment was capable of removing pearlite banding in a 0.25 pct carbon, 1.5 pct manganese steel, 2 which made it possible to compare mechanical properties in specimens that differed only in pearlite banding. Although the normalizing treatment removed pearlite banding, it did not completely remove the pattern of alloy microsegregation in the steel. 2 Because of the short time of the high-temperature normalizing treatment, inclusion morphology was assumed to be the same in the banded and nonbanded specimens. To gain further insight into the deleterious effects of inclusions and pearlite banding on anisotropy of tensile ductility and notch toughness, specimens of the 0.2 pct carbon steels used in the previous study I were given a short-time, hightemperature normalizing treatment for removal of pearlite banding. These specimens were then normalized a second W.A. SPITZIG is Associate Research Consultant with United States Steel Corporation, Research Laboratory, MS 59, 125 Jamison Lane, Monroeville, PA 15146. Manuscript submitted February 8, 1982. METALLURGICAL TRANSACTIONS A
time, but at a lower temperature, to reduce the grain size, after which they were compared with specimens that received only the lower temperature normalizing treatment. The inclusion characteristics in the steels in the banded and nonbanded conditions were analyzed by using automatic image analysis on the scanning electron microscope.
II.
MATERIALS AND PROCEDURES
The chemical compositions of the steels used in this study are given in Table I along with the number designation for reference throughout this paper. The preparation and processing of these steels has been described previously.1 Longitudinal and transverse tension and Charpy V-notch specimens of each steel were machined from the half- and quarter-width locations of the one-inch-thick plates and at half-and quarter-thickness locations. Through-thickness specimens were machined from specimen blanks cut from sections made by welding extensions of A514 steel to the top and bottom surfaces of sections cut from the half-and quarter-width positions from the plates of each steel. All the tension specim
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