DEVELOPMENT OF AN ULTRASONIC METHOD FOR DETERMINATION OF GRAIN SIZE IN CAST STEEL

SCATTERING OF AN ACOUSTIC WAVE BY SPHERICAL OBSTACLES WHOSE DIAMETERS ARE MUCH SMALLER THAN THE WAVELENGTH AND WHOSE SEPARATIONS ARE SUCH THAT NO MULTIPLE SCATTERING OCCURS HAS PROVEN TO BE A REASONABLE MODEL FOR PREDICTING THE BEHAVIOR OF SCATTERED ULTRASONIC ENERGY BY CAST STEEL SPECIMENS, EACH OF A DIFFERENT GRAIN SIZE. ACCORDING TO THE MODEL, A PLOT OF THE DETECTED SCATTERED INTENSITIES ON SEMILOG GRAPH PAPER VERSUS THE ASTM GRAIN SIZE NUMBER SHOULD GIVE APPROXIMATELY A STRAIGHT LINE. THE WORK REPORTED HEREIN WAS UNDERTAKEN TO DETERMINE THE RELATIONSHIP BETWEEN ULTRASONIC SCATTERING AND FERRITE GRAIN SIZE AND USE IT TO EVALUATE NONDESTRUCTIVELY IMPORTANT MECHANICAL PROPERTIES OF THE STEEL. THE EXPERIMENT WOULD ALSO PROVIDE A VERIFICATION OF THE THEORETICAL APPROACH. A DUAL TRANSDUCER HOLDING DEVICE WAS DEVELOPED WHEREBY ULTRASONIC SHEAR WAVES WERE TRANSMITTED THROUGH THE MATERIAL AT A FIXED ANGLE, WHILE THE SCATTERED ENERGY WAS RECEIVED BY A SIMILAR TRANSDUCER FROM THE SAME SIDE OF THE SPECIMEN. THE PROBES WERE 10 MHZ WITH AN INCIDENT ANGLE OF 60 DEGREES. THE SONIC PATH WAS VARIED FROM 1.5 IN. TO 2.0 IN. BY A MICROMETER SCREW CONNECTING THE TWO TRANSDUCERS. THE SAMPLE MATERIAL CONSISTED OF FIVE RADIOGRAPHICALLY SOUND BLOCKS (3 IN. BY 3 IN. BY 6 IN.) CUT FROM A CAST CARBON STEEL PLATE. FERRITE GRAIN SIZES, ASTM NUMBERS 3, 5, 6, 7, 8, WERE PRODUCED BY HEATING THE MATERIAL AT 2200, 2000, 1900, 1700 AND 1650 DEGREES F, RESPECTIVELY, FOLLOWED BY FURNACE COOLING. RESULTS SHOW THE SCATTERED ENERGY INCREASES AS THE GRAIN SIZE DECREASES WITHIN THE RANGE TESTED. THIS TECHNIQUE IS CAPABLE OF DISTINGUISHING GRAIN SIZES ONE ASTM NUMBER APART IN THIS STEEL. THESE RESULTS SEEM TO BE IN FAIR AGREEMENT WITH THE THEORY. /AUTHOR/

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00255327
• Supplemental Notes:
  • Vol 28, No 12, PP 271-276, 3 FIG, 1 TAB, 4 PHOT, 16 REF
• Authors:
  • Digiacomo, G
  • Ohlstein, G
  • Jones, W J
• Publication Date: 1970-12

Media Info

• Serial:
  • Materials Evaluation
  • Publisher: American Society for Nondestructive Testing
  • ISSN: 0025-5327

Subject/Index Terms

• TRT Terms: Acoustic waves; Acoustics; Cast steel; Dissipation; S waves; Scattering; Shear strength; Shear stress; Sieve analysis; Sound; Sound; Steel; Ultrasonic tests; Wave motion
• Uncontrolled Terms: Shear transfer
• Subject Areas: Energy; Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00217047
• Record Type: Publication
• Files: TRIS
• Created Date: Jan 18 1971 12:00AM