Evaluation of railroad wheel steel with lamellar duplex microstructures using diffuse ultrasonic backscatter

Hualong Du, Cameron Lonsdale, John Oliver, Brent M. Wilson, Joseph A. Turner

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

The effects of lamellar duplex microstructure within grains that contain alternating phases of cementite and ferrite on ultrasonic scattering in railroad wheel steel are evaluated using a diffuse ultrasonic backscatter technique. A new singly scattered response (SSR) model that considers the lamellar duplex microstructure within grains is developed based on a previous SSR model. The results show that the amplitude of ultrasonic scattering decreases with decreasing lamellar space. Corresponding experiments are performed with 10 MHz and 15 MHz focused transducers by scanning both unquenched and quenched wheels. The experimental results show that the ultrasonic scattering amplitudes drop dramatically near the quenched tread surface, a result which is attributed to the creation of duplex microstructure (pearlite phase) within grains due to the quenching process. The lamellar spacing within grains increases progressively from the tread surface to the deeper locations due to the non-uniform cooling rate. The distribution of lamellar spacing within grains as a function of depth is quantified with the modified SSR model. Good agreement with optical microscopy is observed. The diffuse ultrasonic backscatter technique exhibits strong sensitivity to microstructure changes, an outcome that may be applicable for quality control during manufacturing.

Original languageEnglish (US)
Pages (from-to)331-340
Number of pages10
JournalJournal of Nondestructive Evaluation
Volume32
Issue number4
DOIs
StatePublished - Dec 2013

Keywords

  • Grain scattering
  • Microstructure characterization
  • Pearlite
  • Quenching
  • Ultrasound

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering

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