Copper alloys used for the manufacture of propellers may be classified into three groups: high tensile brasses (commonly called manganese bronzes), nickel aluminum bronzes, and manganese aluminum bronzes. The improved mechanical properties, including corrosion fatigue of the aluminum bronze alloys, enabled propellers to be made with thinner blade sections. This saving in weight and material has led to the adoption of these alloys and especially the nickel aluminum bronzes for the manufacture of most propellers fitted to large modern ships. Both eddy current and ultrasonic techniques are capable of detecting surface cracks in propeller bronzes. The degree of surface preparation required for the two techniques is similar, with ultrasonic techniques showing the greater benefit from further surface preparation. The main advantages of the ultrasonic technique are that large surface areas may be scanned more quickly than by eddy current techniques and that the required orientation of the probe is more easily maintained. Eddy current techniques have a slight advantage in sensitivity when the fine-grained alloys are examined and a much greater advantage when the coarse-grained manganese bronzes are to be inspected.

  • Corporate Authors:

    Welding Institute

    Abingdon Hall
    Cambridge CB1 6AL,   England 
  • Authors:
    • Porter, R
  • Publication Date: 1976

Media Info

  • Pagination: p. 28-30

Subject/Index Terms

Filing Info

  • Accession Number: 00149765
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Apr 27 1977 12:00AM