A COMPARISON OF FATIGUE CRACK PROPAGATION IN INCONEL 625 AND 3.25 NICKEL STEEL

The United States Navy is interested in determining the feasibility of replacing the presently used copper-nickel stern tube and strut bearing sleeves on ship propeller shafts with a weld overlay of Inconel 625. This thesis investigates the suitability of an Inconel 625 weld overlay from the standpoint of fatigue crack growth resistance. It is now well known that microcracks can appear very early in the life of a structure subjected to fatigue, although they may grow very slowly in their early stages of life. The practical importance of this crack growth period is emphasized by the fact that in welded components, it is virtually impossible to produce material that is completely free of defects which may be the site of future fatigue cracks. In this study, the fatigue crack growth rates of Inconel 625 weld metal, Inconel 625 annealed plate and Navy specification Class 2 shaft steel were compared in air and artificial sea water. The results indicate that, from a fatigue crack growth standpoint, Inconel 625 weld metal is a satisfactory material, though application processes should be investigated to optimize grain structure.

• Corporate Authors:

  Massachusetts Institute of Technology

  Department of Ocean Engineering, 77 Massachusetts Avenue
  Cambridge, MA  United States  02139
• Authors:
  • Long Jr, T A
• Publication Date: 1972-6

Subject/Index Terms

• TRT Terms: Cracking; Fatigue cracking; High strength steel; Struts
• Old TRIS Terms: Stern tube bearings
• Subject Areas: Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00044171
• Record Type: Publication
• Source Agency: Massachusetts Institute of Technology
• Files: TRIS
• Created Date: May 11 1973 12:00AM