Peening operations

Abrasives is a term given to various materials with different physical formats (such as aggregate, grains, shot, particles bonded with an adhesive, and so forth) that are used to wear down stufaces to desired dimensions or surface finishes or for some other purpose. They may be used in their raw state, such as with shot or glass in shot or glass-bead peening operations. Or they may be used in conjunction with adhesives and fillers to make belts, wheels, and tool surfaces. 

Shot peening results in considerable increase of the operating and service life of constructions affected by dynamic loads. 

Mechanical effects can be produced by mechanical cleaning methods. Wire brushing a surface to remove contaminants may work-harden the part s surface. Tumbling operations may result in a shot-peen effect dependent upon the material, or it may remove plated surfaces. 

Recently, a combined pack aluminizing and ball peening process was developed by the authors group (collaborative research at USTB and UOA) to produce nanostmctured aluminide intermetallic coatings on carbon steel, stainless steel and/or Ni-based superalloys at a relatively low operating temperature (440-600°C) and in a short time (15-120 min) (see Fig. 7.3) (Zhan et al, 2006a,... 

Example case history 1. A gas turbine s compressor rotor developed blade tensile stresses while in operation that would quickly lead to failure. The OEM specified that a glass-bead peening process needed to be conducted all over the surface of the... 

During one of the turbine s overhauls, the repair facility mistakenly only glass-bead peened one side of the compressor blades. Two engines failed during operation before the error was discovered. It was not known with which turbines the error had been made. The only way to determine this without doubt was to destructively test the compressor blades with X-ray diffraction. The entire fleet of engines that the overhaul shop had handled with that SB included had to be recalled. 

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