Shot peening for the prevention of stress corrosion and fatigue cracking of heat exchangers and feedwater heaters
- Metal Improvement Co., Paramus, NJ (United States)
Shot peening is a cold working process where spherical media called shot bombards the surface of a part. Each piece of shot acts as a tiny peening hammer imparting to the surface a small dimple. In the process, the surface fibers of the material are yielded in tension. Below the surface, the fibers try to restore the surface to its original shape thereby producing a hemisphere of cold worked material highly stressed in compression. Completely overlapping dimples develop an even layer of residual compressive stress. Stress Corrosion Cracking (SCC) is a progressive fracture mechanism caused by the simultaneous interaction of a corrodent and a sustained tensile stress. The tensile stresses necessary for SCC are static and they may be residual and/or applied. Fatigue is also a progressive fracture mechanism caused by tensile stresses, but these stresses are dynamic and they usually lead to failure without the necessary simultaneous action of a corrodent. Compressive residual stresses such as those induced by controlled shot peening can be used to prevent or delay SCC and fatigue cracking, regardless of the materials or corrodents involved. This paper will deal with the theory and controls of the shot peening process, and with some of its applications on heat exchangers and feedwater heaters.
- Research Organization:
- Electric Power Research Inst. (EPRI), Palo Alto, CA (United States)
- OSTI ID:
- 227016
- Report Number(s):
- EPRI-TR-105876; CONF-9509192-; TRN: 96:001699-0018
- Resource Relation:
- Conference: EPRI feedwater heater technology symposium, Kansas City, MO (United States), 25-26 Sep 1995; Other Information: PBD: Dec 1995; Related Information: Is Part Of Proceedings: 1995 Feedwater heater technology symposium; PB: 270 p.
- Country of Publication:
- United States
- Language:
- English
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