Volume 4, Issue 2 (March 1976)
Salt Water and Hydrogen Sulfide Corrosion Fatigue of Work-Hardened, Threaded Elements
This work describes the results of a laboratory testing program undertaken to evaluate the merits of work-hardened, threaded machine elements when subjected to axial fatigue in the presence of a corrosive environment. The experimental apparatus is described, including details of the corrosive mediums. The most damaging corrosive medium consisted of a salt water solution through which hydrogen sulfide gas was bubbled. Lower corrosion fatigue damage was noted for aerated salt water and the least occurred for a deaerated salt water solution. The corrosion fatigue results are compared with results obtained in air for simple cut threads and fully cold-worked or rolled threads formed on AISI 8635 steel. The results show that at a life of 105 cycles the fully cold-worked threaded element had an endurance stress of 74 ksi (510 MPa) compared with 44 ksi (303 MPa) for the simple cut threaded element. Under the combined action of corrosion fatigue in the presence of a hydrogen sulfide saline solution these values were reduced to 46 ksi (317 MPa) and less than 20 ksi (138 MPa), respectively, which indicated that the fully cold-worked, threaded element was superior to all thread forms evaluated under a variety of environmental conditions.