Ultrasonic cleaning involves the use of high-frequency sound waves that is above the upper range of human heating, or about 18 kHz, to remove a variety of contaminants from parts immersed in aqueous media. This article describes the process, design considerations and the equipment in ultrasonic cleaning. The components used in the generation of ultrasonic wave include piezoelectric and magnetostrictive transducers that are used in ultrasonic generators and tanks. The effects of solution type and its temperature on the effectiveness of ultrasonic cleaning are also discussed.

This article describes the basic attributes of the most widely used metal surface cleaning processes to remove pigmented drawing compounds, unpigmented oil and grease, chips, cutting fluids, polishing and buffing compounds, rust and scale from steel parts, and residues and lapping compounds from magnetic particle and fluorescent penetrant inspection. The cleaning processes include emulsion cleaning, electrolytic alkaline cleaning, acid cleaning, solvent cleaning, vapor degreasing, alkaline cleaning, ultrasonic cleaning, and glass bead cleaning. The article provides guidelines for choosing an appropriate process for particular applications and discusses eight well-known methods for determining the degree of cleanliness of the work surface.

Passivation; pickling, that is, acid descaling; electropolishing; and mechanical cleaning are important surface treatments for the successful performance of stainless steel used for piping, pressure vessels, tanks, and machined parts in a wide variety of applications. This article provides an overview of the various types of stainless steels and describes the commonly used cleaning methods, namely, alkaline cleaning, emulsion cleaning, solvent cleaning, vapor degreasing, ultrasonic cleaning, and acid cleaning. Finishing operations of stainless steels, such as grinding, polishing, and buffing, are reviewed. The article also explains the procedures of electrocleaning, electropolishing, electroplating, painting, surface blackening, coloring, terne coatings, and thermal spraying. It includes useful information on the surface modification of stainless steels, namely, ion implantation and laser surface processing. Surface hardening techniques, namely, nitriding, carburizing, boriding, and flame hardening, performed to improve the resistance of stainless steel alloys are also reviewed.

This article focuses on the various techniques for removing contaminants in the surface preparation of steel for hot-dip coatings: wet cleaning methods, including alkaline cleaning, electrolytic cleaning, chemical pickling, and electrolytic pickling; flame cleaning and furnace-atmosphere techniques, such as Sendzimir oxidation/reduction method; other specialized methods, namely, fluxes, mechanical cleaning, and ultrasonic methods; or a combination of these.

Metal surfaces must often be cleaned before subsequent operations to remove unwanted substances such as pigmented drawing compounds, unpigmented oil and grease, chips and cutting fluids, polishing and buffing compounds, rust and scale, and miscellaneous contaminants. The article describes common cleaning processes, including alkaline, electrolytic, solvent, emulsion, molten salt bath, ultrasonic and acid cleaning as well as pickling and abrasive blasting. It also explains how to select the appropriate process for a given soil type and surface composition.

Fracture surfaces are fragile and subject to mechanical and environmental damage that can destroy microstructural features. This article discusses the importance of care and handling of fractures and the factors that need to be considered during the preliminary visual examination. It describes the procedures for sectioning a fracture and opening secondary cracks as well as the effect of nondestructive inspection on subsequent evaluation. The article provides information on the most common techniques for cleaning fracture surfaces. These techniques are dry air blast cleaning, replica stripping, organic-solvent cleaning, water-base detergent cleaning, cathodic cleaning, and chemical-etch cleaning.