Mô tả chung về ứng dụng :
Nứt do xâm thực hydrô có thể xuất hiện trong thép dễ bị ảnh hưởng trong môi trường nước có chứa Sunfua hydrô. Đó là dạng nứt có liên quan đến hydrô và có thể có hai hình thái phân biệt:

Ultrasonic Testing in the Foundry Industry

Application: This note contains a general overview of ultrasonic nondestructive testing applications in the foundry industry, including thickness gaging, flaw detection, and nodularity testing.

Background: The art of casting metal into specific shapes goes back thousands of years, but it is only in recent decades that modern ultrasonic NDT tools have been available to help insure product integrity. In ancient times, a foundryman might tap a casting with a hammer to judge its quality by the sound of the ring. Today, microprocessor-based instruments that also utilize sound waves can provide much more information about the hidden internal structure of both ferrous and nonferrous castings. Ultrasonic thickness gages can be used to measure the wall dimensions of hollow castings, ultrasonic flaw detectors

High Temperature Ultrasonic Testing

Background: Although most ultrasonic flaw detection and thickness gaging is performed at normal environmental temperatures, there are many situations where it is necessary to test a material that is hot. This most commonly happens in process industries, where hot metal pipes or tanks must be tested without shutting them down for cooling, but also includes manufacturing situations involving hot materials, such as extruded plastic pipe or thermally molded plastic immediately after fabrication, or testing of metal ingots or castings before they have fully cooled. Conventional ultrasonic transducers will tolerate temperatures up to approximately 50° C or 125° F. At higher temperatures, they will eventually suffer permanent damage due to internal disbonding caused by thermal expansion. If the material being tested is hotter than approximately 50° C or 125° F, then high temperature transducers and special test techniques should be employed.

This application note contains quick reference information regarding selection of high temperature transducers and couplants, and important factors regarding their use. It covers conventional ultrasonic testing of materials at temperatures up to approximately 500° C or 1000° F. In research applications involving temperatures higher than that, highly specialized waveguide techniques are used. They fall outside the scope of this note.

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