As is well known, safety belts are mandatory requirements in most countries world wide for usage in automobile vehicles. The basic material used for the tongue component of a safety belt is usually low carbon steel. The tongue component after mechanical forming is subjected to heat treatment, pickling and plating of nickel and chromium. After plating, it is given a de-embrittlement treatment for the removal of any hydrogen embrittlement caused during the plating tratment. The tongue components are subjected to a 'load test', as part of the process/quality control, before thea are assembled. The presently investigated tongue component failed at a load less than that given in a specification. This paper describes the detailed microscopic examination carried out on the fractured tongue component (finished product). In order to determine if the defect (interdendritic porosity) was in any way related to process parameters, the raw material was also investigated. The basic objective of the present investigation is to determine the cause for the inferior properties of the tongue component. The results clearly point to the existence of very fine interdentritic porosity with incomplete solidification. The presence of these pores in the raw material is responsible for the inferior properties measured in the K12 tongue components. Casting practices should be implemented to avoid porosity. Perhaps, a slightly higher addition of chromium to the metal alloy should help, as it is more resistant to cavitation.
Investigation of fracture in a K12 tongue component
Bruchuntersuchung in einer K12-Zunge
Engineering Failure Analysis ; 9 , 1 ; 77-82
2002
6 Seiten, 7 Bilder, 6 Quellen
Article (Journal)
English