外文文献原文及译文外文文献原文及译文.doc

附录1 外文文献原文及译文 原文： An evaluation of NDT methods for the location and sizing of forging discontinuities In selecting an NDT method for flaw detection in forgings a number of variables must be considered: a) the type of discontinuity to be assessed; b) the method to be used for detection and evaluation, and c) the variables associated with the forging itself The variables in item a) will govern the location within the forging and its orientation with respect to a particular surface Item b) could include a considerable array of NDT methods, but for the purpose of this paper only the six most widely used are considered一visual testing (VT), penetrant inspection(PI), magnetic particle inspection(MI), eddy current testing (ET), radiographic inspection (RT) and ultrasonic inspection (UI). In the last item c) the component race include such things as condition, geometry access for inspection. Forging discontinuities The location of the discontinuity will have a significant influence on the selection of the NDT method to be used and they are therefore grouped into three categories, to aid this selection: 1. open to the surface: laps, seam, burst, slugs, cracks and inclusions 2. slightly subsurface: seam, stringers, inclusions and grain structure variations 3. internal: stringers, burst, lamination, grain structure, inclusions and piping A brief review of these terms may be helpful: Lap: folded metal, flattened into the surface but not fusing with it Seam: linear flaws due to oxidized blow holes or ingot splashes, which are elongated by hot working Burst: ruptures caused by failure of plastic deformation by processing at too low a temperature or excessive working of metal Stringers: a bar stock defect, due to non metallic inclusions being squeezed out into long and thin strings Lamination: planar defect aligned parallel to surface, originating in the original ingot from rolled out piping Cracks: transgranular failure, due to localized stresses resulting from non-uniform