外文翻译--球墨铸铁的无损伤检测(编辑修改稿)

外文翻译--球墨铸铁的无损伤检测(编辑修改稿)内容摘要：

size of unacceptable indications are recorded. Indications, which subsequently may be removed by machining or by repair grinding according to table 4, shall not be recorded. Reporting All examinations shall be finished with a final report containing information as item No./type, inspector/date, examination results with information as mentioned in section and relevant sketches. Ultrasonic examination Equipment Ultrasonic instrument type pulseecho with presentation of Ascans on a CRTscreen or LCDdisplay. The instrument shall fulfil following requirements:  The time base shall be adjustable and permit selection of any range (screen length) within the working range of the instrument.  The instrument shall have an amplification range of at least 80 dB. The amplification must be adjustable in max. 2 dB steps with an accuracy of 1 dB.  The screen height linearity shall be better than 2%.  The instrument shall be capable to work within the frequency range of 6 MHz with single crystal probes as well as twin crystal probes and transmitterreceiver technique. Probes: Use of single crystal pression probes in the frequency range 1 4 MHz is normally preferred. In areas with stringent quality requirements scanning with twin crystal pression probes and angle probes may be prescribed. For wall thickness’ less than 20 mm a frequency of minimum 4 MHz shall be used for all probe types. For each standard ponent probe selection will appear from the specific CUSTOMER control instruction. Following probe types of manufacture Krautkr228。 mer or equivalent may be specified: Krautkr228。 mer Single crystal pression probes: MB2S, 2 MHz, 248。 10 mm B2S, 2 MHz, 248。 24 mm B1S, 1 MHz, 248。 24 mm Twin crystal pression probes: MSEB2, 2 MHz, 248。 10 mm SEB 20176。 , 2 MHz, 248。 24mm Couplant: Ultrasonic jelly, oil or paste. Surface condition General requirements to the surface finish of the specific control areas are described in the purchasing specification. The specified scanning surfaces in the control instruction shall have a condition, which ensures full coupling between the ponent and the sole of the probe. Possible irregularities may be ground flush to the surrounding surfaces. Calibration Digital ultrasonic instruments (. Krautkr228。 mer USN 52 or equivalent) with facilities such as auto adjustment of scale range and with preprogrammed DGS (AVG) curves for probes of same manufacture may be used. For such instruments calibration shall be performed in accordance with the routines described in the belonging manual and in accordance with following requirements: Scale range: The scale range is adjusted on a free edge of the item or using a calibration block of similar material. When using pression probes the scale range is adjusted using the back wall echo from a parallel surface on the item or from a calibration block of similar material. Sensitivity, pression probes: The back wall echo is set to 80 % of full screen height. Using the probe specific DGS –diagram the gain setting is adjusted to a sensitivity of the prescribed reference reflector at the relevant distance. Sensitivity, angle probes: Using angle probes the back wall echo from the radii39。 s on the IIW cal。