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1、焊缝射线照相底片的评判规律一、 探伤人员要评片，四项指标放在先,底片标记齐又正,铅字压缝为废片。 二、 评片开始第一件,先找四条熔合线，小口径管照椭圆，根部都在圈里面。 三、 气孔形象最明显,中心浓黑边缘浅，夹渣属于非金属,杂乱无章有棱边。 四、 咬边成线亦成点，似断似续常相见，这个缺陷最好定，位置就在熔合线。 五、 未焊透是大缺陷，典型图象成直线，间隙太小钝边厚，投影部位靠中间. 六、 内凹只在仰焊面,间隙太大是关键，内凹未透要分清，内凹透度成弧线. 七、 未熔合它斜又扁，常规透照难发现，它的位置有规律,都在坡口与层间。 八、 横裂纵裂都危险，横裂多数在表面，纵裂分布范围广,中间稍宽两端尖.
2、 九、 还有一种冷裂纹，热影响区常发现,冷裂具有延迟性,焊完两天再拍片。 十、 有了裂纹很危险，斩草除根保安全，裂纹不论长和短，全部都是级片。 十一、 未熔和也很危险，黑度有深亦有浅,一旦判定就是它,亦是全部级片. 十二、 危害缺陷未焊透，级焊缝不能有，管线根据深和长，容器跟着条渣走*. 十三、 夹渣评定莫着忙,分清圆形和条状，长宽相比3为界，大于3倍是条状。 十四、 气孔危害并不大，标准对它很宽大，长径折点套厚度，中间厚度插入法。 十五、 多种缺陷大会合，分门别类先评级，2类相加减去，3类相加减级。 十六、 评片要想快又准，下拜焊工当先生，要问诀窍有哪些，焊接工艺和投影。 注：*四项指标系底
3、片的黑度、灵敏度、清晰度、灰雾度必须符合标准的要求。 *指单面焊的管线焊缝和双面焊的容器焊缝内未焊透的判定标准.Radiograph Interpretation - WeldsIn addition to producing high quality radiographs, the radiographer must also be skilled in radiographic interpretation。 Interpretation of radiographs takes place in three basic steps which are (1） detection， （2
4、） interpretation， and (3) evaluation. All of these steps make use of the radiographers visual acuity。 Visual acuity is the ability to resolve a spatial pattern in an image. The ability of an individual to detect discontinuities in radiography is also affected by the lighting condition in the place o
5、f viewing, and the experience level for recognizing various features in the image。 The following material was developed to help students develop an understanding of the types of defects found in weldments and how they appear in a radiograph。DiscontinuitiesDiscontinuities are interruptions in the typ
6、ical structure of a material. These interruptions may occur in the base metal, weld material or ”heat affected” zones。 Discontinuities， which do not meet the requirements of the codes or specification used to invoke and control an inspection, are referred to as defects.General Welding Discontinuitie
7、sThe following discontinuities are typical of all types of welding。Cold lap is a condition where the weld filler metal does not properly fuse with the base metal or the previous weld pass material (interpass cold lap)。 The arc does not melt the base metal sufficiently and causes the slightly molten
8、puddle to flow into base material without bonding。 Porosity气孔is the result of gas entrapment in the solidifying metal. Porosity can take many shapes on a radiograph but often appears as dark round or irregular spots or specks appearing singularly, in clusters or rows。 Sometimes porosity is elongated
9、 and may have the appearance of having a tail This is the result of gas attempting to escape while the metal is still in a liquid state and is called wormhole porosity. All porosity is a void in the material it will have a radiographic density more than the surrounding area.。Cluster porosity链状气孔is c
10、aused when flux coated electrodes are contaminated with moisture。 The moisture turns into gases when heated and becomes trapped in the weld during the welding process. Cluster porosity appear just like regular porosity in the radiograph but the indications will be grouped close together。Slag inclusi
11、ons夹渣 are nonmetallic solid material entrapped in weld metal or between weld and base metal. In a radiograph， dark, jagged asymmetrical shapes within the weld or along the weld joint areas are indicative of slag inclusions.Incomplete penetration （IP) or lack of penetration (LOP）未焊透occurs when the we
12、ld metal fails to penetrate the joint. It is one of the most objectionable weld discontinuities。 Lack of penetration allows a natural stress riser from which a crack may propagate. The appearance on a radiograph is a dark area with welldefined， straight edges that follows the land or root face down
13、the center of the weldment。 Incomplete fusion未熔合is a condition where the weld filler metal does not properly fuse with the base metal。 Appearance on radiograph： usually appears as a dark line or lines oriented in the direction of the weld seam along the weld preparation or joining area.Internal conc
14、avity or suck back内凹或吸入is condition where the weld metal has contracted as it cools and has been drawn up into the root of the weld. On a radiograph it looks similar to lack of penetration but the line has irregular edges and it is often quite wide in the center of the weld image。Internal or root un
15、dercut内部或根部咬边is an erosion of the base metal next to the root of the weld. In the radiographic image it appears as a dark irregular line offset from the centerline of the weldment。 Undercutting is not as straight edged as LOP because it does not follow a ground edge。External or crown undercut外部或顶部咬边
16、is an erosion of the base metal next to the crown of the weld. In the radiograph, it appears as a dark irregular line along the outside edge of the weld area. Offset ormismatch错边are terms associated with a condition where two pieces being welded together are not properly aligned。 The radiographic image is a noticeable difference in density between the two pieces。 The difference in density is caused by the difference in material th
