AWS B1.10M-B1.10 pdf free download

AWS B1.10M-B1.10 pdf free download.Nondestructive Examination of Welds.
4.1 Discussion of Discontinuities. The goal of nondestructive examination is to identify anomalies or irregularities for evaluation; irregularities as distinguished from the overall examination area. To the trained eye, irregularities will appear to“break” the relative uniformity or“continuity” of the examination area. Along with evaluation come considerations for accepting those discontinuities or rejecting them. A3.0 defines a discontinuity as“an interruption of the typical structure of a material, such as a lack of homogeneity in the mechanical, metallurgical, or physical characteristics. A discontinuity is not necessarily a defect.” It defines a defect as“a discontinuity or discontinuities that by nature or accumulated effect render a part or product unable to meet minimum applicable acceptance standards or specifications. The term designates rejectability.” For the purpose of this guide, reference will be made to detection of discontinuities without regard to the distinction between acceptance or rejection. Discontinuities may be found in the weld metal, heat- affected, and base metal zones of weldments made in the five basic weld joint types: butt, T-, corner, lap, and edge. The following subclause presents a partial list of discontinuities that may be encountered in the fabrication of metals by welding. When specific discontinuities are located in the weld metal, heat affected, or base metal zones, the abbreviations WMZ, HAZ, and BMZ, respectively, are used to indicate the location. 4.2 List of Discontinuities. The most common types of discontinuities in butt, T-, corner, lap, and edge joints are listed in Table I and depicted in Figures 1 through 10. Where the list indicates that the discontinuity is generally located in the weld, it may be expected to appear in almost any type of weld. Tungsten inclusions are an exception. Tungsten inclusions are found only in welds made by the gas tungsten are or plasma are welding processes.
Weld and base metal discontinuities of specific types are more common when certain welding processes and joint details are used (see Table 2). High restraint and limited access to portions of a weld joint may cause a higher than normal incidence of weld and base metal discontinuities. Each general type of discontinuity is discussed in detail in this clause. 4.3 Porosity [see Table 1 (1)月]. Porosity is a cavity type discontinuity formed by gas entrapment during weld solidification. The discontinuity formed is generally spherical, but it may be elongated. A common cause of porosity is contamination during welding. Generally, porosity is not considered to be as detrimental as other discontinuities, such as cracks or incomplete fusion. The rounded shape of porosity does not concentrate stress as much as sharp discontinuities like cracks or incomplete fusion. Porosity is an indication that welding parameters, welding technique, welding consumables, gas shielding, or joint fit-up are not being properly controlled for the welding process selected or that the base metal is contaminated or of a composition incompatible with the weld fller metal being used. Important information regarding the cause of the problem is provided by describing both the shape and orientation of individual pores or geometric array of adjacent pores. An example of this utility is the distinction between elongated porosity and piping porosity. Both have lengths greater than their width, but they differ because of their orientation with respect to the weld axis. They also differ in terms of how they are caused. By providing this additional detail, an inspector is giving more information than a standard will normally require, but it can be very helpful in determining what corrective action to take.AWS B1.10M-B1.10 pdf download.