The defects of welded joints can be classified according to various criteria: shape, size, location in the weld, the reasons of education, the degree of danger, etc. The best known is the classification of defects, the recommended standard for interstate GOST 30242-97, "Defects in connection with fusion welding of metals. Classification, identification and determination " . Under this standard, the defects of welded joints are divided into six groups:
- cavities, pores, fistulas, cavities, craters;
- incomplete and lack of penetration;
- violation of weld shape - undercuts, grooves shrinkage, excess convexity, excess proplava, afloat, displacement, sinters, burn marks, etc.;
- other defects.
According to GOST 30242-97 crack is lack of adhesion caused by local rupture of the seam or weld zone, which may arise as a result of cooling loads or actions.
Depending on the orientation of the crack can be divided into
- longitudinal (oriented parallel to the axis of the weld) - numbered 101, the letter of Ea;
- transverse (oriented perpendicular to the axis of the weld) - 102, Eb;
- radial (radiating from one point) - 103, E.
- placed in the crater of the weld - 104, Ec;
- separate group - 105, E;
- branched group - 106, E;
- microcracks (1001), detected by physical methods is not less than 50 tikratnom increase.
- uniformly distributed over the weld seam - 2012;
- located cluster - 2013;
- located Chain - 2014.
To also include cavities cavities (202, R) and craters (2024, K). Piping (GOST 30242-97) - a cavity which is formed as a result of shrinkage during solidification. crater called nezavarennaya piping at the end of the weld bead.
Solids (300) - is a solid metallic foreign substances or non-metallic origin, remaining in the weld metal. Acute-angled inclusions are called inclusions with at least one acute angle. Types of solids:
- slag inclusions (301, Ba) - linear (3011), separated (3012), others (3013);
- flux of (302, G) - linear (3021), separated (3022), others (3023);
- oxide inclusions (303, J);
- metallic inclusions (304, H) - Tungsten (3041), copper (3042), other metal (3043).
- on the lateral surface (4011);
- between the rollers (4012);
- at the root of the weld (4013).
Violation of the weld shape (500) - is the deviation of the external surfaces of the weld geometry or connections from the specified value. For violations of the forms in accordance with GOST 30242-97 weld include:
- undercuts (5011 and 5012; F);
- shrinkage grooves (5013);
- convexity of the excess butt (502) and angular (503) joints;
- excess proplava (504);
- irregular profile of the seam (505);
- naplav (506);
- linear (507) and angular (508) displacement of welded elements;
- incrustation (509);
- burn-through (510);
- not completely filled with cutting edges (511);
- extreme asymmetry of the fillet weld (512);
- non-uniform width of joint (513);
- rough surface (514);
- concavity of the root of the weld (515)
- and others
The offset between welded components with their parallel arrangement at different levels is called the linear displacement , and at the location of the edges of elements at an angle - angular displacement . Excessive asymmetry of the fillet weld size is a significant excess of one leg over the other.
Naplav - is an excess of the deposited weld metal, natekshy on the surface of the base metal. Nateq - a weld metal with no fusion of the joined surface and formed as a result of redistribution of the deposited weld metal by the force of gravity. Incrustations often occur during welding of fillet welds and butt welds in the horizontal position.
Burn-through - streaming metal weld pool, leading to the formation of through-hole in the seam. If the wrong profile joint angle between the surface of the base metal and the plane tangent to the surface of the weld is less than normal value.
All defects that are not included in groups 1-5 (GOST 30242-97), relate to other defects (600):
- local damage to the metal due to accidental ignition of the arc (601);
- spatter (602);
- scratches the surface (603) - surface damage due to the removal temporary welded aids;
- thinning of the metal (606)
- and others
welds and joints