Weld defects, Mechanical Engineering

WELD DEFECTS

The common defects encountered in submerged arc welding are:

  • a. Slag inclusion
  • b. Porosity
  • c. Cracking of welds.

 

a). Slag Inclusion: Slag inclusion is the result of incomplete dislodging of each layer during multiphase welding.  Using Proper cleaning of each  pass, the defect can be avoided. Improper  wire positioning creates under cuts resulting in slag inclusion in those areas.

b). Porosity: Porosity in submerged arc welding occurs mainly due to the presence of contaminants in the metal surface or electrode and due to moisture pick up by the flux. In addition, the gases generated during welding may get entrapped in weld due to improper selection of process parameters such as excessive current, too high welding speed or excessive height of flux layer.

c). Cracking: The main factor in promoting cracking in the weldment is the chemical composition of the steel itself. If the steel is hardemable, cracking  can be avoided by proper selection of preheat and by controlling the hydrogen level during welding. Cracking may also occur due to susceptibility of the material to hot shortness.

This defect is mainly associated with the sulphur content in the weld and can be controlled by the adjustment of manganese content in the flux. The other major cause of cracking could be due to the external restraints forced on to the joint during cooling. In general, the weld metal cracking can be avoided by proper selection of current, voltage and travel speed to yield a weld deposit with a bead formation factor, that is bead width to depth ratio around 3:2.

Posted Date: 9/14/2012 7:20:46 AM | Location : United States







Related Discussions:- Weld defects, Assignment Help, Ask Question on Weld defects, Get Answer, Expert's Help, Weld defects Discussions

Write discussion on Weld defects
Your posts are moderated
Related Questions
The first laboratory report, covering the two-part exercise involving tension testing and stress concentrations is due in lab two weeks after the conclusion of fatigue testing.

how will you detect the depth of sea and application?

Flux Cored Arc Welding (FCAW) This is a variation of GMAW where solid wire is replaced by flux cored wire. The equipments and accessories are the same. Generally, flux cored wi

Illustrate Newton's law of viscosity. Explain the importance of viscosity in fluid motion. Describe the effects of temperature on viscosity of water and that of air? Discuss hyd

At a sudden enlargement of a water main from 240 mm to 480 mm diameter, the hydraulic gradient rises by 10 mm. Estimate the rate of flow.

what is helix angle and how to determine it?

REACTIO N TURBINE: The turbine in which the steam expands while passing over the moving blades as well as while passing over the fixed blades and the pressure of steam dec

compressor’s volumetric efficiency can also depend on the compressor’s ratio.

Sliding and Rolling Consider the following example. A cylinder of mass  M  and radius  R  is held at rest on a plane inclined at an angle to    to the horizontal. When the cyl

Discover modulus of elasticity of the composite: A composite of glass fibres and epoxy contain all fibres laid along the length and is needed to carry a stress of 1200 MPa. Th