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
What is Plain Concrete Footing? Plain Concrete Footing: Footings carrying relatively light loads are constructed with plain concrete. You have already seen a plain concrete

The following data is provided for belt transmission dynamometer as shown in figure, NA = 400 r.p.m., DA = 750 mm, DB = DC = DD = 250 mm, L = 800mm, Power = 8KW. Determine :- Th

Explain about structural design of combined footing. Structural Design of Combined Footing The rectangular and trapezoidal combined footings are designed assuming uniform so

type of furances and disadvantage advantage

Q.   Give the expression for inductance of a ? N ?    turn coil wound on a core having length I cross - sectional area A and magnetic permeability µ. Explain the significance of

Q. Safety from Corrosive Chemicals? Safety showers and eyewash stations shall be provided in areas where corrosive chemicals are stored and handled. They should be located so t

Q. Determine the size of grains using fineness test of sand? Fineness test :   Fineness test of sand specimen determines the size of grains and the distribution of grains of

In a 4-Bar process the following data is given :- Length of crank (AB) = 300 mm, Length of link AD = 600 mm, Length of links BC = CD = 360 mm, Angle BAD ie ∠BAD = 60o ,

Q. Explain about water De-Oiling process? The De-Oiling process consists of three major components: The Surge and Skim Tank which reduces PW oil content to 100 ppm I

Example of support reaction: A fixed crane of 1000Kg mass is to lift 2400Kg crates. It is held in place by pin at point A and a rocker at point B . the C . G . is located