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
Describe with suitable diagram the governing of impulse turbines. What are design aspects of Pelton wheel turbine and also explain all the terms. Derive mathematical formula

show that work is a path function and not a point funtion ?

Determine the maximum value of the coefficient of friction: A force of 200 N inclined at 60 o to the horizontal is applied to the block A weighing 400 N. find out whether blo

Stress-strain carves for ductile materials: A material is said to be ductile in nature, if it elongates before fracture. One this type of material is mild steel. Shape of stre

Find the maximum shear stress - stepped circular bar: A stepped circular bar ABC 4 m long fixed at one of the end 'A' is subjected to a torque of 10 kN-m. If the portion AB is

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4 Explain the Methodol


Illustrate various kinds of control systems. Illustrate several block diagram reduction rules with examples. Determine C/R by using block diagram reduction method.

Loa d Diagram and BM D fro m the Given SF D: Q: Shear force diagram of simply supported beam is given in the figure below.  Calculate the support reactions of beam and

a) Define various types of chips and factors responsible for their formation with diagram b) Describe cutting ratio, shear plane and shear angle. c) Sketch Merchant circle di