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
ES 347 - Thermodynamics Project Assigned: 3/28/2013 Due: 4/25/2013 Problem specification 5 kg of air is contained in a piston-cylinder device, initially at a pressure of 2MPa and a

Find the coefficient of friction between ladder and floor: A ladder of 5m long rests on horizontal ground and leans against smooth vertical wall at an angle of 70° with the h

Find out extension: Q: A bar having length 25mm has varying cross section. It carries load of 14KN. Find out extension if cross section is given by (6 + x 2 /100) mm 2

Question: (a) (i) Describe the difference between intrinsic and extrinsic semiconductors. (ii)Is it possible for compound semiconductors to exhibit intrinsic behaviour? Desc

Q. What are Interconnecting pipe racks? Interconnecting pipe racks carry the main process inlet, export and transfer lines and utility distribution lines to and from process an

Shifting of Gears: To obtain different size combinations of gears, the gears slide on their shafts to mesh with different gears. The position of different gears, e.g. 1st, 2nd, 3r

the component of computer integrated manufacturing with the diagram


Question. In the system shown below, the force exerted by the free jet issuing from the sharp-edged circular nozzle and impinging on the small circular plate is just su±cient to k

Define the Gear Hobbing This is the most productive of all the gear production processes. However, it can only be used for producing spur gears and worn gears. It cannot be use