Weld defects, Mechanical Engineering

Assignment Help:

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.


Related Discussions:- Weld defects

Newton s rings, how i make assigment for newton s ring

how i make assigment for newton s ring

Resulting structure of steel, Resulting structure of steel: Heat treat...

Resulting structure of steel: Heat treatments as mentioned below are given to thin steel strips for which TTT diagram is as shown in Figure 19. What will be the resulting stru

Scanning electron microscope, 1- Explain the rationale of using a small WD ...

1- Explain the rationale of using a small WD to improve resolution. 2- In a tungsten SEM , Why does a high accelerating voltage provide the potential for higher resolution?  Why

Determine the increase in pressure in vessel, Determine the increase in pre...

Determine the increase in pressure in vessel: A thin spherical vessel of diameter 750 mm & wall thickness 8 mm is filled through water at atmospheric pressure. Determine the i

Determine the resultant of force system, Q: Determine the resultant of forc...

Q: Determine the resultant of force system which is acting tangential to the circle of radius 1m as shown in the figure given below. Also find the direction of it and line of actio

Compute monitoring and control, Compute Monitoring and Control: These are t...

Compute Monitoring and Control: These are the direct application in which the computer is connected directly to the manufacturing process for the purpose of monitoring or contr

Huckel theory - quantum and spectroscopy, (1) Huckel Theory: Using Huckel t...

(1) Huckel Theory: Using Huckel theory, write a program that solves for the molecular orbitals and energy levels in a conjugated or aromatic hydrocarbon (i.e. ethylene, butadiene,

Clutch-free pedal play -factors in clutch design , Clutch-free Pedal Play :...

Clutch-free Pedal Play : To reduce effective clamping load on the carbon thrust bearing and wear thereof, sufficient clutch free pedal play must be provided in the clutch.

Determine the elongation of plate, Determine the elongation of plate: ...

Determine the elongation of plate: Q: A steel bar AB which is having uniform thickness 2 cm, tapers from 1.5 cm to 7.5 cm uniformly in a length of 50 cm. From 1 st principle

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd