Calculate Welding Heat Input per Point

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    Heat Input Welding
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Discussion Overview

The discussion revolves around calculating the welding heat input per point during a welding process, focusing on the relationship between welding parameters such as current, voltage, speed, and their effects on heat input and residual stresses in the weld. It includes theoretical considerations and practical implications in welding applications.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant calculates the heat energy generated during welding as 2.2 KJ/sec based on current and voltage, seeking to determine heat input at each point along the weld.
  • Another participant suggests that the heat input per unit length can be calculated by dividing the power generated by the welding speed, assuming no losses.
  • Concerns are raised about the impact of increased welding speed on heat input and residual stresses, with one participant suggesting that faster welding could lead to less residual stress but may compromise weld penetration.
  • Another participant counters that while faster welding may reduce residual stresses, it could also sacrifice weld penetration, emphasizing the need for balance in welding parameters.
  • A more technical perspective is introduced regarding the relationship between heat input, residual stress gradients, and the effects of arc power on the yielded zone, suggesting that post-weld heat treatment may be necessary.
  • Discussion includes the advantages of power beam welding processes, which may produce lower net heat input and smaller heat-affected zones compared to electric arc welding, questioning the effectiveness of simply increasing welding speed.
  • A participant inquires about the appropriate method for inputting heat sources in welding simulations using ANSYS, asking for clarification on parameters like efficiency, voltage, current, and welding speed.

Areas of Agreement / Disagreement

Participants express differing views on the effects of welding speed on heat input and residual stresses, indicating that multiple competing perspectives exist without a clear consensus on the optimal approach.

Contextual Notes

Participants note various assumptions, such as the neglect of losses in energy calculations and the complexity of balancing welding speed with penetration and residual stresses. The discussion reflects the nuanced nature of welding parameters and their interdependencies.

chandran
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In a welding process,i am welding two plates. The welding current is 110A and welding voltage is 20V. Suppose 100% of this electric energy is
converted to heat then the heat energy generated is 110x20. i.e., 2.2KJ/sec.
Suppose the length of the plate is 2 metres, How can i calculate what is the heat input into the welded joint at each point? I have one more data
that welding speed is 1metre/minute.
 
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(assuming no losses) power generated / welding speed = heat input per unit length
 
if the welder weld faster then heat will be less thereby producing a good
less,residual stress weld?
 
chandran said:
if the welder weld faster then heat will be less thereby producing a good
less,residual stress weld?
Perhaps. Any weld is going to create stresses. The increased speed would have to be balanced by the fact that a certain percentage of the weld penetration would be sacrificed. Most welds are stress relieved after the process.
 
Yeah, if you require the weld to penetrate (well, you usually do) I think you can't really gain much residual stress wise by decreasing heat input (material properties are a different matter of course). Typically heat input affects the residual stress gradient at line of fusion towards the base material, where there is a square root dependency between the yielded zone and arc power, which again has a linear relationship with the extension of the residual stress field - but this leaves the weld metal residual stresses still as is, higher arc powers widen the volume under residual stresses. Would go with post-weld heat treatment.
 
Power beam welding processes (e-beam, laser welding) tend to be better in applications where residual stress is a concern. The power density is much higher, although the net heat input is often lower than electric arc welding techniques. As a result, the heat affected zone tends to be a lot smaller. (Pretty much what Perennial said...). I don't think a simple increase of welding speed is going to solve any problems.
 
Hello, How to input heat source in welding simulation ( ANSYS ).By heat flux or heat genaration or heat flow etc...?.How to calculate if effic=60%,V=16, I=80,weld speed=1 m/min.
 
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