Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature metal-joining techniques such as brazing and soldering, which do not melt the base metal.
In addition to melting the base metal, a filler material is typically added to the joint to form a pool of molten material (the weld pool) that cools to form a joint that, based on weld configuration (butt, full penetration, fillet, etc.), can be stronger than the base material (parent metal). Pressure may also be used in conjunction with heat or by itself to produce a weld. Welding also requires a form of shield to protect the filler metals or melted metals from being contaminated or oxidized.
Many different energy sources can be used for welding, including a gas flame (chemical), an electric arc (electrical), a laser, an electron beam, friction, and ultrasound. While often an industrial process, welding may be performed in many different environments, including in open air, under water, and in outer space. Welding is a hazardous undertaking and precautions are required to avoid burns, electric shock, vision damage, inhalation of poisonous gases and fumes, and exposure to intense ultraviolet radiation.
Until the end of the 19th century, the only welding process was forge welding, which blacksmiths had used for millennia to join iron and steel by heating and hammering. Arc welding and oxy-fuel welding were among the first processes to develop late in the century, and electric resistance welding followed soon after. Welding technology advanced quickly during the early 20th century as world wars drove the demand for reliable and inexpensive joining methods. Following the wars, several modern welding techniques were developed, including manual methods like shielded metal arc welding, now one of the most popular welding methods, as well as semi-automatic and automatic processes such as gas metal arc welding, submerged arc welding, flux-cored arc welding and electroslag welding. Developments continued with the invention of laser beam welding, electron beam welding, magnetic pulse welding, and friction stir welding in the latter half of the century. Today, as the science continues to advance, robot welding is commonplace in industrial settings, and researchers continue to develop new welding methods and gain greater understanding of weld quality.
I put my tea in the microwave this morning then went to sit on the sofa. I heard some crackling noises, similar to the sound that metal makes when in a microwave.
I ran over, and hit stop then opened the microwave. The microwave tray was over to one side. I took the mug off but the tray...
I am thinking about taking courses about welding later this year. I want to prepare in advance. Do you know any accesible resources about welding? Especially things which explain the fundamentals. I look for solid hard information which will help me later. I want to understand the advantages and...
Hello,
I know AC is used for welding of Aluminum or materials that have oxide layer on the surface
Books also tell me that the oxide layer is cleaned by AC
However, what is the exact mechanism of this cleaning action? Besides, where does the oxide gone? Vaporized? Dissolved?
Thanks
Just a quick question from a potential mech. engineering student. I'm probably going to start soon on my formal MechE classes soon but I know that to be a good engineer, you need to do more than get good grades. I've asked a lot of working MechEs about what you need to know, specifically if...
Hi all.
As part of a Uni project I need to calculate the torque required to rotate one pipe relative to another stationary pipe so the two ends of the pipes are in contact with each other and therefore the rotation and the axial force of the rotation pipe causes friction and melt.
I know at...
Hello,
I arrived here following links to "heat exchange".
I've got a small (200amp) tig welder and would like to move up to a water cooled torch. I'm building my own cooler in my workshop. I'm challenging myself to fit a cooler into the smallest package possible, the only limits being my...
by cold welding i mean diffusion bonding, explosive welding, cold pressure welding etc.
in what situations would one use these techniques and what are the benefits of employing them over traditional methods such as arc welding?
Hi,
I want to know the peak temperature attained and temperature distribution with time in a frictional welding process ( ultrasonic consolidation between an Al substrate and Al strip). The problem with normal thermocouples is that by the time it shows the temperature , the temperature has...
Homework Statement
Given, the density, specific heat per unit volume, latent heat of fusion, melting point and thermal conductivity - calculate the energy needed to melt a cubic mm of carbon steel, starting at 20 celcius.
Hence find the minimum power needed to generate a bead on a plate...
This is kinda hard to explain without a drawing but I'll try. Imagine an L-shaped structure with a weld going down the vertical part connecting the L to a vertical pipe on the left side of the L. The curvature of the pipe is insignificant. Then on the L's right end is a vertical downward load. I...
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...
I have time on my hands these days so I bought a Mig/flux welder. I have no idea what I’ll do with it but I always wanted one. The machine allows welding with wire that has a flux core or with a gas “shield. Presumably the gas or flux prevents oxidation of the metal when heated.
The...
Dear . . . Physics Forum
May I Ask Some Help ?
I need a website that makes me learn more about :
1. Arc Welding Machines .
2. Arc Welding Technology .
3. Welding Rodes Specifications .
4. The Calculations That We Need For How Deciding The Welding Rode Diameter Depending On The Working...
May I Ask This Question ... Please ...
There is many sizes of Arc Welding Wires ... ( 1.5 ) , ( 2 ) , ( 2.5 ) ... etc.
On what depend exactly the use of each size ... ?
There is also on the Welding Machines a Volatge Controller ... for increasing or decreasing the welding voltage ...
I do not know how to do the second part of this question. I never learned this.
A laser used to weld detached retinas puts out pulses of 640 nm light, 25 ms long, which average 0.50 W output during a pulse.
i) how much energy can be deposited pre pulse?
ii) If the energy of a light...
If I'm understanding it correctly, my book says that frictional forces are the result of cold welds - that when two surfaces are in contact with one another, the highest points on the surfaces on an atomic scale weld together to form a single object, and these welds are what resists movement...