Laser welding is a high intensity laser beam radiation to the metal surface, after laser with metal effect, each other metal absorption laser is converted into heat energy to make metal melt cooling crystallization structure after welding.
Principle of laser welding machine has two kinds: the first kind, the heat conduction welding when the laser shining appearance in data, part of the laser is reflected, part absorbed by material and convert light energy into heat energy and heating melting, material surface depth of heat to heat conduction method for data transfer, will eventually two welding welding together.
Second, deep penetration laser when material in large power density laser beam shine into appearance, materials absorb light energy is converted into heat energy, melt materials are heated to boil, happen a lot of metal vapor, in the steam out of appearance under the counter productive force of the molten metal liquid, near to the pit, follow the laser continues to shine, pit more deeply wear, when laser to suspend the shine, pit surrounding liquid reflux, cooling condensation after two welding welding in -
Mechanism of the two kinds of welding properties and welding according to the practice of data need to choose, after adjusting the laser welding technology parameters to get different welding mechanism.
The difference of the two methods: stick to shut down the former pool appearance, while the latter molten pool is laser beam penetration into holes.
Conduction welding less disturbance on the system, because of the laser beam radiation has not penetrate the welding materials, so, in the process of conduction welding seam is not easy to be gas invasion;
And deep penetration, hole close to the hole.
Conduction and deep penetration welding method can convert each other, and at the same welding process by conduction method to the holes of change depends on the workpiece peak laser energy density and laser pulse duration.
Laser pulse energy density of time dependent function enough to make the time effect of laser welding in laser and data from a welding method to another method change, namely the weld in the process of effect of each other to form under the conduction method, first and then change to puncture method.
1, laser deep penetration welding the weld shape on high power for molten metal at the weld molten pool, because the data of instantaneous vaporization and form deep wear round concone cavity, followed by laser beam and the relative motion of the workpiece to close the holes around the metal melting, activities, constantly, condensation and constitute a succession of weld, the weld shape deep and narrow, with a larger penetration weld width ratio, the high power equipment, when welding the depth width ratio can reach 5: l, up to now.
Four kinds of welding method on 316 stainless steel and DUCOLW30 steel weld cross section shape comparison, according to conclusions are the following: 1)
Laser than TIG welding and electron beam welding and the primary strengths of plasma welding similar: narrow, the depth of penetration and weld, two parallel, small heat affected zone;
TIG and plasma welding paid less, and is widely used for many years, experience in many;
Laser welding and electron beam welding in high productivity advantages.
But local vacuum electron beam welding shall be in the vacuum chamber or.
Can also be in the air, but penetration ability inferior to the laser welding;
Laser welding and electron beam welding, weld and heat affected zone is small, so the deformation of the smallest.
2, the arrangement of the laser welding seam features when choosing high power laser beam welding, because of its high energy density, the welding workpieces through rapid thermal cycle of heating and cooling effect, makes the weld seam and heat affected zone is extremely narrow, the hardness is much higher than the parent metal.
As a result, the area of plastic is relatively low.
To drop stiffness of the joint area should adopt preheat before welding and corresponding technical measures such as tempering after welding.
Immediately after the tempering is a laser welding of non focus on low energy density beam is scanned for multi-channel welds then drop weld hardness of new technology.
Laser welding of metal and the arrangement is by the chemical composition and hardness of heat affected zone and cooling velocity resolution.
In laser welding, the welding technology usually don't need a filler metal.
In this case, the arrangement of the weld and the primary by steel chemical composition and hardness of the laser shining to resolution.
Laser welding with filler wire because can pick any alloy wire as good weld transition alloy, so can ensure the parent metal on both sides of the connection has a good function.
To high melting point, high heat conductivity, physical properties of different species or the same metal material welding.
Can be free from contamination and less impurity, weld.
Laser welding heating speed, welding molten pool cooling rapidly, and the general practice of welding on the metallographic arrangement is a big difference.
Laser welding machine