- Carbon and common alloy steels In general, carbon steels can be laser welded with good results, but the quality of the weld depends on the impurity content.
Sulfur and phosphorus in the material are sensitive to weld cracking and are not suitable for laser welding if the sulfur and phosphorus content is high. Medium and high carbon steels and common alloy steels can be laser welded well, but require preheating and post-weld treatment to eliminate stress and avoid crack formation. - Laser welding of stainless steel In general, laser welding of stainless steel is easier than conventional welding to obtain quality joints.
The low thermal conductivity of stainless steel is easier to obtain deep fusion narrow welds. Stainless steel is mainly divided into ferritic stainless steel (joint embrittlement), austenitic stainless steel (hot cracking), martensitic stainless steel (poor weldability), duplex stainless steel (weld-affected zone is easily embrittled). - Mold steel
S136, SKD-11, NAK80, 8407, 718, 738, H13, P20, W302, 2344 and so on. - Laser welding of aluminum alloy
Laser welding of aluminum alloys is difficult due to the high reflectivity and high thermal conductivity of the surface. For laser welding of highly reflective materials, the energy threshold is more obvious.
The welding performance is different for different grades of aluminum alloys.
Aluminum’s strong oxidation ability: Aluminum in the air and welding is very easy to oxidize, generated by the high melting point of alumina, very stable, not easy to remove the oxide film of the specific gravity, not easy to float out of the surface, easy to generate slag, not fused, not welded through and other deficiencies. Aluminum surface oxide film and adsorption of a large amount of water, easy to make the weld porosity. Therefore, the cleanliness of the workpiece has high requirements.
Larger thermal conductivity and specific heat capacity. Should try to use energy concentration, high power energy, and sometimes can be used to preheat and other process measures. The general requirements of the laser power is relatively large.
Larger coefficient of linear expansion, aluminum solidification volume shrinkage is larger, the deformation and stress of the weldment is larger, aluminum welding molten pool solidification is prone to produce shrinkage, shrinkage, thermal cracks and higher internal stress.
Aluminum to light, heat reflection ability is strong, solid, liquid transmutation state, there is no obvious color change, welding operation is difficult to judge. High-temperature aluminum strength is very low, supporting the molten pool is difficult, easy to weld through.
Easy to form pores: aluminum and aluminum alloy in the liquid state can dissolve a large amount of hydrogen, solid state almost no hydrogen dissolved. In the process of solidification and rapid cooling of the weld pool, hydrogen is too late to overflow, and it is very easy to form hydrogen pores.
There are high requirements for cleanliness of the workpiece, including dryness of the workpiece and the surrounding environment.
The alloying elements are easy to evaporate and burn, so that the performance of the weld is degraded. - Welding of copper alloys
Similar to the welding of aluminum alloys, but the reflective properties of mirrored copper are stronger. The most commonly used grades in the industry are T1, T2 and T3, which have a purplish-red appearance, so they are also known as purple copper. Prone to welding defects: unfused and unwelded (high energy density of the laser beam), welding deformation, thermal cracking (in the crystallization process, due to the low melting point of the co-crystal distribution in the dendrite or grain boundaries, so that the copper and copper alloy with a significant thermal brittleness, coupled with the role of welding stress, is highly susceptible to thermal cracking), porosity (copper weld in the porosity of hydrogen porosity is the main). - Laser welding between different steels
Laser welding very high cooling speed and very small heat-affected zone, for many different metals after welding melt with different structure of the material to create a favorable condition for compatibility. The following metals can be successfully laser deep fusion welding: stainless steel ~ mild steel, 416 stainless steel ~ 310 stainless steel, 347 stainless steel ~ HASTALLY nickel alloy, nickel electrode ~ cold forged steel, different nickel content of the bimetallic strip. - Titanium, nickel, tin, copper, aluminum, chromium, niobium, gold, silver and other metals and their alloys, and steel, Corvair alloys and other alloys of the same material between the welding. Non-ferrous metals are relatively difficult to weld, its purple copper alloy, silver alloy is the most difficult to weld.
- Apply to copper – nickel, nickel – titanium, copper – titanium, titanium – molybdenum, brass – copper, mild steel – copper and other dissimilar metals between the welding.
Because of this we can also find its shortcomings in the process:
① Welding position must be very accurate, must be within the focusing range of the laser beam.
② high reflectivity and high thermal conductivity of materials such as aluminum, copper and its alloys, etc., the weldability will be changed by the laser
③ The energy conversion efficiency is too low, usually less than 10 percent.
Of course, it also has many advantages:
① Laser welding is not limited by conditions. At room temperature, vacuum or other environments can work normally.
② laser can weld refractory, exotic materials.
The laser can weld refractory and exotic materials. ③ It can accurately position the material.
④Welding material will not be deformed
Although it has shortcomings, but it also has the advantages that can not be ignored, which is also the reason why it is more and more favored by the majority of businessmen.