What Materials Can the Laser Welding Machine Weld?
Nov. 12, 2024
Laser welding is one of the most advanced welding technologies in the world today. It utilizes high-energy laser pulses to locally heat a material in a small area. The laser radiation energy is then diffused into the material through heat conduction, causing the material to melt and form a specific molten pool. This innovative welding method is primarily used for joining thin-walled materials and precision components. It is capable of spot welding, stitch welding, sealed welding, and more, offering advantages such as a high aspect ratio, narrow weld width, minimal heat-affected zone, fast welding speed, and aesthetically pleasing results. Additionally, it requires little to no post-weld processing, features a small focus spot, and offers high positioning accuracy, making it ideal for automation.
As for the materials that laser welding machines can weld, they are versatile and can work with a wide range of materials, including:
- Metals: Steel, stainless steel, aluminum, titanium, copper, and precious metals like gold and silver.
- Non-metals: Certain plastics and ceramics, when specifically designed for laser welding.
1. Die Steel
Laser welding machines are highly effective for welding various types of die steel, such as S136, SKD-11, NAK80, 8407, 718, 738, H13, P20, W302, 2344, and others, delivering excellent results.
2. Carbon Steel
Laser welding of carbon steel yields good results, although the welding quality is influenced by the level of impurities. To achieve high-quality welds, preheating is necessary when the carbon content exceeds 0.25%. As carbon content increases, the risk of weld cracks and notches also rises. Both medium and high-carbon steels, as well as ordinary alloy steels, can be successfully welded with laser, but preheating and post-welding treatments are essential to relieve stress and prevent cracking.
3. Alloy Steel
Laser welding of low-alloy high-strength steels can achieve joints with mechanical properties comparable to the base material, provided the appropriate welding parameters are selected.
4. Stainless Steel
Laser welding of stainless steel offers several advantages due to the small heat-affected zone and reduced welding speed, which help mitigate overheating and reduce the impact of stainless steel's large linear expansion coefficient. This results in welds without defects such as pores and inclusions. Compared to carbon steel, stainless steel is easier to weld with deep penetration narrow welds due to its low thermal conductivity, high energy absorption rate, and melting efficiency. Thin plates can be welded with a low-power laser welding machine, achieving well-formed joints with smooth, aesthetically pleasing seams.
5. Copper and Copper Alloys
Welding copper and copper alloys presents challenges such as infusion, incomplete penetration, and the risk of large deformation after welding, especially when the workpiece is thin or lacks structural rigidity. To overcome these issues, a concentrated high-power heat source is necessary, along with preheating measures. When welding copper alloys, the welding joint may experience significant stress due to rigid constraints, and thermal cracking is a common concern. Porosity is also a typical defect when welding copper and copper alloys.
6. Aluminum and Aluminum Alloys
Aluminum and its alloys are highly reflective materials, which makes welding more difficult. As the temperature rises during welding, the solubility of hydrogen in aluminum increases sharply, leading to the formation of hydrogen-induced defects, such as pores. Deep penetration welding can result in cavities at the root and poor weld bead formation. This makes welding aluminum and its alloys particularly challenging without proper process control.
The characteristics of metal materials significantly influence the welding process. Below are the key considerations for metal laser welding:
1. Cooling Rate: Metal materials typically cool quickly, a factor influenced by the carbon content in the metal. This rapid cooling can affect the material's embrittlement, leading to the formation of microcracks and weakening the fatigue strength of the metal.
2. Volatile Alloy Elements: During welding, highly volatile alloy elements in the metal can evaporate from the molten pool. This can result in the formation of pores and may cause undercuts, impacting the weld's integrity.
3. Carbon Steel Welding: For carbon steel materials, the carbon content should be kept below 2%. When the carbon content exceeds 3%, laser welding becomes more challenging, with an increased risk of cold cracks, as well as a higher tendency for brittle fractures. It is crucial to account for weld shrinkage in the joint design to reduce residual stress and prevent cracking in the heat-affected zone.
4. Welding with Different Carbon Content: For metals with more than 3% carbon content, and those with less than 3%, employing a "paranoid" weld form can help minimize martensite transformation. This approach reduces stress, minimizes cracks, and slows the quenching rate, improving the overall welding quality.
5. Pulse vs. Continuous Welding: Whether using pulsed laser welding or continuous laser welding, pulse laser welding is particularly beneficial as it reduces heat input. This results in a decrease in thermal cracks and minimizes workpiece deformation.
