In the modern industrial manufacturing furnaces, laser welding and arc welding are like two sharp tools with distinct edges, jointly supporting the huge demand for metal connections. From precise and tiny medical devices to grand structures like ships and Bridges, although their application fields sometimes overlap, they also form distinct distinctions in core characteristics. A thorough understanding of the essential differences between these two major technologies is the key cornerstone for achieving precise selection and maximizing efficiency in engineering practice.
I. Sources of Energy: From Light quanta to Ionizing Arcs
Laser welding: Laser welding is an efficient and precise welding method that uses a laser beam with high energy density as the heat source. Laser welding is one of the important applications of laser material processing technology. Laser welding can be achieved by using continuous or pulsed laser beams. The principles of laser welding can be divided into heat conduction welding and laser deep penetration welding.
The principle of heat conduction type laser welding is as follows: The laser radiation heats the surface to be processed, and the surface heat diffuses into the interior through heat conduction. By controlling the laser parameters such as the width, energy, peak power and repetition frequency of the laser pulse, the workpiece is melted to form a specific molten pool.
(1) Power density Power density is one of the most crucial parameters in laser processing. By adopting a relatively high power density, the surface layer can be heated to the boiling point within a microsecond time range, generating a large amount of vaporization. Therefore, high power density is beneficial for material removal processing, such as drilling, cutting and engraving. For lower power density, it takes several milliseconds for the surface layer temperature to reach the boiling point. Before the surface layer vaporizes, the bottom layer reaches the melting point, which is conducive to forming a good fusion weld
(2) Laser pulse waveform. The waveform of laser pulses is an important issue in laser welding, especially for thin sheet welding. When a high-intensity laser beam is directed at the surface of a material, 60 to 98% of the laser energy on the metal surface will be reflected and lost, and the reflectivity varies with the surface temperature. During the period of a laser pulse, the reflectivity of metals varies greatly.
(3) Laser pulse width. Pulse width is one of the important parameters in pulsed laser welding. It is not only a crucial parameter that distinguishes material removal from material melting, but also a key parameter that determines the cost and volume of processing equipment.
(4) Welding speed. The speed of welding affects the amount of heat input per unit time. If the welding speed is too slow, the heat input will be too large, causing the workpiece to burn through. If the welding speed is too fast, the heat input will be too small, resulting in the workpiece not being penetrated.
Arc welding: Its energy comes from the arc formed by the continuous discharge between the electrode (electrode or wire) and the workpiece. The high temperature generated by the electric arc (usually above 5000°C) causes the electrode and the base metal to melt simultaneously to form a molten pool. Depending on the type of electrode and the protection method, it is further classified into multiple approaches:
Gas metal arc welding (MIG/MAG) : Continuously feed the welding wire as the electrode, and simultaneously spray inert or active shielding gas (argon, CO₂, or their mixtures).
Tungsten inert gas welding (TIG) : It uses a refractory tungsten electrode and is protected by inert gas (mainly argon). Filler wire can be added or not, and the base material is melted by the heat of the arc.
Shielded metal arc welding (SMAW) : The coated electrode melts under the heat of the electric arc, and the coating generates protective gas and slag to cover the molten pool.
Submerged arc welding (SAW) : The welding wire and granular flux are simultaneously fed into the arc zone. The arc burns beneath the flux layer, and the flux melts to form slag that covers the molten pool.
Ii. In-depth Analysis of Core Performance Dimensions
Laser welding: Significant advantages. Energy is highly concentrated, heat input is extremely low, and the heat-affected zone is very narrow. This significantly reduces welding deformation and residual stress, especially suitable for thin plates, precision parts and assembled components, effectively avoiding the subsequent cumbersome correction processes.
Arc welding: The heat input is relatively high and widely distributed, and the heat-affected zone is significantly wider. Deformation and residual stress problems are more prominent, especially in thin plate welding, where particularly cautious tooling design and welding sequence planning are required.
Welding speed and efficiency
Laser welding: Significant advantages. It has an extremely high energy density and a welding speed far exceeding that of most arc welding methods. Its advantages in high-speed automated production lines are irreplaceable.
Arc welding: The speed is relatively slow. Although submerged arc welding or high-speed MIG welding can achieve relatively high speeds, they are usually still lower than laser welding. Its efficiency is limited by the physical properties of the arc and the droplet transition process.
Penetration capacity and weld formation:
Laser welding: Advantages (especially deep penetration welding). The keyhole effect makes it good at achieving welds with a large depth-to-width ratio, and it can penetrate thick plates in a single pass. Weld seams are usually narrow and deep, with a smooth and beautiful surface.
Arc welding: Its penetration capacity is relatively limited, and the depth-to-width ratio is small. Welding thick plates usually requires beveling for multi-layer and multi-pass welding. The width of the weld seam is usually larger than that of laser welding, and the formation depends on specific process parameters and the welder's skills.
Iii. Material Adaptability and Thickness Range:
Laser welding
Advantageous materials: Common metals such as carbon steel, stainless steel, aluminum alloy, and titanium alloy are all applicable. For high-reflectivity materials such as copper and gold, special wavelengths (green light, blue light) or higher power are required to overcome reflection.
Thickness range: Proficient in thin plates and medium plates. High-power lasers (such as 10,000-watt fiber lasers) can also weld thicker materials (> 10mm), but the equipment cost has soared. Dissimilar metal welding (such as steel-aluminum) has great potential, but it requires precise control.
Arc welding
Advantages: It is applicable to an extremely wide range of materials, almost covering all weldable metals (steel, stainless steel, aluminum, copper, nickel-based alloys, cast iron, etc.). There are no special difficulties for highly reflective materials.
Thickness range: Extremely wide adaptability. It can handle everything from ultra-thin foils (requiring special technologies such as micro-beam TIG/Plasma) to giant structures hundreds of millimeters thick (such as submerged arc welding for shipbuilding and electroslag welding of thick plates), and is the main force in welding thick and large parts.
Laser welding, with its characteristics of high speed, low heat input, high precision and large aspect ratio, has stood out in the fields of precision manufacturing and efficient automation. Arc welding, with its advantages of wide material adaptability, strong thick plate capacity, low equipment cost and flexible operation, has a deep foundation in heavy industry and on-site construction. Both play to their strengths in the grand blueprint of industrial manufacturing and jointly drive the continuous expansion of the boundaries of connection technologies. The wisdom of an engineer lies in perceiving the core demands of specific application scenarios, and finding the most suitable balance point in the triangle of cost, efficiency and quality, making the connection of metals both firm and reliable, as well as efficient and economical.