Welding involves joining two metal parts using heat to melt them together. Weld overlay involves adding to the surface of a metal component to recover lost dimensions [ Additive remanufacturing] or changing the chemistry of the metal surface [ corrosion resistance]. Using the laser as the heat source, hot and cold wire feed welding are two types of laser welding processes that can be used to supply metal material to the weld puddle. For laser welding it is primarily for improved weld root enforcement, and for laser weld overlay it is for cladding the part. Though like gas tungsten arc welding (GTAW), hot and cold wire feed laser welding features quicker, cleaner welds, lower dilution welds which lower costs and improves performance for clients.
Below we explain these processes in depth and compare their advantages and disadvantages.
What Is Hot and Cold Wire Feed Welding?
Hot and cold wire feed welding are distinct processes that yield near-perfect fillet welds and minimal distortions.
What Is Hot Wire Laser Welding?
Hot wire laser welding uses a custom welding power supply resistively heated filler wire, and the laser is the melting heat source. This combination promotes accurate weld location placement. Electrical resistance heats the filler material near to melting, forming the hot wire, but a controlled power supply prevents plasma or arcing. The laser provides the final heat source to melt and weld the filler to the metals.
Hot wire laser welding is a lower-heat input process that produces yields lower dilutions, low distortion, and improved quality.
What Is Cold Wire Laser Welding?
Unlike hot wire laser welding, cold wire laser welding only relies on the laser for the heat source. The wire is fed into a weld puddle generated by the laser.
Hot vs. Cold Wire Laser Welding
The main difference between hot and cold wire laser welding involves thermal dynamics. Less energy is required to melt a hot metal than a cold metal. The energy required to melt a certain mass of metal depends on its heat capacity and heat of fusion.
Three-quarters of the total energy required to heat a metal alloy from room temperature to molten temperature [Heat capacity]. The other 25% is required to melt the alloy [heat of fusion]. For this reason, hot wire laser welding has more advantageous than cold wire laser welding, but with the disadvantage of added process complexity and equipment cost.
Advantages of hot over cold wire
Deposition rate five times higher
Reduces dilution, distortion, and residual stress
Reduces machining and non-destructive examination
Disadvantages of hot over cold
More expensive capital equipment
Limited selection of compatible wires
Laser Feed Welding Applications
Laser feed welding and cladding are can be used is just about every application in which common welding and weld over lay techniques are used today.
Advanced Cold Wire Welding and Hot Wire Welding at Titanova
If you need a cutting-edge welding solution, Titanova is your ideal partner. We are dedicated to developing new laser technologies for the welding industry, such as cold and hot wire laser welding and cladding. We also provide non-cutting laser processes such as laser heat treating and laser hard facing.
Titanova has served many critical industries, from aerospace , steel manufacturing, agriculture , mining, energy generation and many others. Contact us today to learn how we can serve you with our advanced welding services.
Posted by John Haake on | Comments Off on Hardfacing Methods
Hardfacing delivers a wear-resistant and hard coating of material on the surface of a worn component or a new component that will be subject to wear. There are various methods that can be used to apply the hardfacing layer. Common methods include:
Diode Laser Hardfacing
The different hardfacing techniques provide different results to suit a range of applications. This blog will describe the various hardfacing methods to help you determine the ideal method for your application or industry.
Laser WC Hardfacing Mixing Plow
Types of Hardfacing Methods
There are various methods for hardfacing, which include:
Diode Laser Hardfacing
Diode laser hardfacing can increase lifespan and reduce wear of material handling components. The coating is extremely wear-resistant, relying on a laser to weld a thin metal layer embedded with super hard particles. Diode laser hardfacing produces a thin, smooth, and uniform coating. It provides a hard particle density of up to 75% and prevents burning carbides with low heat application.
Submerged Arc Welding (SAW)
SAW relies on flux to unite slag and protective gases into the weld pool. When welding, an arc forms between the flux and the workpiece surface through a continuously fed wire electrode. SAW provides excellent deposition rates, deep penetrating welds, and versatility to perform indoors and outdoors. The leftover flux can also be recycled using a flux recovery system.
Flux Cored Arc Welding (FCAW)
FCAW uses a continuously fed tubular flux-filled electrode and requires constant voltage. It is not ideal for all metals but provides excellent penetration and a high deposition rate. FCAW is suitable for any welding position and allows for manual, automatic, and semi-automatic operations. It is ideal for construction applications due to its mobility and speed.
Shielded Metal Arc Welding (SMAW)
This manual arc welding process relies on a covered flux consumable metal electrode that shields the weld pool. It forms an arc between the electrode and the metal substrate using an electric current. When laying the weld, the flux coating disintegrates and creates a layer of slag and shielding gas to protect the weld while cooling. SMAW has lower deposition rates than other welding techniques but works with a range of metals and alloys. It also allows for diesel or gas power, making it highly portable and suitable for remote regions.
Gas Metal Arc Welding (GMAW)
GMAW or MIG welding relies on a welding gun with a consumable wire electrode and a shielding gas. The process is automatic or semi-automatic and typically uses a constant voltage. While it is unusable for overhead and vertical welds, it requires little cleaning post-weld thanks to its low slag generation and provides high deposition rates with low consumable costs.
Gas Tungsten Arc Welding (GTAW)
GTAW or TIG welding creates an arc between the workpiece and a non-consumable electrode, and an inert gas barrier is formed to protect the welding pool. It has lower deposition rates than other methods but leaves a clean finish without producing slag. GTAW also offers a high range of flexibility, allowing welding to be manually or automatically performed in any position and with a wide range of metals.
Thermal spraying is a hardcoating method that sprays heated or melted materials onto a surface. It relies on chemical or electrical heating to spread a coating up to several millimeters thick over a large area with a higher deposition rate than other methods. Thermal spraying works with various material surfaces and does not heat the surface significantly, making it suitable for coating flammable materials.
Oxygen-acetylene hardfacing is a relatively simple method for those familiar with welding. It is not ideal for coating large components, but it provides low weld deposit dilution and provides enhanced control of the deposit shape. Oxygen-acetylene also delivers lower thermal shock with a slower heating and cooling process.
Metal Compatibility With Hardfacing
Various metals are compatible with hardfacing. The primary requirement for a prospective material to be compatible with hardfacing is a carbon content lower than 1%. Low-alloy steels and carbon steels are typically compatible, but high-carbon alloys may require a special buffer layer.
The following metals offer compatibility with hardfacing:
Cast Iron and Steel
Partner With Titanova for Your Laser Hardfacing Needs
Industrial hardfacing can be applied to various materials using diode lasers, thermal spray, and several welding methods. Each method provides unique benefits and can reliably apply a hardfacing coating on a range of metals. Learn more about Titanova’s laser hardfacing capabilities and contact us to speak with a representative today.