Cast iron is widely used in various industries due to its unique properties. However, the challenges of repairing these components can be daunting because of the welding process. Titanova, a leader in laser cladding, has developed a proprietary technique that enables the repair of the biggest castings.
This article will explore the benefits of cast iron, the challenges involved in repairing it, and how Titanova’s laser cladding technique addresses these issues.
Cast Iron: A Versatile Material
Cast iron is an iron-carbon alloy with a high carbon content of over 2% and silicon between 1-3%. This chemistry allows for lower melting points, which is a main benefit to the industry.
Cast iron has many classes and subclasses, each with unique properties and applications. The following are the several types of cast iron:
Grey cast iron: used in gearbox cases, engine cylinder blocks, flywheels, and machine-tool bases
White cast iron: used in anti-erosion piping and bearing surfaces
Malleable iron: used in axle-bearing retainers, track wheels, and automotive crankshafts
Ductile or nodular iron: used in gears, camshafts, and crankshafts
Ni-hard Type 2: used in high-strength applications
Ni-resist Type: used for resistance to heat and corrosion
Challenges of Repairing Cast Iron
Here are some of the main obstacles to repairing cast iron components:
Welding Difficulties
Cast iron contains a high amount of carbon, typically between 2% and 4%. This carbon content causes the material to become brittle and prone to cracking when exposed to high heat during welding. Welding also causes the carbon to migrate to the weld pool, leading to porosity and weakening the weld joint.
Microscopic Impurities and Inclusions
Cast iron is not a pore-free material; it contains microscopic impurities and inclusions that make it challenging to repair. These inclusions come in various shapes — from flakes to spherical nodules — and can cause stress concentration, leading to cracks and fractures.
Saturation of Lubricants and Other Surface Substances
Cast iron components used in industrial applications are often exposed to various substances. This includes lubricants, greases, and water that can saturate the surface and create a barrier to adhesion during the repair process. This makes it difficult to achieve proper bonding and leads to failure in the repaired area.
Costly and Time-Consuming Preheat Requirements
Repairing cast iron often requires preheating the component to slow down the cooling rate of the weld and the surrounding area. However, preheating large cast iron components can be time-consuming and expensive, often requiring temperatures between 500-1200 °F. Preheating must also be done uniformly, or it can cause the part to crack, making the repair process even more challenging.
Titanova has years of experience and expertise in laser cladding techniques! This has allowed us to develop proprietary methods specifically designed for repairing all types of cast iron components.
Our laser cladding technique uses a laser beam to melt a powder or wire-based coating material. Afterward, it is bonded onto the surface of the cast iron component. This process results in a metallurgically bonded layer highly resistant to wear and corrosion.
Laser cladding offers several benefits over traditional welding techniques for repairing cast iron components. Unlike conventional welding, laser cladding requires minimal preheat, significantly reducing the time and cost associated with repairs. Additionally, the laser cladding process produces a much smaller heat-affected zone, reducing the risk of cracking during the repair process.
Trust Titanova to provide the laser cladding expertise to keep your operations running smoothly!
Contact us today to learn more about our services and how we can help you achieve your material processing goals.
Laser cladding and hard laser facing are welding techniques that provide a protective surface coating on metal parts. Also called laser metal deposition (LMD), laser cladding utilizes a focused laser beam to generate heat, and clad material is simultaneously fed into the resulting melt pool on the targeted surface area of a metal component. The result is a metallurgically bonded protective layer that enhances a component’s resistance to wear and corrosion associated with environmental and chemical factors. This is done with low dilutions and small heat-affected zones.
Such protection is particularly essential for components across the oil and gas industry. Part exposure to salt water, chemicals, oxidation, and temperature extremes takes a toll on metal components and can lead to downtime and productivity losses due to leakage or part failure. Learn more about the applications for laser cladding in this industry, and how it can help safeguard your equipment from corrosive service conditions.
Laser Cladding Applications in the Oil and Gas Industry
The oil, gas, and petrochemical sectors require parts that can withstand rugged applications in harsh environments. Applications for laser cladding in this industry include:
Bearings, bearing bushes, and bearing journals
Cutting and drilling components and tools
Gate and ball seats and valves
Heat exchangers
Hydraulic cylinders and plungers
Piston rods
Pump components
Risers
Rotors
Seals and seal seats
Tanks
Why Laser Cladding?
Due to corrosion problems in the oil and gas industry, its equipment components benefit greatly from a protective coating. Compared to standard additive methods, laser cladding provides a very low dilution corrosion- and erosion-resistant layer that extends part life and improves operational reliability and performance. Using lasers allows for greater precision and lower heat input that minimizes dilution, and distortion and enhances the properties of the metal substrate. As an added advantage, the process yields very thin weld overlays enabling part designers the choice to use generic base metal alloys for their parts.
All these advantages generate time and cost savings, as well. Covering a more affordable substrate with a thin, specialized surface coating can reduce material expenditures. Coated parts better withstand chemical exposure and mechanism wear, which prevents costly downtime and saves on maintenance and repairs. Offering shorter production times than plasma transferred arc (PTA) welding and other traditional techniques, laser cladding ultimately boosts productivity.
Titanova Laser Cladding
For minimal dilution, Titanova, Inc. uses a laser cladding method capable of welding a very smooth and thin single-pass metal layer overtop of a substrate at high rates of deposition. Stainless and tool steels, superalloys, chrome, cobalt, and nickel alloys are just some of the optimal metals for this process. Our technique allows us to successfully modify the surface metal’s chemistry without creating much weld distortion or a large heat-affected zone. With laser cladding, we can generate functional, cost-effective, and customizable components with enhanced resistance to wear, corrosion, oxidation, and high-temperature fatigue.
Founded in 2008, Titanova strives to provide products and services of the highest quality that meet or exceed customers’ expectations for 100% customer satisfaction. As a full-service ISO 9001:2015-certified laser job shop and certified member of ASME, ASM, AWS, and NTMA, we are committed to continual improvement, offering innovative laser processing solutions and supplying the thinnest and purest clads available in today’s weld overlay market.
For more information on our laser cladding services and how they can benefit your operation, contact us today.
Posted by John Haake on | Comments Off on Thermal Spray vs. Laser cladding
This blog is meant to explain the differences between the thermal spray and laser cladding processes and help you understand the physical differences between each process.
What is Thermal Spray?
Thermal spraying refers to a group of coating processes in which finely divided metallic or nonmetallic materials [ceramics] are deposited in a molten or semi-molten condition to form a coating. The coating material may be in the starting form of powder, ceramic rod, wire, or molten materials.
The basic process is shown in Figure 1.
Figure 1 – Basic Thermal Spray process
Since there are a large number of materials and heating methods, research has resulted in many different commercial application methods. In Figure 2, a schematic segregated by a thermal heat source method is shown. In general, the flame is chemical combustion and the electrical is a plasma arc.
Figure 2 – Thermal spray application methods
As can be seen from Figure 1, the heat source is disconnected from the workpiece and only affects the thermal spray material, therefore the adhesion of the thermal spray coating is mechanical and NOT welded. This naturally results in a very low heat process, which produces no distortion to the workpiece. On a microscopic level, the coatings are porous. Since the adhesion is mechanical, the coating thicknesses are limited to < 0.015” due to inherent internal stresses and are subject to spallation.
Thermal Spray and Fuse of Self-Fluxing Alloy Powders
Since thermally sprayed material is not metallurgical alloy-bonded to the substrate and the coatings are typically porous, the industry developed thermal spray powder chemistries that are self-fluxing. Self-fluxing alloy is the generic name given to the nickel- or cobalt-based thermal spray powders used to hard-face industrial parts subject to severe abrasion or corrosion.
The thermally sprayed workpiece is heated to a temperature that is at the melt temperature of the self-fluxing alloy, which is below the workpiece melt temperature. As can be seen, the self-fluxing process produces an alloy [welded] bond and eliminates porosity, and achieves thicker and harder coatings. Since the entire workpiece must be heated to a temperature of around 2000° F, this process is typically limited to minor distortion insensitive cylindrical parts.
What is Laser Cladding?
Laser Cladding, also known as laser weld overlay, laser additive manufacturing, direct laser deposition [DLD], and laser spray welding, is a welding process analogous to electrical arc welding processes such as GTAW, TIG, MIG, and PTA in which the heat source is co-located where the overlay material and the workpiece surface come in contact. The heat source is energetic enough to melt the coating material and a portion of the substrate to create a welded bond. Melting as little of the workpiece substrate as possible is beneficial with respect to distortion, intermetallic dilution, and structural defects.
The laser is the heat source, and the physical attributes of the laser are immediately recognizable when it comes to weld overlays. Lasers generate controllable optical energy that can be used to controllably modify materials. The lasers are controllable in terms of direction and beam shape. This process involves surface-only optical heating since the energy is pure radiation energy in the form of photons. This results in instantaneous heating, which enables instantaneous control. As previously mentioned, this process can create a weld overly with the smallest amount of heat input, resulting in the lowest amount of distortion, intermetallic dilution, and almost zero defects.
Benefits of Laser Cladding
The inherent benefits of laser cladding are:
Much less weld distortion = Less post-machining
Low dilution =
Less solidification cracking,
Less hard cracking
Meeting single pass chemical specifications
Less preheat = Less tempering
Thinner clad = Lower material costs and pre-machining costs
Smoother clad = Less post-machining
CONTACT THE LASER WELDING EXPERTS AT TITANOVA TODAY
If you’re looking for laser cladding, thermal spray, or other laser material processing services, consider Titanova. We have over 30 years of experience in the area. For information about our laser cladding capabilities, visit our laser cladding capabilities page or contact us today.
Posted by John Haake on | Comments Off on Introduction to the Laser Cladding Process
Laser cladding—also referred to as laser metal deposition or Laser weld overlay—is a manufacturing technique used to add metal material to the surface of a component. It is generally used to create a protective coating that increases the functionality of the part or product. However, it can also be used to repair worn or damaged surfaces.
The following blog post provides an overview of the laser cladding process, outlining how it works, typical applications, materials used, and key advantages.
How Does the Laser Cladding Process Work?
As suggested by the name, the laser cladding process involves the use of a laser. The laser scans across the surface of the workpiece, creating melt pools in targeted areas. At the same time, a stream of metallic powder or wire is introduced to the targeted areas, which allows the laser to melt the material. The short exposure time reduces the amount of heat and therefore the heat affected zone and enables the workpiece and coating material to cool quickly. The result is a metallurgically bonded coating layer that is tougher than one created using the thermal spray coating method and safer to create than one made through the hard chromium plating method.
Applications of the Laser Cladding Process
Since the laser cladding process can add protective coatings and restore worn/damaged surfaces, it finds use in many industries. For example:
In the construction industry, it is used to coat various machines and systems to protect them against corrosion, impact, and wear. The created coatings help extend the service life of the equipment, reducing repair and replacement costs for construction companies.
In the oil and gas industry, it is used to coat cutting and drilling tools. These components are regularly subjected to stresses that can reduce their service life without proper wear protection. The laser clad process increases the surface durability of the tooling, allowing it to withstand long-term use.
In the mining industry, it is used to coat hydraulic cylinders. The coatings on hydraulic cylinders are highly susceptible to corrosion in mining facilities, which can lead to leaks. Coatings created through the laser cladding process are longer-lasting than ones made through the chrome plating process, which can lead to significant cost savings over the years.
What Materials Can Be Used With the Laser Cladding Process?
The laser cladding process can be performed with a broad selection of metals, including, but not limited to, the following:
Aluminum alloys
Cobalt alloys
Copper alloys
Nickel (self-fluxing) alloys
Stainless steels
Superalloys
Titanium alloys
Tool steels
Click to Expand
Advantages of Laser Cladding
There are many advantages to using laser cladding over other coating methods. For example:
It allows for the precision positioning of coating materials, enabling coaters to target specific areas on the component.
It creates layers that are more impact resistant than ones made through the thermal spray coating method, which can lead to better protection for components.
It produces layers with little to no porosity, which creates denser (>99.9% density) coatings.
It requires relatively low heat input, generating a narrower heat-affected zone (HAZ).
It generates minimal distortion in the workpiece, reducing the need for post-coating processing.
It accommodates the use of laser power modulation technology, which allows for better thermal control.
Learn More About Laser Cladding From Titanova
Want to learn more about the laser cladding process? Ask the experts at Titanova! We have extensive experience providing laser processing solutions, including laser cladding, to customers across a wide range of industries. Our team can answer any questions and address any concerns you may have about the process.
Do you require a laser cladding partner for your next project? We are here to help! Equipped with customized diode lasers, we can create the thinnest and purest weld overlay possible. Check out our laser cladding service page to learn more about our capabilities.
