Hardfacing welding wire
Classification by Material and Composition
1. Iron-based Hardfacing Welding Wires
Iron-based hardfacing welding wires are the most widely used hardfacing materials, which are further divided into the following types:
Pearlitic steel hardfacing wires: Mainly applied to repair workpieces under low-stress wear, such as shafts and gears. The hardness of the overlay ranges from 20 to 40 HRC. It features good machinability and excellent toughness.
Martensitic steel hardfacing wires: The overlay forms martensitic structure after quenching, with a hardness of 40 to 60 HRC. It offers good wear resistance and is suitable for workpieces under medium and high-stress wear conditions, including crusher roll shells and excavator bucket teeth.
High-chromium cast iron hardfacing wires: Made of high-alloy cast iron with chromium content of 15% to 30%. A large number of hard chromium carbide phases precipitate in the overlay, delivering a hardness of 55 to 65 HRC. This type boasts outstanding wear resistance and certain corrosion resistance, and is the most commonly used hardfacing wire in mining and metallurgy industries.
2. Nickel-based Hardfacing Welding Wires
With nickel as the matrix and chromium, molybdenum, boron and other alloying elements added, the overlay of nickel-based hardfacing wires has excellent corrosion resistance and high temperature resistance. Its hardness is generally 30 to 50 HRC, and the toughness is better than that of high-chromium cast iron overlays. It is widely used for hardfacing of parts requiring resistance to corrosion and high-temperature corrosion, such as valve sealing surfaces, chemical containers and steam turbine blades. Its price is much higher than that of iron-based wires.
3. Cobalt-based Hardfacing Welding Wires
Taking cobalt as the major alloy element, these wires possess superior hot hardness, corrosion resistance and thermal fatigue resistance. They can work continuously at 600℃ to 800℃. They are mainly used for high-end working conditions such as high-temperature valves, hot forging dies and turbine blades. Due to the high cost, their application scope is relatively limited.
4. Tungsten Carbide Hardfacing Welding Wires
Tungsten carbide particles serve as hard phases and are combined with the metal matrix. The overlay reaches a hardness of 60 to 70 HRC, and its wear resistance is 2 to 3 times that of ordinary high-chromium cast iron overlays. It is primarily used for components suffering from severe low-stress abrasive wear, such as shield machine cutterheads, dredger cutters and coal chutes. Its main disadvantage is high brittleness and poor impact resistance.
Classification by Manufacturing Process and Form
1. Solid Hardfacing Welding Wires
Manufactured through alloy smelting and wire drawing, solid hardfacing wires feature uniform and stable composition, simple production process and low cost. They are mostly used for gas shielded welding and submerged arc welding.
2. Flux-cored Hardfacing Welding Wires
This type of wire has a mild steel outer sheath filled with alloy powder, arc stabilizers, deoxidizers and other components. The performance of the overlay can be flexibly adjusted by modifying the powder formula. It has high deposition efficiency, stable welding arc and smooth weld appearance. As the fastest-developing product in the hardfacing industry in recent years, its market share has gradually surpassed that of solid wires.
Classification by Welding Method
They are classified into gas-shielded hardfacing wires, submerged arc hardfacing wires, self-shielded hardfacing wires and gas tungsten arc hardfacing wires. Among them, self-shielded hardfacing wires require no external shielding gas, making them ideal for outdoor on-site construction and widely applied in the field repair of large workpieces.
Selection Principles for Hardfacing Welding Wires
The selection of hardfacing welding wires shall take three core factors into comprehensive consideration: working conditions, cost budget and post-processing requirements.
Selection based on wear type and service conditions
Low-stress abrasive wear: Prioritize high-chromium cast iron wires or tungsten carbide wires, such as LZ60 and D60.
Medium and high-stress impact wear: Choose martensitic steel wires which balance toughness and wear resistance, such as D50 and 414N.
Corrosive and high-temperature service: Select nickel-based or cobalt-based wires, including ERNiCrMo-4 and Stellite 6.
Dimensional restoration of shafts and gears: Adopt pearlitic-martensitic steel wires to ensure good machinability.
Selection based on cost budget
Iron-based wires are generally priced at 10~50 RMB per kilogram, nickel-based wires at 100~300 RMB per kilogram, and cobalt-based wires over 500 RMB per kilogram. On the premise of meeting performance requirements, iron-based wires are preferred to cut costs.
Selection based on post-processing requirements
If machining is required after hardfacing, use pearlitic or martensitic wires with hardness below 45 HRC. If the workpiece can be put into direct service without further processing, high-hardness and high-wear-resistance wires are recommended.
IV. Notes on the Use of Hardfacing Welding Wires
Workpiece pre-treatment
Remove oil, rust and fatigue layers from the workpiece surface before hardfacing to prevent defects such as porosity, slag inclusion and overlay peeling. For cracked used workpieces, all cracks must be completely eliminated prior to welding.
Preheating and slow cooling
When using high-hardness wires for workpieces thicker than 20 mm, preheat the workpiece to 150℃~300℃. Apply thermal insulation for slow cooling after welding to avoid cracks in the overlay. This measure is particularly essential for martensitic and high-chromium cast iron overlays with high hardening tendency.
Control of hardfacing parameters
Adjust welding current and voltage according to wire diameter. For a 1.2 mm diameter flux-cored wire used in gas shielded welding, the current is normally set at 200~300 A and voltage at 25~30 V. Excessively high current will burn out alloy elements and impair the performance of the overlay.
Dilution rate control
Adopt low heat input during hardfacing to limit base metal penetration and reduce dilution, so as to keep the alloy composition of the overlay in line with design standards. Generally, 2 to 3 overlay passes are sufficient to meet performance requirements.
Safety protection
Welding fume and arc radiation are generated during hardfacing. Operators shall wear dust masks and welding helmets, and ensure adequate ventilation at the workplace.
V. Development Trends of the Hardfacing Wire Industry
Flux-cored wires replacing solid wires
Featuring flexible composition adjustment, high deposition efficiency and good weld formation, flux-cored hardfacing wires are gradually replacing traditional solid wires, with their market share growing steadily.
Development towards high performance
Demand for special hardfacing wires with superior wear resistance, corrosion resistance and high-temperature resistance for extreme working conditions keeps rising. Tungsten carbide reinforced and nano-reinforced hardfacing wires have been gradually put into industrial application.
Eco-friendly development
Low-fume and low-toxicity hardfacing wires are being developed to reduce harmful components in welding fume and comply with environmental regulations.
Matching intelligent technologies
Special hardfacing wires tailored for automated production are developed to cooperate with automatic hardfacing equipment and welding robots, so as to improve production efficiency and quality stability.
Company Introduction
Tangshan Runxing Machinery Co., Ltd., a professional manufacturer located in Tangshan, Hebei Province that focuses on R&D, production and on-site construction service of hardfacing wear-resistant metal products, was founded in 2010.
Our main products include chromium carbide overlay (CCO) wear plates, custom processed wear liners, wear-resistant pipes and pipe fittings, hardfacing flux-cored welding wires, automatic hardfacing welding machines, and professional roller surfacing repair service. We follow the business idea of “Integrity, Superior Quality, Innovation & Sustainable Development” and own mature advanced metal surface hardfacing technology.
We provide customized wear-resistant solutions for cement, steel, mining, port and dredging industries around the world, and have gained good market reputation in Russia and Central Asia.
All export business is fully authorized and handled by Hebei Yuwan International Trade Co., Ltd. This trading company completes all export work including customs clearance, shipment, documents and payment collection. Our factory focuses on product development and production to ensure stable product quality and on-time delivery.
Runxing Machinery sincerely hopes to establish long-term cooperation and achieve mutual benefit with you!
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FAQ
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