Welding consumable

Welding consumable is a central topic in the context of concrete demolition, special demolition, and rock processing. Whether in manufacturing, maintenance, or wear protection of carrier machines and gripping or cutting components: the choice of the suitable consumable determines service life, operational safety, and cost-efficiency. In the products of Darda GmbH—such as concrete demolition shear, rock and concrete splitters, combination shears, Multi Cutters, steel shears, tank cutters, hydraulic power pack, and stone splitting cylinders—high static and dynamic loads, abrasion from rock and concrete, as well as varying temperatures and humidity act simultaneously. A suitable welding consumable helps avoid cracks, properly regenerate edges, and reliably join highly loaded assemblies.

Definition: What is meant by welding consumable

Welding consumable (also welding filler metal or consumable) refers to materials fed into the joint area during welding or hardfacing. They create weld or overlay layers, bridge gaps, and ensure the required mechanical properties of the joint. Common forms are stick electrodes, solid wires, flux-cored wires, and powders/fluxes for special processes. Composition and properties—such as strength, toughness, hydrogen content, and chemical analysis—are chosen to match the base material, the loading, and the welding process.

Importance of welding consumables for concrete demolition shear and stone and concrete splitters

Concrete demolition shear as well as stone and concrete splitters operate at the boundary between mechanical force transmission and highly abrasive contact with concrete, reinforcement, and rock. Welding consumables are primarily used here for three tasks: safe joining of load-bearing structures, professional repair of cracks and edges, and hardfacing for wear protection. An unsuitable consumable can lead to quench cracks, insufficient toughness, or premature edge wear. A suitable, preferably low-hydrogen welding consumable with matched strength and notch impact toughness significantly increases the operational reliability of gripping arms, blade holders, housings, and bearing mounts.

Material types and welding processes

The selection of the welding consumable is closely tied to the process. In the repair of demolition tools, the following combinations are common:

• Manual shielded metal arc welding with stick electrodes: robust, tolerant of dirt and tight positions; a good option for on-site work and thick-walled components.
• MAG welding (metal active gas) with solid wire: high deposition rate, economical in series and workshop fabrication.
• Flux-cored arc welding: self-shielded or gas-shielded flux-cored wires; practical for thick sections, hardfacing, and all-position welding.
• TIG welding: precise control of penetration, suitable for root and repair welds when top weld quality is required.

For hardfacing on jaw edges, guides, or impact surfaces, wear-resistant flux-cored wires and electrodes are customary. For load-bearing welds in booms, brackets, and housings, tough, low-hydrogen consumables are used that match the base material (often quenched and tempered fine-grain steels).

Selection criteria for welding consumables in concrete demolition and special demolition

The conditions in concrete demolition, building gutting, and rock excavation require targeted selection. Key criteria are:

• Strength and toughness: matching or slightly undermatching tensile strength, sufficient notch impact toughness—especially at low temperatures.
• Hydrogen content: low diffusible hydrogen to minimize cold cracking in stressed, thick-walled components.
• Compatibility with base materials (e.g., fine-grain steels, wear-resistant steels, cast materials) and heat-affected zones.
• Welding position and component thickness: choice of diameter, type, and process stability for PA–PF.
• Wear mechanism: abrasion from rock/concrete, mixed wear with impacts, possibly corrosion—hardfacing chemistry tailored to that.
• On-site suitability: moisture resistance, ignition behavior, low spatter, arc stability.

Hardfacing on gripping and cutting zones

In concrete demolition shear, steel shears, combination shears, Multi Cutters, and tank cutters, edges and contact faces are constantly loaded. A hardfacing overlay can significantly increase service life if the build-up matches the load case:

• Chromium carbide-filled overlays for high abrasion resistance against concrete and rock.
• Martensitic or metal matrix overlays for mixed loads with impacts.
• Multi-layer strategies: tough buffer layer to relieve stresses, wear-hard top layer above.

Controlled heat input is essential. Excessive interpass temperatures promote dilution and reduce hardness; too low temperatures increase crack risk. Edges are often built up in segments to control shrinkage stresses.

Welding consumables for high-strength and thick-walled components

Frames and cylinder mounts of stone and concrete splitters as well as housings of the hydraulic power pack are often made of quenched and tempered fine-grain steels or thick-walled structural steels. The following are required:

• Low-hydrogen consumables (e.g., basic electrodes, suitable flux-cored wires) with low moisture pickup.
• Matched strength (matching or slightly undermatching) to avoid brittle weld areas.
• Sufficient notch impact toughness in weld and heat-affected zone for alternating loads.

For cast repairs (e.g., brackets, claws), nickel-bearing electrodes or specially alloyed flux-cored wires are common, often with moderate preheating and short beads to minimize stresses.

Processing: preheating, interpass temperature, and post-treatment

Proper temperature control is a key factor for crack-resistant joints:

1. Preheating for thick-walled, high-strength, or constrained geometries reduces cooling rates and hydrogen-related risks.
2. Maintain interpass temperature within the recommended range; too high reduces toughness and hardness, too low promotes cold cracking.
3. Post-heating/stress relief is useful depending on the material group; in hardfacing, it is usually limited to preserve wear hardness.

Basic stick electrodes should be stored dry and re-dried as needed. Flux-cored wires must be protected from moisture. A short arc and appropriate heat input (heat input) improve microstructure and toughness.

Quality assurance and testing

To ensure welding consumables fulfill their task, simple yet consistent quality assurance is advisable:

• Batch documentation of the welding consumable and proof of storage conditions.
• Visual and dimensional inspection of the weld, followed by suitable non-destructive testing (e.g., dye penetrant, magnetic particle testing) in safety-relevant zones.
• Hardness testing on hardfacing overlays and in the heat-affected zone to avoid embrittlement.

In practice, tests are selected to match the loads on components in concrete demolition shear, steel shears, stone splitting cylinders, and brackets.

Application-specific aspects

Concrete demolition and special demolition

High load cycles and impacts require tough, low-hydrogen consumables. Hardfacing protects gripping and cutting edges against abrasion from concrete and reinforcement. For repairs on concrete demolition shear, buffer layers beneath hard top layers are proven.

Building gutting and cutting

In combination shears, steel shears, Multi Cutters, and tank cutters, cutting edges and guideways are critical. Overlay welding with an impact-resistant alloy keeps edges stable without becoming too brittle.

Rock excavation and tunnel construction

In rock demolition and tunnel construction, rock contact causes intense abrasion. Chromium carbide-rich hardfacing overlays and tough intermediate layers are advantageous. For stone and concrete splitters, load-bearing welds on housings and mounts require particular monitoring.

Natural stone extraction

Uniform yet abrasive loading: hardfacing with good abrasion resistance and sufficient bonding strength. For stone splitting cylinders, dense, crack-free welds are important to prevent stress cracking.

Special applications

Unusual materials or media (e.g., humid environments) require adapted consumables and careful drying to prevent moisture pores and cold cracking.

Typical applications and weld designs on Darda GmbH products

• Concrete demolition shear: crack repairs on gripping arms, hardfacing at edges, reinforcements on bearing lugs.
• Stone and concrete splitters: welds on housings, brackets, and mounting interfaces; buffer layers on contact faces.
• Combination shears, steel shears, Multi Cutters: regenerating blade seats, bevel build-up, segmented edge build-up.
• Tank cutters: dimensionally accurate repairs on beams and guide parts; low-spatter processes preferred.
• Hydraulic power pack: welding on frames, guard and carrier structures, with controlled heat input away from sensitive seals.

Process reliability, occupational safety, and environment

For safe results, suitable fume extraction, personal protective equipment, and a clean welding zone are essential. Manufacturer specifications for welding consumables—especially processing temperatures, drying, and interpass temperatures—should be observed. On construction sites, a ground connection close to the weld is advisable so welding current does not pass through bearings or hydraulic components.

Storage, drying, and handling of welding consumables

• Dry, moderate storage prevents moisture pickup and hydrogen problems.
• Re-drying of basic electrodes according to the manufacturer’s specifications.
• Clean feeding of wires, intact wire feed, dry shielding gases.
• Labeling of coils/packages and separation of material types to avoid mix-ups.

Failure patterns and remedies

• Pores: moist consumables, insufficient surface preparation—improve drying, clean the component, check gas flow.
• Cracks: excessive hardness/stress, insufficient preheating—ensure low hydrogen, use buffer layers, adjust temperature control.
• Insufficient wear resistance: incorrect hardfacing chemistry or excessive dilution—review top layer choice, reduce heat input, apply multilayer build-up.

Normative guidance and documentation

Recognized standards for consumables (e.g., EN ISO 2560 for stick electrodes, EN ISO 14341 for solid wires, EN ISO 17632 for flux-cored wires) serve as non-binding guidance. The technical data sheets of the specific welding consumable and documented procedures tailored to the component and application always prevail.

Practical recommendations for durable repairs

1. Analyze the component: determine base material, thickness, restraint, crack cause, and wear mechanism.
2. Select the welding consumable: tough, low-hydrogen for load-bearing zones; wear-hard with buffer layers for edges.
3. Plan joining/hardfacing: segment welds, control heat input, check interpass conditions.
4. Rework: profile edges, round transitions, perform finish grinding if needed to reduce stresses.
5. Inspect and document: visual/NDT inspection, hardness checks, temperature log for critical repairs.

Properly selected and processed welding consumables make a decisive contribution to ensuring the function of concrete demolition shear, stone and concrete splitters, and other tools from Darda GmbH in demanding service—from concrete demolition to tunnel construction to natural stone extraction.