Armor steel denotes high-strength, quenched-and-tempered steels developed for protective tasks—such as in vehicles, doors, bulkheads, safes, or building components with increased resistance. In deconstruction, strip-out, and cutting operations, armor steel is encountered above all where armored components are integrated into concrete–steel composites. To gently expose, separate, and safely dismantle such composites, tools developed by Darda GmbH such as concrete pulverizers, hydraulic wedge splitters, steel shears, and portable demolition shears are used in combination with high-performance hydraulic power units—depending on construction, material thickness, and access conditions. The objective is always to perform material separation in a controlled, low-emission, and component-friendly manner.
Definition: What is meant by armor steel
Armor steel is a quenched-and-tempered protection steel with high hardness and simultaneously increased toughness. It is typically supplied as sheet or plate, exhibits Brinell hardness values of roughly 300 to over 500 HBW, and is produced by alloying (e.g., with Cr, Ni, Mo) followed by quenching and tempering that create a predominantly martensitic microstructure with sufficient impact toughness. Armor steel is used for ballistic and mechanical protection and is found in armor systems, armored doors, armor plates, bulkheads, bank vaults, and safety-related installations. Unlike structural steel or non-tempered fine-grain steels, armor steel is optimized for resistance to penetration, spall formation, and local deformation.
Material properties and microstructure of armor steel
The special feature of armor steels lies in the combination of hardness (to deflect penetrating bodies) and toughness (to absorb energy without brittle fracture). This balance is achieved through chemical composition and heat treatment and affects machinability, weldability, and separability during deconstruction. In mixed concrete–steel structures, it has a direct influence on the choice of tools and work steps.
Materials engineering: key values, microstructure, and impact on separation
Armor steel is often supplied as hardened and tempered plate. Typical characteristics include high yield strength, elevated tensile strength, a very fine microstructure, and pronounced surface hardness. This results in specific effects during deconstruction: Thermal cutting methods create a distinct heat-affected zone in which hardness and stresses can change; mechanical shearing and splitting require high surface pressures and dimensionally stable cutting edges. In composite structures made of armor plates, reinforcing steel, and concrete, exposing the steel body is decisive before targeted cutting or shearing can take place.
Relevance in concrete demolition and special demolition
Armored elements are found in safety-related rooms, bunkers, vault systems, vehicle components, or infrastructure parts with increased protection classes. When deconstructing such structures, controlled exposure, low-emission separation, and safeguarding adjacent components are essential. Concrete pulverizers enable selective “biting” of the concrete without excessively heating or damaging the armor plate. Hydraulic wedge splitters allow low-noise and low-vibration opening of massive concrete cross-sections. For the actual steel separation, steel shears, hydraulic demolition shears, Multi Cutters or—on large-format, tough armor plates—portable demolition shears are used, supplied by appropriately sized hydraulic power packs. In this way, the composite is gradually broken down into its material fractions.
Workability of armor steel: cutting, separating, and opening
The choice of method depends on thickness, hardness, accessibility, and boundary conditions (fire and spark risk, emissions, vibrations). Mechanical, hydraulic, and thermal methods are often combined—starting with exposing the steel in the concrete composite, followed by the actual steel separation.
Cold hydraulic separation methods (shearing and pressing)
Hydraulically driven steel shears, hydraulic demolition shears, and Multi Cutters enable cold cutting without thermal hardening of the cut edge. This is advantageous in confined spaces, sensitive environments, and when ignition sources must be avoided. Decisive factors include blade quality, cutting-edge geometry, and sufficient opening and cutting pressure, provided by robust hydraulic power packs. For particularly tough armor plate, a portable demolition shear with optimized cutting kinematics can be used.
Thermal separation methods
Where accessible and permissible, oxy-fuel or plasma cutting may be considered. Armor steel can, however, be prone to hardening and embrittlement in the heat-affected zone. Thermal methods should therefore only be used if the required boundary conditions (environmental protection measures, spark control, fire protection) can be met and the resulting edges will not be reloaded later. Mechanical alternatives are often preferable in security-sensitive deconstruction projects.
Mechanical preparation and exposure
Precise removal of surrounding concrete with concrete pulverizers minimizes loads and creates defined attack points for shears. In massive, low-crack cross-sections, hydraulic wedge splitters accelerate opening by initiating cracks and creating split lines. This makes armor plates or doors accessible without unnecessarily affecting the steel surface.
Process model for composite deconstruction involving armor steel
A structured approach reduces risks and increases efficiency when separating armored composites:
- Survey: Record material thicknesses, layer sequence (concrete–steel–concrete), fasteners, weld seams, coatings, and potential stored energy (prestressing, residual stresses).
- Exposure: Selectively remove concrete cover with concrete pulverizers; on massive components, create split lines with hydraulic wedge splitters.
- Preparation of cut interfaces: Mark, shore, and install retention and catch measures; create edge access for steel shears, hydraulic demolition shears, or portable demolition shears.
- Separation cut: Prefer cold shearing; use thermal methods only in suitable environments and after evaluating the heat-affected zone.
- Downsizing and separation: Dimension steel segments for haulage logistics, perform rebar cutting, and classify concrete debris.
- Rework and control: Inspect cut edges, avoid unacceptable hardening, and update documentation.
Tool selection: from concrete cover to steel cutting
The selection depends on material pairing, component thickness, and target geometry. Principles:
- Concrete cover ≤ 30 cm: Rapid biting with concrete pulverizers; pinpoint exposure of weld seams and bolted connections.
- Massive concrete cross-sections: Additionally use hydraulic wedge splitters to create openings with low vibration or to release core zones.
- Armor plate up to medium thickness: steel shears or hydraulic demolition shears with high cutting force; pay attention to blade wear resistance.
- Large-format, tough armor plates: portable demolition shears or specially designed Multi Cutters for controlled segmentation.
- Power supply: Suitable hydraulic power packs for consistent performance, short cycle times, and reproducible cutting results.
Typical challenges and practical solutions
Armor steel imposes special demands on cut guidance, blade tool service life, and operational safety. Common situations and countermeasures:
- Hardening and crack tendency on thermally cut edges: Prefer cold shearing; if heat input is unavoidable, keep the edge zone as small as possible and monitor for crack formation.
- Coated surfaces (paints, corrosion protection): Remove locally before cutting to reduce emissions and blade wear.
- Concealed fasteners (bolts, tabs): Expose selectively with concrete pulverizers; choose shear angles so that peak loads are managed.
- Large plates with residual stresses: Cut in stages, provide intermediate bracing, and plan segment sequences.
- Confined access: Use compact shear tools; employ splitting techniques to create additional working space.
Safety and regulatory framework
Work on armored structures requires heightened attention. General guidance: a qualified hazard analysis, suitable safety measures (fire protection, spark and fragment protection), organized ventilation for emissions, as well as a load and retention system concept are indispensable. In particularly sensitive environments or for components with possible prior military use, special permits, proofs, and documentation may be required. Legal requirements can vary by project and location; involving competent authorities is advisable in such cases. Statements here are general and not specific to individual cases.
Quality assurance in deconstruction involving armor steel
Robust documentation reduces risks and ensures traceability:
- Material identification focused on thickness, hardness range, and composite build-up
- Evidence of the selected separation methods and the tools used
- Inspection of cut edges, dimensional accuracy, and segment weights
- Tracking of disposal and recycling streams separated into steel and concrete
Disposal, recycling, and sustainability
Armor steel is generally well recyclable. The prerequisite is clean separation of concrete, reinforcement, and armor plates. Mechanical, cold-hydraulic separations promote high-quality scrap because they minimize the heat-affected zone. Concrete pulverizers and hydraulic wedge splitters support the material-pure separation of mineral fractions. Early coordination with disposal and recycling partners facilitates logistical planning of segment sizes and the transport route.
Distinction from structural steel and high-strength fine-grain steel
Structural steels are primarily optimized for workability, weldability, and load-bearing capacity in construction, while armor steels focus on penetration resistance, surface hardness, and controlled toughness. High-strength fine-grain steels can achieve similarly high strengths, but are not necessarily designed for ballistic requirements. These differences explain why deconstruction of armor steel requires different tool concepts—such as portable demolition shears and impact-resistant steel shears—as well as preparatory measures using concrete pulverizers and hydraulic wedge splitters.