Mild steel is a fundamental material for construction, deconstruction, and industrial manufacturing. Owing to its low carbon content, it is considered easily formable, weldable, and reliable in processing. Especially in the fields of concrete demolition and special demolition, building gutting and cutting, as well as in separating tanks and pipelines, mild steel appears as a structural steel section, steel sheet, steel pipe, or as reinforcing steel in reinforced components. For practical tool use, it is crucial how mild steel behaves under compression, tension, and shear—such as when using concrete pulverizers, steel shears, Multi Cutters, tank cutters, or hydraulic rock and concrete splitters from Darda GmbH, which often contribute to exposing, separating, or downsizing components.
Definition: What is understood by mild steel
Mild steel refers to low-carbon, unalloyed or low-alloy steels with a typical carbon content up to about 0.25%. This results in a predominantly ferritic–pearlitic microstructure with good ductility, moderate strength, and high toughness. Mild steel can be readily formed cold and hot and is generally excellent for welding. Typical fields of application are sheets and profiles for industrial hall and plant construction, beams in building and bridge structures, tanks, pipeline systems, and fasteners. In concrete construction, mild steel is found as reinforcing steel (rebar), anchor plate, and built-in component. Deconstruction and separation techniques play a central role because mild steel, while readily cut due to its toughness, imposes specific requirements on cutting edges, shear forces, and process control.
Material characteristics and typical properties
Mild steel combines a low to medium yield strength with high elongation at break. In practice, yield strengths are often in the range of about 200 to 320 MPa, tensile strength around 340 to 510 MPa—depending on grade, thickness, and fabrication condition. The low carbon content reduces hardenability, which lowers the risk of brittle cracking and improves weldability. At the same time, the tendency to plastic deformation under shear load increases, which can lead to rolling, burr formation, and springback during cutting. Surface coatings (e.g., hot-dip galvanizing) influence friction and cutting resistance, corrosion behavior, and emissions during thermal cutting. Therefore, the selection of suitable separating and splitting methods depends not only on strength but also on thickness, geometry, coating, and the current stress state of the component.
Mild steel in deconstruction: components, situations, particularities
In concrete demolition and special demolition, mild steel appears as reinforcement, as support columns, beams, brackets, as machine foundation with built-in components, as guardrails, cable route supports, or as tank and pipeline material. In building gutting projects, light to medium steel components made of mild steel are selectively removed. In rock excavation and tunnel construction, mild steel components are found in protective linings, support frame, and installations. In natural stone extraction, mild steel work frequently concerns machine frames, service tanks, and pipelines.
Exposing and separating in composite with concrete
Concrete pulverizers from Darda GmbH are used to crush concrete and separate concrete parts from reinforcing steel. Mild steel reinforcement tends to be pulled along and bent during biting. A controlled bite with metered hydraulic power and a sequential approach (first weaken the concrete, then separate the reinforcement) reduces burr formation and undesirable deformations. Hydraulic wedge splitters for stone and concrete help open massive concrete bodies along defined lines so that the reinforcement becomes specifically accessible.
Components made of mild steel in steel structures
Profiles, sheets, angles, and pipes made of mild steel are standard in steel building construction. Dedicated steel shears for mild steel and Multi Cutters are used for their dismantling. The toughness of mild steel demands sharp cutting edges and sufficient hydraulic pressure to produce a clean shear line. For thick plates and pipes, pre-forming or pre-cutting (e.g., making starter cuts) is helpful to maintain control and minimize springback.
Vessels, tanks, and pipelines
Many tanks and pipelines consist of mild steel. Tank cutters are used to safely open shells, dismantle stiffeners, and cut out internal fittings. In potentially ignitable environments, cold cutting methods are advantageous. Coatings, residual media, and deposits affect cutting forces and emissions—a competent assessment before starting work is essential.
Processing mild steel: cutting, biting, splitting
Mechanical separation of mild steel depends on the balance of edge hardness, cutting geometry, tool stability, and matched hydraulic power. Devices from Darda GmbH, such as concrete pulverizers, steel shear, Multi Cutters, or tank cutters, are selected and operated according to design and material thickness.
Cutting with steel shear and Multi Cutters
When shearing mild steel, expect plastic deformation before and after the shear line. A tight shear gap, sharp blades, and a straight force path reduce the risk of buckling. Multi-layer sheets should be decoupled to avoid uneven loads. For profiles, V-seats and contoured blades facilitate secure gripping.
Biting reinforcement with concrete pulverizers
Concrete pulverizers separate concrete and grip reinforcement bars. For repeated cuts in mild steel, it is advisable to expose the reinforcement so the cutting area lies flush. Avoid excessive lever forces on the pulverizer; instead, work in small steps to prevent jamming.
Splitting instead of sawing
Hydraulic wedge splitters for stone and concrete generate wedge-shaped stresses in the concrete material and open the cross-section without immediately cutting the reinforcement. This enables an orderly sequence: first widen the component, then cut the exposed mild steel specifically with steel shear or Multi Cutter.
Influence of material and geometry on tool selection
Mild steel presents different requirements depending on thickness and component geometry. The choice between concrete pulverizer, steel shear, Multi Cutter, combination shear, or tank cutter depends on accessibility, material condition, and required cut quality.
Hydraulic power packs and performance matching
Hydraulic power packs supply the flow and pressure that determine working speed and shear force. For tough mild steels, a stable pressure supply with sufficient oil flow is recommended; using matching hydraulic power units helps keep the cutting motion even. Too low speeds increase friction and burr formation, while excessive load cycles promote wear. A tuned combination of power unit and tool minimizes temperature spikes and material deformation.
Rock splitting cylinders and combined workflows
Rock splitting cylinders allow massive components to be opened in a controlled manner. Combined with steel shears, this creates an efficient workflow: split, remove sections, cut reinforcement. This sequence reduces the risk of shears jamming in inaccessible spots or reinforcement smearing with composite residues.
Material identification and condition assessment before cutting
A reliable assessment of the material prevents poor tool choices and increases occupational safety.
Practical identification tips
- Appearance and magnetism: Mild steel is ferromagnetic and usually shows uniform, matte metallic surfaces beneath coatings.
- Spark test: The spark pattern can indicate low-carbon steels; requires experienced application.
- Markings and component documentation: Notes on grade and thickness provide clues to cutting forces.
- Hardness impression: Local indentation checks indicate ductility and strength level.
- Mobile analytics: In case of doubt, a competent material analysis is recommended, especially for safety-critical components.
Stress state and residual media
Stiffened plates, profiled material, and multi-layer composites often exhibit residual stresses. When opened, components can give way abruptly. Tanks and pipelines must be completely emptied, cleaned, and depressurized before cutting; any remaining media or gases are a safety risk.
Fields of application: mild steel in practical environments
Mild steel appears in all relevant application areas of Darda GmbH—from building gutting through special demolition to tunnel construction. A structured approach facilitates processing.
Concrete demolition and special demolition
- Components: Reinforcement, built-in components, anchor plate, brackets.
- Procedure: Crush concrete with concrete pulverizers, expose reinforcement, cut specifically with steel shear or Multi Cutters.
- Notes: Knock off concrete residues from the reinforcement before cutting to protect cutting edges.
Building gutting and cutting
- Components: Light to medium profiles, route supports, guardrails, sheet cladding.
- Procedure: Dismantle in sections, secure load-bearing parts, adjust cross-sections with combination shears.
- Notes: Coatings (e.g., zinc, paint) affect friction and cut appearance.
Rock excavation and tunnel construction
- Components: Support frames, anchors, linings made of mild steel.
- Procedure: Expose, release, cut into transportable pieces.
- Notes: Confined spaces require slim tools and cautious cutting guidance.
Natural stone extraction
- Components: Machine frames, service lines, tanks for auxiliary media.
- Procedure: Dismantle plant components, open tanks using cold methods.
- Notes: Observe dust and spark control in sensitive environments.
Special operations
- Components: Special structures, temporary support systems, auxiliary frames.
- Procedure: Individual planning, trial cuts for performance assessment.
- Notes: Process unknown grades conservatively at first until the material behavior is reliably assessed.
Cut and surface quality: what mild steel requires
Due to its toughness, mild steel often forms draw beads and burrs on the exit side. For a clean cutting edge, the following help:
- Sharp, correctly adjusted blades with an appropriate shear gap.
- Constant feed rate and sufficient hydraulic pressure.
- Expose and support the component to avoid vibrations.
- Sectional cutting for large cross-sections to distribute load.
- Post-processing only when functionally necessary to save time and tools.
Occupational safety: general notes
Safety takes precedence. The following points are general in nature and do not replace an object-specific hazard assessment:
- Ensure structural stability before separating load-bearing mild steel components.
- Account for stress release: components can swing out suddenly when cut through.
- For tanks and pipelines: completely remove residual contents, avoid possible ignition sources, check atmospheric conditions.
- Use personal protective equipment, secure the splash and fragment zone.
- Operate tools only within approved operating parameters and inspect them regularly.
Recycling and material flow management
Mild steel is highly recyclable. For high recycling quality, clean separation from adherences (concrete, coatings, composites) is crucial. In concrete demolition, selective crushing with concrete pulverizers facilitates sorting of concrete debris and reinforcing steel. In building gutting and tank cutting, separate fractions (steel, non-ferrous metals, coating residues) are advisable. Careful sorting increases the value of scrap and reduces disposal costs.
Typical mistakes and proven countermeasures
- Insufficient hydraulic power: leads to draw burrs and rough cuts—match power unit capacity and tool size to material thickness.
- Cutting through composite without exposure: increases wear and risk of jamming—open the component first, then cut the steel.
- Underestimating residual stresses: can cause sudden springing open—stagger cuts, secure the component.
- Ignoring coatings: they influence friction and emissions—adapt cutting strategy and safety measures.
- Confusion with higher-strength steel: leads to overload—verify material, perform a trial cut.
Terminology and classification
Mild steel is not equivalent to high-strength or quenched-and-tempered steels. It is characterized by lower carbon content, good weldability, and high formability. In construction, the term “structural steel” is often used; many of these steels fall into the mild steel group. Reinforcing steel can—depending on standard and grade—have similarly low carbon content but is optimized as rebar for bond with concrete. For the practice of Darda GmbH, the distinction matters because cutting forces, tool selection, and the sequence of work steps depend on it.
Planning and execution of cutting work on mild steel
Structured planning improves quality, safety, and cost-effectiveness. The following has proven effective:
- Object analysis: material, thicknesses, coatings, composites, stresses.
- Method selection: concrete pulverizers for composite separation, steel shear/Multi Cutters for cross-sections, tank cutters for hollow bodies.
- Performance matching: tune hydraulic power pack and tool to each other.
- Cut sequence: secure the component, create accessibility, stagger cross-sections.
- Post-processing: check edges, ensure material-pure fractions.
Practice-oriented notes for special situations
Tight spaces and overhead work
Compact tools with high power density facilitate cutting in confined areas. Overhead, consider kickback and falling parts; keep sections small and plan safe catch zones.
Thick plates and nodes
For thick-walled components and nodes with multiple overlaps, a stepped approach helps: make notches, release edges, cut the core. This keeps the shear line controlled and protects tool tips.
Corrosion and aging
Corroded mild steel may be locally thinned and yield unevenly. Before cutting, set up adequate bearing supports and restraints to prevent uncontrolled movement.