S355 – S690QL

Fine-grained structural steel

High-strength fine-grained structural steels up to S690QL enable lightweight, high-load constructions—demanding during welding and machining.

Properties Challenge Machining Machines Industries FAQ

Brief definition

Fine-grained structural steel

Fine-grained structural steels combine high yield strengths with good weldability. They range from S355N/M to high-strength, quenched and tempered grades like S690QL. Because they allow for higher strength with less material usage, they are used in crane, vehicle, and steel construction. During welding and machining, they require defined processes and coordinated tools.

S355N / S355M

S460NL

S690QL

Welding certificate up to S690QL

Properties

Density

7.85 g/cm³

like all steel grades

Yield strength

355–690 MPa

Minimum values, S355 to S690QL

Weldability

good to demanding

defined welding process

Machinability

medium

higher cutting forces

Machining

Challenge and solution

Challenge

Higher cutting forces

As strength increases, cutting forces and tool wear also increase.

Our Solution

Tailored tools

Tools and cutting data are matched to the grade and strength.
Challenge

Demanding welding

High-strength grades require defined welding processes and qualification.

Our Solution

Certified welding

Our welding certificate covers structural steels and fine-grained structural steels up to S690QL.

Machining

How we machine this material

We weld fine-grained structural steels up to S690QL at our own welding stations and subsequently finish-machine the assemblies on our gantry and traveling column milling machines. Tools and cutting data are tailored to the higher strength.

Welding up to S690QL (see certificate)
Finish-machining in a single setup
Cutting data tailored to strength

Manufacturing

Suitable processes

CNC Milling

CNC milling at FORMA Maschinenbau: Milled parts up to 24 m length, 5-axis simultaneous machining, and 5-axis milling for single parts and series from the Münsterland region.

Large-Scale Machining

Large-scale machining at FORMA: mechanical machining of large parts up to 24 m in length and 160 t load capacity – including welded fabrications up to S355.

Complete Machining

Complete machining at FORMA: Turn-milling, 5-axis simultaneous, welded construction, and assembly – all from a single source.

Welding

Welding at FORMA: Welded structures made of structural and fine-grained steel up to S690QL – including mechanical finish machining from a single source.

Machine allocation

Approved Fine-grained structural steel for

Gantry Milling Machine

Correa

Correa Verxa 17750

Component length

17,750 mm

Axes

4 axes

Size Class

Over 10 m

Technical Data →

Traveling Column Milling Machine

Soraluce

Soraluce FX24000

Component length

24,000 mm

Axes

5 axes

Size Class

Over 10 m

Technical Data →

Gantry Milling Machine

DMG MORI

DMG DMU340P

Travel X

3,400 mm

Axes

Simultaneous 5-axis

Size Class

2–10 m

Technical Data →

Applications

Where Fine-grained structural steel it is used

For us, quality is not just a word, but measurable reality. Through state-of-the-art testing equipment such as laser interferometers and 3D measurement technology, we ensure that every component precisely meets specifications.