Stainless steel welding – from the single part to the small batch
stainlesstec welds stainless steel for industrial and technically demanding applications. We make individual weldments as well as complex welded assemblies, combining high welding quality with our own sheet metal work and finishing.
This is about more than a durable joint: welding stainless steel properly means considering material, heat input, distortion, weld design, corrosion resistance and the later surface requirements together. That is exactly what our shop is set up for.
We make stainless steel weldments to drawing and CAD data – as one-offs, prototypes, small batches or recurring assemblies. Typical work includes:
Enclosures and panelling
Frames and load-bearing structures
Vessels and tanks
Machinery and plant components
Tube and sheet metal structures
Brackets and consoles
welded stainless steel sections
parts with high demands on visible surfaces
complete welded assemblies to drawing
We can laser cut, punch and bend the individual parts ourselves, which lets us align the pre-production work with the welded structure that follows.
Why stainless steel calls for particular care when welding
Stainless steel owes its corrosion resistance to a chromium-rich passive layer on the surface. Welding exposes that surface to high local temperatures. The quality of a stainless steel weld therefore depends on more than whether the joint holds mechanically. What matters includes:
Heat input
Too much heat enlarges the heat-affected zone, increases distortion and affects the properties of the surface.
Heat tint
Oxidation can leave heat tint around the weld. Depending on the application it then has to be removed properly and the surface treated accordingly.
Contamination
Iron particles on a stainless steel surface can impair corrosion resistance. Handling the material correctly in a clean working environment therefore matters a great deal.
Distortion
The material changes as it heats and cools again. With thin sheet, large areas or complex geometries in particular, this has to be allowed for in the design and the welding sequence.
Weld root
The reverse side of a weld can be just as decisive for quality and corrosion resistance. Where the requirements call for it, we protect it during welding by back purging.
Welding different stainless steel grades reliably
“Stainless steel” is not a single material: corrosion resistance, strength, temperature resistance and welding behaviour differ considerably from alloy to alloy. stainlesstec processes and welds a range of grades to suit the requirements of the part in question, among them:
1.4301 / AISI 304
The classic austenitic chromium-nickel steel, used for countless machine, plant and sheet metal structures. It welds well and is one of the most widely processed stainless steels.
1.4307 / AISI 304L
The low-carbon variant offers advantages in welded structures and is used above all where corrosion resistance around the weld matters.
1.4404 / AISI 316L
Its molybdenum content gives this grade greater resistance to certain corrosive media, which makes it attractive for demanding plant, pharmaceutical and process applications.
1.4571 / AISI 316Ti
This titanium-stabilised grade is used for welded structures and applications whose material and temperature requirements call for such an alloy.
Other stainless grades and special materials
We also process other weldable stainless grades. For special materials we match process, filler metal, heat input and any pre- or post-weld treatment to the specific material specification.
Base material and filler metal have to match
In stainless steel welding too, the choice of filler metal determines the properties of the finished joint. Mechanical requirements are not the only consideration – corrosion resistance, temperature loading and the conditions in service can all influence the choice.
Where different stainless grades are joined, or dissimilar joints arise, the combination has to be assessed accordingly.
For us, a high-quality stainless steel weld therefore begins with knowing exactly which material is being processed – not with striking the arc.
TIG welding of stainless steel
TIG welding suits high-quality, closely controlled stainless steel joints particularly well. Because welding current and filler metal are controlled independently, the process can be guided very precisely – an advantage with thinner material, demanding weld geometries and high-quality visible welds.
We therefore use TIG wherever controlled heat input and a clean weld finish matter most.
On some stainless steel joints it is not enough to shield only the visible face of the weld. With pipework, vessels and other structures that place high demands on the weld root in particular, the reverse side can be protected from oxygen during welding as well.
Back purging flushes that area with a suitable shielding gas, preventing heavy oxidation of the root. This matters especially when:
the weld root cannot be reached mechanically later on
there are high demands on corrosion resistance
internal surfaces have to be cleanly finished
media come into contact with the welded surface
Whether back purging is required depends on the material, the design and the later application.
Heat tint and corrosion resistance
Heat tint is not merely a cosmetic matter: it is caused by oxidation at high temperature, and the near-surface zone of the stainless steel changes in the process. In corrosion-critical applications, proper post-weld treatment may therefore be necessary.
Depending on part and requirement, that work may include machining the weld and a suitable surface treatment afterwards. What counts is that welding and the intended final surface condition are planned together.
Avoiding rust contamination
Despite its corrosion resistance, stainless steel can show rust where iron particles reach the surface. Such contamination can come from unsuitable tools, abrasives or contact with mild steel.
With demanding stainless steel parts, clean and material-appropriate processing is therefore an essential part of manufacturing quality – particularly in applications calling for corrosion resistance, hygiene or high-quality visible surfaces.
Controlling distortion when welding stainless steel
A technically perfect weld is of little use if the finished assembly no longer holds its dimensions. With more complex stainless steel structures we therefore consider, before welding starts:
Weld position and length
Welding sequence
Heat input
Material thickness
How the parts are fixtured
Structural stiffness
Shrinkage on cooling
Required tolerances of the finished assembly
With thin-walled enclosures, larger areas and multi-weld structures in particular, this experience is decisive.
Visible welds in stainless steel
On high-quality stainless steel structures the weld often remains visible. It then becomes part of the product quality rather than a purely technical joint.
We therefore match the weld finish and the subsequent surface work to the requirements of the finished part – relevant for enclosures, panelling, high-grade machine components and other visible structures.
Complete stainless steel welded assemblies
Our work does not stop at the weld: stainlesstec can make the stainless steel parts required and then build them into complete assemblies.
That keeps the decisive steps in one pair of hands. Fits, bend radii, joint preparation, welding sequence and surface requirements can all be aligned during production planning.
We make stainless steel weldments and assemblies above all for technically demanding applications, among them:
Machinery and plant engineering
Robust, dimensionally accurate components, frames, enclosures and special structures.
Pharmaceuticals and hygiene-critical applications
Parts with particular requirements for material, processing, surfaces and cleanability.
Aerospace and high-technology applications
Precise special parts and small batches with high demands on manufacturing quality and documentation.
Defence technology
Parts and assemblies to defined material and production specifications, with project-specific documentation requirements.
Which standards, records and documentation are required is settled for each individual project.
One-offs, prototypes and small batches
stainlesstec is geared to work that calls for flexibility and technical dialogue. We take on one-offs, prototypes, small batches and recurring welded assemblies.
With new parts in particular, talking early pays off: changes to weld positions, bend radii, joint locations or how a structure is divided up can simplify production while improving quality and repeatability.
Let’s talk about your project.
Send us your drawing or CAD data by email – together with material, batch size and your requirements. We will come back to you with a sound assessment.
