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VAL1LC- Ferritici

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Valbruna Grade

VAL1LC

Steel type

Ferritic Stainless Steel

Description of material

VAL1LC is a low Chromium ferritic stainless steel stabilized with Niobium with a smaller Nickel content than the similar grade VAL1LCNI.

Applications

This grade should be only used in mildly corrosive conditions such as fresh water pump shafts, washing machines and kitchen household items, screws and bolts manufacturing. In addition, it can also find applications in electromagnetic devices, electromagnetic switches and relays, and sensors where free machining ferritic grades cannot be used. VAL1LC is also used in some automotive applications but, as with most ferritic stainless steel grades, suffers with sub -zero embrittlement in cryogenic applications.

Corrosion resistance

VAL1LC has a good resistance to mildly corrosive environments but doesn’t offer the high temperature oxidation resistance typical of higher Cr-alloyed ferritic and austenitic grades. In certain aggressive atmospheric conditions it wouldn’t warrant a sufficient staining resistance. Therefore, evaluations should It should be done in cases where aesthetic performances were a primary requirement. Pitting and crevice corrosion may appear in the case of chloride solutions however this grade offer a good intergranular corrosion resistance thanks to its low C and Nb contents. It should be noted that this grade, as for every kind of stainless steel, surfaces should be free of contaminant and scale, heat tint, and passivated for optimum resistance to corrosion.

Cold working

This grade is suitable for cold heading, up-setting, and cold drawing and cold forming.

Machinability

VAL1LC has a machinability typical of all low Ferritic not micro–resulphured grades. Productivity gain depends on the types of machines used, the kind of tools used and their geometry, cutting fluids and the kind of machine operations on the pieces produced. Its structure influences the surface finish (roughness) and the chip morphology. Within certain limits, a little bit harder structure typical of annealing + cold finishing operations (such as cold drawing) offers advantages in some machine operations and better surface roughness.

Weldability

It should be noted that this grade, as for every kind of ferritic structure, produces large grain structures in FZ and HAZ caused by high temperatures of welding with some risk of embrittlement at room or lower temperatures. Austenitic fillers, in order to increase the ductility of the weld, don’t solve the problems in HAZ unless a PWHT is applied, even if VAL1LC offers a better ductility after welding when compared to typical ferritic grades. A PWHT restores the ductility in the case of Martensite formation and diffuses back the Chromium into the depleted zones close to grain boundaries restoring its resistance corrosion in addition to that typical resistance widely warranted by Nb stabilization. Autogenous high energy welding shouldn’t form any martensitic structure in the fused zone thanks to the low content of Carbon, and Nitrogen. PWHT could also be avoided in many cases. To avoid a ductility decrease in the weld, shielding gases such as Hydrogen and Nitrogen must not be used. Argon and Helium are the preferred choices. In any case, all welding procedures should apply and maintain low heat input processes.

Hot working

VAL1LC has a very good hot plasticity thanks to a wide range of possible forging temperature. Avoid overheating and long soaking since this could cause grain growth. The last final steps of forging must be carried out at a lower temperature range with a suitable reduction in order to obtain a structure with fine and uniform grains. Large blooms and ingots may require a suitable preheating to avoid cracks and an air cooling after forging. Overheating must always be avoided in order to reduce the risk of internal bursts and a structure with large coarse grains. An annealing after forging should be always be performed in order to restore both a better corrosion resistance and enhance the ductility.

Designations

UNS S40940
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