Corrosion testing of cutting fluids on metal alloys

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Preventing corrosion caused by cutting fluids

The cutting fluids contribute to lubrication, cooling and chip removal during machining operations. However, their composition, concentration, ageing or the presence of contaminants may promote the appearance of stains, pitting, oxidation or localized attacks on metal parts. This damage may compromise the surface appearance, assembly, functional performance or compliance of finished parts.

The corrosion tests for cutting fluids assess the interaction between a fluid and a material representative of your production: steel, stainless steel, aluminium, copper, brass, titanium or a specific alloy. Filab laboratory supports manufacturers in objectively investigating an observed defect, comparing several formulations or qualifying a fluid before its deployment in production.

Identifying surface degradation mechanisms

Defects observed after machining or storage can take different forms: uniform corrosion, pitting, halos, tarnishing, blackening, deposits or colour variations. Their examination must take into account the metal grade, surface treatments, part geometry and successive process steps.

Filab laboratory can compare an altered area with a reference area and document the morphology of the defects. This approach helps distinguish an attack on the metal substrate from a surface deposit and prioritize hypotheses related to the fluid, rinsing, drying or storage.

Collecting the data required for the protocol

To prepare the test, it is useful to specify the alloy designation, known metallurgical condition, any surface treatment, fluid reference, use concentration and application method. Information about the machining operation, rinsing, drying and storage conditions also helps align the protocol with the situation encountered.

In the event of non-compliance, providing affected parts, reference parts and a fluid sample facilitates comparison. Filab laboratory then defines the test conditions and observation criteria in line with your objective: diagnosis, fluid comparison or internal validation.

Setting up a controlled comparison of formulations

Comparing several fluids requires keeping the parameters that may influence corrosion identical: material, surface preparation, concentration, applied volume, contact time and exposure conditions. Each formulation is then evaluated on comparable specimens, using observation criteria defined in advance.

This approach makes it possible to compare new fluids, fluids in service or different use concentrations. It is particularly useful when changing suppliers, modifying a formulation or introducing a new metal grade.

Defining a test suited to your operating conditions

A relevant protocol is based on the joint definition of the fluid-material pair, surface condition, working concentration, contact time, and exposure environment. Test specimens can be prepared from parts, coupons, or representative metal grades.

Filab laboratory designs tests on metal alloys according to your industrial challenge: immersion, fluid deposition, contact under humidity, or exposure cycles. Observations before and after testing are combined, when necessary, with surface analyses to characterize the affected areas and guide corrective actions.

Filab laboratory also supports you with the following services:

Characterizing the fluid and corrosion residues

The investigation may combine visual and microscopic observation with elemental identification of suspicious areas. The results help detect residues from the fluid, corrosion products or contaminants introduced during the process.

When understanding the material is necessary, Filab laboratory also draws on its expertise in refractory alloy characterization and metallurgical analysis. Interpretation is carried out in light of the production history provided by the client.

Choosing specimens representative of production

The choice of specimens directly affects how representative the results are. Material coupons, machined parts or samples with the same surface condition may be selected depending on the issue. A ground, polished, turned or coated surface will not necessarily react in the same way when in contact with a fluid.

Material characteristics can be supplemented by ISO 17025-accredited materials testing when the need concerns methods covered by this accreditation. Filab laboratory verifies feasibility and the applicable scope before work begins.

Using the results to secure the process

The results are provided as comparative observations and, depending on the selected protocol, images of the surfaces before and after exposure. The differences observed can guide the selection of a formulation, adjustment of a concentration, or implementation of suitable storage conditions.

For applications involving powdered materials, Filab laboratory also offers metal powder characterization services according to ISO 52907.

Have your requirements assessed by Filab laboratory

Filab laboratory combines expertise in materials analysis with the adaptation of test protocols to industrial constraints. Each request is reviewed based on the material, fluid, defects observed, and decision objective in order to propose a proportionate approach.

To move your project forward, you can:

send your affected parts, reference parts, and fluid samples;
specify the machining, rinsing, drying, and storage conditions;
request a feasibility study to define the protocol;
compare your cutting fluid formulations on your metal alloy.

Frequently asked questions

How can you verify that a cutting fluid is compatible with a metal alloy?

Compatibility is assessed by bringing the cutting fluid into contact with specimens representative of the alloy and its surface condition. Filab laboratory adapts the exposure conditions to your application, then examines any occurrence of stains, deposits, pitting, colour changes or other surface alterations.

Which corrosion defects can be investigated on machined parts?

The tests can investigate stains, pitting, generalized oxidation, tarnishing, deposits or localized changes in surface appearance. Analysis of the affected areas helps determine whether the defect is consistent with an interaction between the cutting fluid and the alloy concerned.

Which parameters should be provided to prepare a cutting fluid corrosion test?

It is recommended to provide the alloy grade, surface condition, any treatments, the fluid reference and concentration, application conditions, as well as available affected and reference parts. These elements enable Filab laboratory to develop a protocol consistent with your process.

How can several cutting fluids be compared for the same metal grade?

To compare several fluids, Filab laboratory applies identical conditions to each formulation on specimens representative of the same alloy. The assessment focuses on the appearance of the surfaces and the alterations observed after exposure, in order to identify differences between the solutions tested.

Why entrust cutting fluid corrosion testing to Filab laboratory?

Entrusting these tests to Filab laboratory provides you with a protocol developed around your fluid-material combination and production conditions. The results offer concrete information for investigating a defect, comparing solutions, and guiding your qualification decisions.