Corrosion

Dear friends,

Let’s talk about a subject which plagues everyone, corrosion. A few years back the National Bureau of Standards now called the National Institute of Standards and Technology, did a study and estimated that the annual costs associated with corrosion in the United States was between $9 billion and $90 billion. These figures have been affirmed by various organizations as well as by the National Association of Corrosion Engineers. So as you can see, corrosion is a major problem for us all. In order to understand corrosion, we must first understand what corrosion is. As stated in the Corrosion Engineering Handbook (second addition) on the Fundamentals of Metallic Corrosion, by Philip Schweitzer, “Corrosion is the degradation of a material’s properties or mass over time due to environmental effects”. When a material corrodes it elements are basically returning to their natural state. These elements turn into oxides, sulfides or other basic metallic compounds.

All metals corrode (unless present in an inert atmosphere or vacuum environment), both ferrous and non-ferrous alike. It is not the scope of this article to go in-depth into the various forms of corrosion; however I will list them for your future reference. A more in-depth study of these forms of corrosion can be found in the before mentioned reference.

1.        Pitting
2.        Galvanic corrosion
3.        Uniform corrosion
4.        Stress corrosion cracking
5.        Intergranular corrosion
6.        Crevice corrosion
7.        Biological corrosion
8.        Selective corrosion
9.        Erosion corrosion

Let’s learn about the various forms of corrosion that machine shops and manufacturing companies alike deal with regarding the use of metalworking fluids. These forms of corrosion can comprise the following – Pitting, Galvanic, Biological corrosion and in the aerospace sector, Stress corrosion cracking (SCC). Many factors can induce these forms of corrosion. An example would be the result that a metalworking fluid with an excessively high pH factor would have on Aluminum, such as Pitting and Galvanic Corrosion/Aluminum Staining. Biological corrosion induced by a microorganism’s metabolic activity, can cause corrosion by forming various acids in the bulk metalworking fluid itself, or by attacking the metals surface directly via bio-films. Stress corrosion cracking takes place when various chemicals capable of causing SCC attack the metal surface. An example of a “capable chemical”, in this case Chlorinated Paraffin found in various MWF’s, coming in contact with Titanium can induce Hydrogen Embrittlement. This corrosion takes place when hydrogen forms on the metal surface under heat and pressure, forming a hydride phase, thus allowing hydrogen to enter into the Titanium alloy.  So unless you’re going to live in a vacuum, we’re all going to deal with corrosion at some time in our lives.  Boy! Where are the Rust-eze guys when you need them? J

Stay tuned for more useful coolant related tips, from The Coolant Guy!

Best regards,

Brett Reynolds, CMFS

Brett Reynolds, “The Coolant Guy” works for Blaser Swisslube Inc.

If you would like more useful information regarding metalworking fluids, or would like to find out more information about Blaser metalworking fluid products,

Please contact Brett at 801-722-4095 or via

E-mail at b.reynolds@blaser.com

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