Thread Galling Issues with Stainless Steel Fasteners

Thread Galling Issues with Stainless Steel Fasteners

2 min read

One of the benefits of working with stainless steel is its resistance to corrosion. Unfortunately, some people experience issues with stainless steel fasteners and wonder why their fasteners are breaking or getting nicks like cheap screws from the dollar store. Why isn’t this robust metal holding up?

It’s actually the fact that stainless steel is built to avoid corrosion that makes it more susceptible to thread galling. The varied grades of alloy create an oxidized surface to protect it from corrosion, but when pieces of stainless steel are compressed tightly together – especially if they’re the same grade – it is nearly impossible for the atoms to differentiate themselves from one piece of stainless steel to another, so they fuse and create some of these problems:

  • A bulge forms on one of the two surfaces due to the transfer of atoms. As the friction between the fasteners increases, this bulge grows and damages underlying metal.
  • Threads (either male or female) can tear away from their host piece of stainless steel, completely breaking the fastener or the tool responsible for turning it.
  • Molecular level-problems, which are not visible at all to the naked eye, can cause a bolt’s threads to seize or to twist off completely. Your supplier claims there’s nothing wrong with the product he’s selling you, but you continue to have these annoying instances where molecular-level problems quickly expand into something that can damage an entire machine.

Does any of this sound familiar?

Fortunately, there are ways to avoid stainless steel thread galling on your fasteners:

  • When you install the fasteners, slow down the RPM speed.
  • Coat individual pieces of stainless steel – especially their threads – with a lubricant and keep them well-lubricated as time and use wear on.
  • Use different alloy grades for the different pieces of each fastener. Because the materials will have a different hardness, they’ll be less likely to fuse with one another.

Below is a list of common causes of galling and prevention steps.

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Be sure to explore MISUMI’s vast selection of fasteners here.

About the Author

Carlicia Layosa

Carlicia is the Marketing Automation Manager at MISUMI. She holds a bachelor's degree in Mechanical Engineering and a master's degree in Energy Engineering from the University of Illinois at Chicago. She is a Certified SOLIDWORKS Associate, Marketo Certified Expert, and is passionate about education and training.

6 thoughts on “Thread Galling Issues with Stainless Steel Fasteners

  1. Therefore, stainless steel screws are becoming increasingly relevant. Especially when it comes to applying them to the natural atmospheric conditions where they are exposed to acid rain.

  2. Make one of the mating parts out of an anti-gall stainless alloy, e.g. Nitronic 60. For instance if you need a tapped hole you can use a helicoil in that material, available off-the-shelf. Screws can be obtained in that material, though I haven’t seen them off-the-shelf yet. If you can use anti-seize compound, then by all means use normal stainless alloys. But many applications for stainless items prohibit lubricants. Hey Misumi.. how about adding anti-gall stainless steel screws to your catalog?

  3. Been through this before and he is correct. Dry fitting and tightening bolts with nylon lock stainless – they became fixed/melded. These were brand new and I had just put them on while mounting the outboard. I decided to run my steering cable a little differently and got all three nuts of but the lower right and it snapped. Then later while adjusting and still dry fitting the upper right nut melded. Both of these were moving along fine but then stopped and that was it. 1/2″ 13mm 4″ stainless bolts with 1/2″ stainless nylon locking nuts 304 grade.

  4. It may be a good alternative to try the “v” angled thread files. The angle is 60% degrees so it is similar to the angle on Inch, Metric, Pipe, Male, and Female Threads. The files are basically round and they work great in restoring internal and external threads.

  5. good explanation, thank you !

    I have found the very same problem (and solutions) when assembling aluminum pipe – the threads essentially “weld” together and simply can NOT be disassembled

  6. We have decided to have our threads coated with a dry thread lubricant. It may cost $3-$8 per part, but is much cheaper than scrapping a $30-$100 part.

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