How to Bond Stainless Steel
There are several options to bond stainless steel. Stainless steel or “inox steel” is a steel alloy containing chromium. It does not corrode, rust or stain like normal steel. It normally is quite easy to bond and does not require much in the way of surface preparation, however, mirror-finish stainless steel can have a very low surface energy and prove difficult to bond.
Providing you are not dealing with a mirror finish the following adhesive types bond stainless steel:
Anaerobic adhesives – threadlockers, thread sealants, form in place gaskets and retaining compounds all work well on stainless steel. However, it is important to note that stainless steel is a fairly inactive metal so the anaerobic adhesives will develop strength more slowly than the steel fixture times noted on the data sheets. Special grades which cure faster on stainless include; HM163 retaining compound, HM135 threadlocker and LH150 pipe sealant.
Cyanoacrylate adhesives – all grades bond stainless steel, but special grades for metals will have increased adhesion. Permabond 910 is the original pure methyl cyanoacrylate which was developed for bonding metals.
Structural adhesives like one component heat cure epoxies, two component epoxies, and structural acrylics bond stainless steel – again, providing the surface isn’t super smooth. For highest bond strength, contact Permabond for a specialty stainless steel bonding adhesives.
UV curable adhesives bond well to stainless steel providing the second substrate permits UV light to pass through. Metal to glass grades include; UV610, UV620, UV625, UV670 and UV7141.
Surface preparation and bonding stainless steel
Often stainless steel can be bonded as received. However, it can be degreased with isopropanol, or Permabond Cleaner A to remove contamination. Do not use white spirit, turpentine etc… as these may leave a residue. Ensure solvent is fully evaporated before attempting to bond.
How to bond stainless steel that has a mirror finish?
Roughening the stainless steel surface does improve the adhesion and durability of most adhesives.
However, stainless steel is very hard so abrading the surface with sand paper, scotch brite, or steel wool is not easy.
Automated means of abrading the surface can generate heat which, might cause a surface change decreasing the adhesion of adhesives to the stainless steel.
If treatment is needed to obtain a high strength bond to mirror finish stainless steel sand blasting is recommended to roughen up the surface without generating heat.