MCrAlY bend test
12-01-2015, 07:36 AM,
MCrAlY bend test
Hi guys,
I have a quality control problem.
I have sprayed MCrAlY (Amdry 365-1) for a customer and he made bend test to check adhesion strength, but the coating cracks and spalls off and he won't accept it.
I know that MCrAlYs coating are brittle before heat treatment and I was wondering if there is any standard or documents to show that this test is not the right one for adhesion before heat treatment.
Any help and info is appreciated.

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12-01-2015, 05:56 PM,
RE: MCrAlY bend test
Bend tests are usually done on thin coatings. Of course a thick coating like you showed is going to crack and spall. A coating is not as strong as the substrate, so it will not handle stresses like cast metal coupons.

Bond strength testing is done according to ASTM C 633-1, and it produces a quantifiable result. It measures the adhesion of the coating to the substrate. A bend test does not produce a quantifiable measurement. In my opinion, it is more of an evaluation of the cohesion of the particles to each other.

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