[Colnago]

I have witnessed (and taken part in) this type of test...during my days at college studying structural engineering....specifically the results are used to produce the (Young's Modulus) Stress/Strain graph.....

As for the hammering action, as you correctly described it as cyclic loading I have to question this hypotesis......the analogy I would make is that what you suggest is hitting a stainless steel ball (for instance) with a feather repeatedly for a long enough period will alter the shape of the ball......cyclic loading is not always compounded....i.e. it does not always build up....therefore cyclic loading of a magnitude below the limit of plastic distortion (not failure) will not cause a body of stainless steel to change shape....think of a the steel part of a car wheel.....it sees huge amounts of cyclic loading throughout its lifetime and it does not change shape.....but, if you look at cyclic loading from another standpoint for instance a hammer gently striking a polished stainless steel surface repetitively of course the polished surface will be replaced with an ever so slightly dented area where the hammer strikes......this is the effect on the pins of your bracelet, it has not bent....but nontheless become deformed from its original shape....the point is that this type of distortion of stainless steel can only happen if the elastic limit of the material is exceeded....where the hammer strikes is a stress concentration point due to the tiny contact area....the weight of the hammer over such a tiny area concentrates the stress to a point high enough to deform that tiny area......cyclic loading like this of course can be compounded.....resulting in what has happened to your bracelet......halting this cyclic loading by wearing the watch a bit tighter would prevent further deformation of the pin/bracelet.......does that all make sense?????....sorry for going on.....