I dont know if anyone else has mentioned ed this, but IF YOUR ROLLERS ARE TRUE AND ACCURATE, the following may help. When you roll metal, any slight variations in speed, or the angle at which the metal is fed into the rolls, or slight variations in thickness or hardness of the sheet can give you waves. All the prior suggestions if others may help, BUT, sometimes it seems unavoidable. However, when you get those waves, something you cannot see also happens. Those waves correspond to slight differences in hardness. As you continue to roll, and the hardness increases, those variances in hardness will tend to make the metal correct itself, with the wave induced stresses from one pass through the mill tending to cancel out the prior wave induced stress/hardness variations. As you continue to roll, you will find a point where the waves have largely disappeared, and other than an overall slight curve that may remain, the metal will be mostly flat again. At this point, the metal hardness will have reached a uniform full hard temper. Dont roll farther than this. Time to anneal. And if your metal is annealed while resting on a flat surface, it may flatten itself even more. Now, this may be of little help if you reach the desired thickness before those internal stresses have evened out, letting the sheet flatten itself out. But that may also offer some guidance in how often, or when, to anneal, and one reason why annealing too often, or not often enough, may give you poorer metal structure. Doing it right encourages the goal of achieving the most uniform structure of the smallest crystal size, a structure which will give you the strongest, most workable metal. Hope that helps.
Peter Rowe
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