Although a relatively recent discovery, nanocrystalline materials are a well studied group of materials which have some specific magnetic applications whilst exhibiting some useful property characteristics also.
Due to a very fine distribution of crystalline grains within the amorphous matrix nanocrystalline alloys display excellent soft magnetic properties.
A fatigue fracture will have two distinct regions; One being smooth or burnished as a result of the rubbing of the bottom and top of the crack. The second is granular, due to the rapid failure of the material.
Striations are thought to be steps in crack propagation, were the distance depends on the stress range. Beachmarks on the other hand may contain thousands of striations.
The control of hydrogen content in steels is an important task of steelmakers because of its generally detrimental effects on processing characteristics and service performance of steel products. Just a few parts per million of hydrogen dissolved in steel can cause hairline cracks (flakes), hydrogen embrittlement, hydrogen blistering and loss of tensile ductility, particularly in large steel castings ingots, blooms and slabs.
Fatigue cracking is one of the primary damage mechanisms of structural components. Fatigue cracking results from cyclic stresses that are below the ultimate tensile stress, or even the yield stress of the material.
The fatigue life of a component can be expressed as the number of loading cycles required to initiate a fatigue crack and to propagate the crack to its critical size.
Generally, the high carbon steels contain from 0.60 to 1.00% C with manganese contents ranging from 0.30 to 0.90%.
The pearlite has a very fine structure, which makes the steel very hard. Unfortunately this also makes the steel quite brittle and much less ductile than mild steel.