Material defects dents

Dents in tubing can induce erosion failures, especially in soft metals such as copper and brass. Welding and improper heat treatment of stainless steel can lead to localized corrosion or cracking through a change in the microstructure, such as sensitization. Another form of defect is the inadvertent substitution of an improper material. 

FIGURE 15.1 Two-dimensional illustration of crystalline order, (a) Example of a crystal lattice with perfect order, (b) Example of a defect in the crystal leading to a dislocation in the lattice, (c) A polycrystalline material. (From L. S. Dent Glasser. Crystallography and Its Applications. Van Nostrand Reinhold, Wokingham (Berks), 1977.)... 

Schepers E.J.G, Ducheyne P Barbier L., and Schepers S. 1993. Bioactive glass particles of narrow size range A new material for the repair of bone defects. Impl. Dent. 2 151-156. 

One method of feeding material into an entry loop is by simply driving the payoff mandrel with an electric motor (see Fig. 11). Normally, this is accomplished with a DC motor, but on slow speed lines, an AC motor with an on-off -type operation may be adequate. When a DC motor is utilized, the loop position is usually automatically controlled with a set of photocells and flood lights or an ultrasonic sensor. This method of paying off material from the master coil is quite acceptable provided there are no stickers from the annealing furnace or any dents or damage to the sides of the coil. These defects would cause the material to stick to itself and not pay off with the force of gravity as it is uncoiled. 

---