Possibility of hot cracks formation in welded seam is determined by next factors:
1) Size and character of plastic deformations, formed in metal of welded seam during crystallization;
2) The speed (rate) of increasing these deformations;
3) Deformational capacity of welded seam metal in temperature range of hot Continue reading →
According to AWS A3.0 document the porosity is determined as “continuity transgression in the form of hollow space, formed by captured gas in consolidation process”. Thus we have a right to examine pores as certain hollow spaces or gas pockets inside consolidated metal of welded joint. Thanks to characteristic spherical form the pores are considered to be the least dangerous continuity Continue reading →
For each material, tested for tensile tests, this curve has constant slope. This slope is called elastic modulus.
Steel elastic modulus (or Young modulus) under conditions of room temperature is equal approximately to 30000000 pound-force/inch square, and in case of aluminum this parameter is 10500000 pound-force/inch square. As a matter of Continue reading →
According to dimensions and influence on metal density are there two categories of cracks (local ruptures): microcracks (their dimensions are comparable to dimensions of crystal lattice parameters; are available almost always in real crystals) and macrocracks which appear in weld joint in the course of welding or use of product (are dangerous defect – reason for structural failure).
For formation of nucleuses of critical size there is not enough energy, exuded during atoms transfer from liquid to crystals. It compensates these energetic consumptions for two thirds, connected with surface energy or for half of energy, released owing to atoms transfer from liquid to crystal phase.
Nucleus critical size is decreasing with increasing of overcooling. The value of Continue reading →
