. Rame e leghe di base : le proprietà fisiche e meccaniche del rame e sue leghe commerciali in forma battuto. Rame e leghe di rame. 28 Rame e leghe a base di aree spugnoso di rame in forma di strati o i cosiddetti "tappi" sulla superficie interessata. Questo spugnoso di rame è una conseguenza della soluzione di frazioni della lega in media e una rideposizione del rame da spostamento chimico. Arsenico, antimonio e fosforo in piccole percentuali frazionario sono dimostrabilmente efficaci nel reprimere o inibire dezincatura in alpha ottoni. Ottone th
1012 x 2469 px | 17,1 x 41,8 cm | 6,7 x 16,5 inches | 150dpi
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. Copper and copper base alloys : the physical and mechanical properties of copper and its commercial alloys in wrought form. Copper; Copper alloys. 28 Copper and Copper-base Alloys spongy areas of copper in the form of layers or so-called "plugs" on the affected surface. This spongy copper is a consequence of the solution of fractions of the alloy in the media and a redeposition of the copper by chemical displacement. Arsenic, antimony, and phosphorus in small fractional percentages are demonstrably effective in repressing or inhibiting dezincification in the alpha brasses. Brass that contains less than 85 per cent of copper may imder certain conditions fail by stress-corrosion cracking or, as it is more commonly called, "season cracking." Conditions that favor this form of failure are the presence of internal stress or stress gradients produced by cold-working operations followed by exposure to mild atmospheric corrosion. The presence of traces of ammonia in the atmosphere is said to favor this form of corrosion. Season cracking can be effec- tively prevented by relief annealing below the recrystal- lization temperature. A type of failure closely associated with season crack- ing and known as "fire cracking" occurs when sus- ceptible brasses in a stressed condition are suddenly exposed to elevated temperatures. The presence of lead in the brass decreases the resistance to this type of failure by promoting greater inter crystalline weakness. In order to avoid this form of failure it is common practice to bring stressed materials up to the annealing temper- ature gradually rather than precipitantly. In the fabrication of susceptible rod alloys it is com- mon practice to flex or spring the rods prior to annealing, to counteract tensile stresses produced during fabrication, and thus reduce liability to fire cracking. Following is a table of the more important commercial alpha brasses: Most common name Gilding metal Commercial "bronze
