Brass heat treatment

Copper-Zinc Alloy : An Introduction

Copper in pure form has found its significant use only in electrical applications . But with the continued study of copper , the addition of other metals called alloys was developed which enhanced its various properties . Now , different Copper-based alloys were widely used in different aspects of engineering and manufacturing . One of the best known and is widely used is the Copper-Zinc Alloy or Brass (De Garmo Black , Kohser , 1997 ) Brasses according to Yu Lakhtin (1979 ) are binary and multiple-component alloys based on copper with which the main component

is zinc ' Below is the phase diagram of Copper-Zinc Alloy at different Cu-Zi percentage and temperature

Figure 1 . The Copper-Zinc Phase Diagram ? and ' phases . At these two different phases , different characteristics were distinct . Their distinction according to Lukhtin (1979 ) depended on Zinc content from 48 to 50 . The single-phase or ?-brasses were characterized by Lukhtin (1979 ) as can be readily worked in both the hot and cold conditions ' while the two-phase brasses are hot-worked at temperatures corresponding to the regions of the ' or ' phases ' He also described ' brasses as having higher strength and wear resistance but less ductility . According to him , ' brasses were often alloyed with Al , Fe , Ni , Sn , Mn , Pb and other elements ' And the addition of these alloying elements , except Ni , reduces Zi solubility in Cu and promotes the formation of ?-phase Further he wrote , the addition of alloying elements , except Lead raised the strength and hardness of brass but reduced its ductility Lead improved the machinability and antrification properties of brasses

According to De Garmo , et .al , Copper-based alloys are commonly identified through a system of numbers standardized by the Copper Development Association (CDA ) which was adopted later by the American Society for Testing and Materials (ASTM , Society of Automotive Engineers (SAE , and the US government

Brasses were classified into wrought and casting brasses . According to Lakhtin (1979 , wrought brasses are used to make sheets , band stock tubing , wire and other semi-fabricated products and casting brasses for making foundry castings

Owen Ellis (1948 ) further classified Brasses casting alloys into Red Brass , Leaded Red Brass , Semi-Red Brass , Leaded Semi-Red Brass , Yellow Brass , Leaded Yellow Brass , High-Strength Yellow Brass (Manganese Bronze , Leaded High-Strength Yellow Brass (Leaded Manganese Bronze Silicon Brass , Tin Brass , Tin-Nickel Brass , Nickel Brass (Nickel Silver and Leaded Nickel Brass (Leaded Nickel Silver . In his classification Red Brasses consisted 2 -8 zinc , less 0 .5 lead , and with tin less than the zinc the same amount consisted the Leaded Red Brass except that lead is over 0 .5 Semi-Red Brass consisted 8 -17 zinc , less than 6 tin , and less than 0 .5 lead the same amount consisted the Leaded Semi-Red Brass except that lead is over 0 .5 Yellow Brass consisted over 17 zinc , less than 6 tin , under 2 nickel , iron , or silicon , and with less than 0 .5 lead the same constitutes for Leaded Yellow Brass except for lead which is over 0 .5 High-Strength Yellow Brass consisted of over 17...