Abstract
The problems on melting, casting, forging, change of mechanical properties due to heat treatments and microstructures of 42 kinds of copper base alloys containing 20 per cent of Fe were investigated, and the following results were obtained.
(1) The fluidity of melts added by Al was good, and sound and smooth surface castings were obtained by pouring then into a Durville type casting mould although dross was liable to be formed on the surface of the melts. On the contrary, melts containing Si but no Al were viscous, and liable to form gas bubbles in the castings, the formation of which was prevented by using CaF2-NaCl flux. In melting alloys containing Si and Al, a small amount of dross and fairly sound ingots were obtained.
(2) The primary crystal rich in Fe of alloys containing Cr was apt to become massy particle, and alloys containing Sn or P have shown the tendency to promote the segregation of the primary Fe-rich phase.
The alloys containing Al and Si, say No. 19 alloy, have shown uniform and fine structures. The simultaneous addition of Al-Mn, Al-Ag or Si-Ag to Cu-Fe alloys does not cause to refine the crystal grains of the alloys.
(3) The forgeability of alloys consisted of only two phases rich in Fe or in Cu was good in general. But alloys containing Sn could not be forged due to the formation of a third constituent.
The forging of Cr-containing alloys was difficult. The formation of forging cracks is considered to be due principally to the segregation of the primary Fe-rich crystal of massy particles.
It is the necessary treatment for Si-containing melt to wash it with fluxes and remove the absorbed gases in order to render forging of the castings easy.
(4) The mechanical properties of the alloys were not improved by heat treatments, except 0.6% Be-1.0% Ni-20% Fe-bal. Cu alloy, in which Ni is the necessary element to give the age-hardening property of the alloy in the existence of Be. The age-hardening of this alloy is considered to be due principally to the solubility change of Cu-rich solid solution forming the matrix of the structure.
