Materials science

LOW TEMPERATURE TOOL STEELS
This group includes all tool steels and alloying steels that differ little from carbon steels in terms of toughness.
a + b -brass microstructure. The boundary between single-phase α-brass and two-phase α + β brasses is 39% zinc.


9 - laboratory work
Non-ferrous metals and alloys
studying microstructures


The purpose of the work: to study the structures of non-ferrous metals and their alloys used in technology, to determine the connection between their structures, properties and areas of use.


Theoretical information
Non-ferrous metals have some unique properties. For example, the electrical conductivity of copper is high (the relative electrical resistance is 1.7·10 ^-6 ohm · cm), while the density of aluminum and magnesium is very low (Al-2.7 g / cm ³ , M g-1.74 g / cm ³ ), tin, lead and zinc are easily liquefied (Sn-232 ⁰ C, Pb-327 ⁰ C, Zn–419 ⁰ C), ...
Non-ferrous metals are widely used in industry and engineering in the form of various alloys (Tables 6, 7, 8 and 9).
MOO (99.99% copper), MO (99.95% copper), M I (99.9% copper), M 2 (99.7% copper ), M 3 (99 .5% copper) and M 4 (99.0% copper) brands are produced.
MI brand copper contains up to 0.1% additives, it is used as wires, cables and other items in machine building due to its very high conductivity.
Figure 16.1 shows the microstructure of copper softened by deformation (rolling). In the structure, there are large copper grains with dark rings, and traces of deformation are visible in the form of double displacement lines.

Figure 16.1. Microstructure of deformed and then annealed copper. The metal was treated with a solution of ferric chloride in hydrochloric acid, x200.

An alloy of copper and zinc is called brass . The structures and properties of brasses depend on the amount of zinc in their composition.

Because L68 brass (32% zinc, 68% copper) has high plasticity and corrosion resistance, products (wires, sheets, pipes,...) are made from it by rolling and stamping. Figure 17.2 shows the microstructure of deformed and softened single-phase L68 brass. Dark streaks are also visible on it. - phase - a solid solution of zinc in copper (plastic structure).

Figure 16.2. Microstructure of L 68 brass as deformed and then annealed . The metal was treated with a solution of ferric chloride in hydrochloric acid, x100