Brass L63: overview, properties, specifications and features

2024 Author: Howard Calhoun | [email protected]. Last modified: 2024-01-02 13:48

Many people have often noticed shiny handles on interior doors, golden chandeliers or candlesticks. All these elements are made of an alloy called brass. In this article, we will take a closer look at its properties and characteristics, paying special attention to the L63 brand.

What is brass?

Brass is one of two known copper alloys (the other is bronze). Its basis is copper, in which different amounts of zinc are dissolved. As is known, copper has a face-centered cubic crystal lattice (fcc). In turn, pure zinc forms a hexagonal close-packed structure (hcp). Both lattices are incompatible, therefore, in the case of equal atomic concentrations of zinc and copper, so-called double brasses can form. They are characterized by the simultaneous existence of two phases (fcc and hcp solid solutions).

If you pay attention to the table of D. I. Mendeleev, you will notice that zinc in it is at number 30, and copper is at number 29.have similar atomic radii. This fact allows, despite different crystal lattices, to form single-phase solid solutions when the copper content in the alloy exceeds 13.5%, as can be seen from the presented Zn-Cu phase diagram.

Thus, if copper is the main component, then under equilibrium conditions there is only one phase - a solid solution of zinc in fcc copper.

Brass brand L63

This is one of the most common alloys cast in our country. It is not difficult to understand what the letter and numbers in the brand name mean: "L" is actually brass, the number 63 indicates the percentage of the main component, that is, copper. In fact, the reality may differ slightly from the indicated figure. So, in the composition of brass L63, the amount of copper ranges from 62% to 65%, and zinc in the alloy contains from 34.2% to 37.5%.

Almost all brass are well machined at low (room) temperatures. The brand in question is no exception. Due to its excellent mechanical properties, it is used to produce a wide range of parts, including thin sheets, pipes and rods of various thicknesses.

It should also be mentioned that the product of the brand in question is easily polished, so many jewelry made from it have a golden color and a brilliant hue.

One of the important advantages of brass L63 is its relative cheapness compared to other alloys containingmore copper.

Characteristics L63

As you know, pure copper is a fairly soft material. Its shear strength is 210 MPa. The replacement of one third of the copper atoms in the fcc lattice with zinc atoms, as well as a certain heat treatment of brass, lead to an increase in its mechanical shear strength up to 240 MPa.

Another advantage of the characteristics of L63 brass over the properties of copper is its higher hardness while maintaining ductility. Note that in the case of incorrect processing, for example, insufficient annealing, second phases based on zinc may appear in the product of the grade under consideration. Two-phase brass leads to a significant deterioration in mechanical and technological properties. In particular, the alloy becomes brittle and almost loses its ductility.

The difference between brass and other metals is the absence of sparking during mechanical shocks. This property allows the use of L63 in the production of containers for the storage and transportation of flammable substances.

If we talk about the disadvantages of this grade compared to pure copper, we should mention a slight decrease in toughness. In addition, L63 brass is a poor conductor of electricity and heat.

Specific Gravity of Alloy

Recall that density is a value equal to the ratio of the mass of a body to the volume it occupies in space. Density is calculated using the following formula:

ρ=m/V.

In the case of multicomponent alloys in whichsimple mixing of chemical elements with a low enthalpy of formation, you can use the following formula to determine their density:

ρ=∑_im_i/∑_i(m _i/ρ_i).

Where m_i and ρ_{i are the mass and density of the i-th component in the mixture.}

Using the written formula, you can calculate the specific gravity of brass L63. If the expression for ρ is written for two components, then we get the following equality:

ρ=ρ_znρ_cu/(ρ_zn+ x(ρ_cu-ρ_zn)), where x=m_zn/(m _zn+m_cu).

The x parameter reflects the mass fraction of zinc in the alloy. Since the masses of the atoms of the brass components are close, we can assume that the mass fraction is equal to the atomic fraction. If, for example, we take the composition of 63% Cu and 37% Zn and take into account that ρ_cu=8960 kg/m³and ρ _zn=7140 kg/m³, then we get the value ρ=8188 kg/m^3.

Turning to the experimental value of the density of brass L63, we see that it corresponds to 8440 kg/m3 at room temperature. The discrepancy with the theoretical result is due to two main factors:

• during the formation of an alloy, there is some negative enthalpy of mixing of the components;
• it contains impurities of heavier metals.

Heat treatment features and corrosion resistance

Product in questionmelts at 906^oC. In the range from 750^oC to 880^oC, it still exhibits good plasticity, so it can be machined. An important stage in the production of alloy L63 is annealing, which is performed in the range of 550-650^{oC. As a result of this processing, two main processes occur:}

• mechanical stresses are removed;
• dissolve metastable phases to form a single-phase structure.

The presence of mechanical stresses is extremely undesirable for L63. It is known that the addition of zinc to copper leads to a significant improvement in its corrosion resistance, so all brass are quite chemically passive alloys. They are destroyed over time only in aggressive environments, such as perchloric and nitric acids. However, the presence of stresses in brass structures significantly impairs their corrosion resistance.

Because of the aforementioned stresses, fast cutting is not recommended for L63 products.

Applications

The considered brand of brass is widely used for the manufacture of tapes, rods, sheets and pipes. The alloy is also used to make wire, which is used for rivets.

Summarizing, it should be said that L63 is used wherever it is necessary to carry out significant cold deformations in the production of parts. Couplings, tanks and various decorative elements are made from it.