Brass grade L63: decoding, characteristics of the alloy, GOST

Decoding the alloy grade and its characteristics

The interpretation of L63 is as follows: L indicates brass, and the numbers indicate the presence of 62-65% copper in the composition. Single-phase structure promotes ease of processing. The production of brass L63 is regulated by GOST 15527-2004; it is used not only for practical but also for decorative purposes.

Among the key characteristics of L63 brass alloys is increased corrosion resistance compared to copper. The material exhibits these qualities:

• in the marine environment;
• in alcohol solutions;
• in fresh water;
• among halogen gases.

The material has good casting characteristics. Suitable for gas and electric welding. Melts at a temperature of 906 °C. During the melting process, components harmful to the human body are formed, so the procedure is carried out in ventilated rooms. The zinc present in the composition is flammable. The wear resistance is increased by hot firing.

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Casting brass alloys

There are two main types of brass alloys for mass consumption: casting and wrought (jewelry is also included in a separate group). The characteristics and processing technologies of casting brasses are described in GOST 17711. Materials of this type are characterized by increased density, reduced gas content and good corrosion resistance. Due to the partial evaporation of zinc during the casting process, the metal is well deoxidized, but it is important to control this process so that the characteristics of the finished product correspond to the calculated values.

Cast brasses are characterized by reduced segregation (heterogeneity that occurs during the casting and crystallization process), increased melt fluidity and a low shrinkage coefficient. In terms of mechanical characteristics, finished parts made from this metal are similar to products made from aluminum and tin bronze, while their cost is significantly lower due to a simpler production technology.

Of course, cast brass alloys also have certain disadvantages. Thus, during crystallization, quite large cavities can form on the surface of products, leading to a significant percentage of defects. It is also important to consider that due to the evaporation of zinc, smelting must be carried out using special fluxes.

Phase state of matter in alloy L63

Alloys are single-phase and two-phase. Two-component alloys, including L63, mainly belong to single-phase structures. When the second phase appears, the mechanical properties of products decrease: fragility and hardness increase, and the ductility of products decreases. For this reason, two-phase a+b brasses are difficult to work with pressure. Single-phase alloys are as well processed by pressure as they are cast into ingots. L63 - contains a small amount of substance in the b-phase, therefore it lends itself well to pressure processing: rolling, deep drawing, embossing, drawing, bending without serious consequences, subject to the processing regime.

This alloy is used to produce:

• Tape L63
• Plate L63
• Pipe L63
• Wire L63
• Circle L63
• Sheet L63
• Rod L63

According to GOST 15527, L63A blanks with antimagnetic properties are also produced. The alloy is suitable for casting, but has limitations in cutting and machining.

Application

L63 is most effectively used in the production of parts made by deformation, with high requirements for corrosion resistance. It is used to produce boiler pipes, tanks, radiator tapes, electrodes, solder wire, couplings and rivets, decorative elements in design and architecture and other products.

L63 is suitable for casting and machining. Under the same conditions, it exhibits greater strength compared to LS59-1, in the presence of cuts, on products under load, although it is inferior to the latter in terms of machinability by cutting.

Physical and mechanical properties

Alloy L63 is double, the structure is single-phase. Compared to copper, it has higher strength, hardness, ductility, elasticity and corrosion resistance. With increasing zinc content, these indicators increase. The greatest practical value for the crystallization of alloys based on copper and zinc are compounds with a zinc content of up to 50%. This number includes brass L63.

Structure

According to the Cu-Zn phase diagram, depending on the composition (zinc content from 0 to 39%), the material is a single-phase brass consisting of an a-solid solution with an equilibrium structure. This amount of zinc allows the alloy to crystallize in an equilibrium state, forming a face-centered cubic lattice (FCC), which achieves its plastic state. An increase in the zinc content in single-phase brasses is accompanied by an increase in their strength and ductility.

Plastic

The relative elongation of the material in the cold state, which characterizes its plasticity, is 55%. In the annealed state, L63 brass is the least ductile. But in the stage of applying cold deformation, plasticity persists for a long period. Higher plastic characteristics of the alloy are noticed when using soft stress state schemes during the deformation of the material, which is taken into account when predicting the possible destruction of the metal.

Susceptibility to processing

L63 is a single-phase alloy, in the b phase, which reduces the mechanical properties of products, contains a negligible amount of substance, and therefore lends itself well to pressure processing at low temperatures:

• minting;
• rolling;
• bending;
• deep drawing;
• drawing

The processed material requires strict adherence to the cooling regime.

Some alloy parameters

Compared to copper, the thermal conductivity and electrical conductivity of L63 brass due to the high zinc content is lower, and the workability is 2 times higher. The impact strength of the alloy is worse than that of L68, but better than that of multi-component brass.

Characteristics of brass L63:

• electrical resistivity – 0.065;
• impact strength – 14;
• machinability – 40%;
• thermal conductivity – 0.25.

Specific gravity of brass l63 - 8.44 g/cm

3

. The coefficient of friction with lubrication is 0.012, without lubrication - 0.390. Fluid flow - 65 cm, linear shrinkage - 1.77%. Brinnell hardness – 150-160 MPa.

Strength

Alloy L63 has the greatest strength in the cold state. The shear strength is 240 MPa. According to this indicator, the metal is inferior to brass L59-1. The tensile strength (ultimate strength) of double brass L63 in the state of extreme hardening is 735 MPa. The tensile strength of a hard alloy for rolling is in the range of 680-750 MPa, for a soft alloy - 380-450 MPa.

Melting temperature

The temperature range for thermomechanical and heat treatment of this metal is less than for other double brasses. The melting point of brass L63 is 906°C.

Due to the fact that with an increase in the zinc content in the brass alloy, the melting temperature decreases, in order to avoid burnout of the workpieces and their overheating, the temperature of hot processing is reduced to 750-880, and annealing - to 550-660°C.

At the same hot deformation temperature, brass L63 has the lowest values ​​of deformation resistance. The conditional yield strength of the alloy is 700 MPa.

Temperature conditions for processing double brass grade 63:

• casting – 1060-1100°C;
• hot deformation – 650-850;
• beginning of recrystallization – 350-370
  ;
• complete annealing – 660-670°C.

Corrosion resistance

Brass grade L63 in a cold state is subject to corrosion (seasonal) cracking and dezincification (dissolution in an aqueous environment). After the brass dissolves, due to an exchange reaction, copper precipitates from the solution. The copper film has a spongy appearance and creates a galvanic couple with brass, which accelerates the corrosion process. Dezincification occurs more intensively with increasing temperature of the environment and increasing the speed of water movement.

Causes

The main reasons leading to corrosion cracking of alloy L63:

• unfavorable environment (moisture and oxygen content, traces of ammonia, mercury salts, sulfur dioxide);
• the presence of residual tensile stresses in the metal;

Seasonal phenomena (autumn, spring), when air humidity and, accordingly, the ammonia content in it are increased, are considered especially unfavorable in terms of corrosion.

Internal residual stresses in the workpiece are divided into:

• the first kind (zonal), which are caused by the uneven distribution of deformations during pressure treatment of the material and uneven cooling of the workpiece after heat treatment;
• of the second kind, the causes of which are phase and structural transformations in the alloy.

Anti-cracking measures

To avoid corrosion cracking, use:

• low-temperature annealing of brass to reduce residual stress at 240-300°C;
• creation of compressive residual stresses in the outer layers of the workpieces;

carrying out other production activities aimed at reducing the limit of residual tensile stresses in the metal.

Resistance and instability to corrosion

L63 has increased anti-corrosion resistance in the following conditions:

• air environment;
• dry steam;
• fresh and sedentary sea water;
• dry halogen gas;
• alcohol, freon, antifreeze.

After processing on machines or by cutting, the L63 material loses its resistance to corrosion due to disruption of the crystal structure.

The instability of the alloy to corrosion cracking is observed upon contact:

• with mine waters;
• hydrogen sulfide;
• high pressure;
• fatty acids;
• wet saturated steam;
• oxidizing solutions;
• mineral acids;
• chlorides.

Thin-walled products are most susceptible to corrosion. It is not recommended to use L63 alloy in contact with zinc, aluminum and iron to avoid its accelerated destruction.

What is brass?

Brass is one of two known copper alloys (the other being bronze). Its base is copper, in which varying 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, so in the case of equal atomic concentrations of zinc and copper, so-called double brasses can be formed. 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 at number 29. Such closeness of the positions of the elements in the periodic table indicates that they have close atomic radii. This fact makes it possible, 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.

Structure and possible processing methods

The mechanical characteristics of brass of the brand in question, like any other material, are determined by the phase state of its internal structure. In the structure of L63 brass there is no second so-called b-phase, which, if present in a copper alloy, makes it harder and more brittle and significantly impairs the ductility of the base metal. It is the single-phase structure of the alloy of this brand that explains the fact that products made from it are perfectly amenable to pressure processing using almost any of the technologies used today (rolling, drawing, drawing, embossing, bending).

Structure of brass: single-phase (a) and two-phase (b)

Casting methods and cutting technologies are also used to manufacture products from L63 brass, which significantly expands the scope of its application. At industrial enterprises engaged in the production of metals, brass grade L63 is produced in the following form:

• rolled sheets, strips and plates;
• rods with different cross-sectional shapes;
• pipe products;
• wire.

Guaranteed mechanical properties of L63 brass sheets in comparison with L59-1 and copper sheets

The entire range of products made from L63 brass is specified by GOST 15527-70 (new edition - GOST 15527-2004). In addition, as GOST 15527-70 prescribes, manufacturers can produce blanks from a modification of this alloy (L63A), which are distinguished by antimagnetic properties. This alloy, having similar characteristics to L63 brass (specific gravity, density, etc.), has better fluidity in the molten state, but products made from it are not very well processed by cutting.

Scope of use

Products made from L63 brass are in demand in the aircraft and automotive industries. Rolled products from this grade of metal occupy a leading position in the production of plumbing and engineering structures.

Tapes, pipes, circles, plates, sheets, rods, wires, containers, and couplings are made from alloy L63. It serves as a raw material for the production of electrodes, design elements, rivets, fittings and furniture structures. Advertising and information signs are also made from it. By themselves, they look attractive, and if desired, they can be further decorated with engraving.

What negatively affects the anti-corrosion properties of L63

Sharp processing negatively affects the corrosion resistance of products made from L63 alloy. This happens due to the destruction of the crystalline structure of the material. Cutting also causes a lot of internal stress. Corrosion cracking is often observed on objects made of such material. The reasons for their appearance may be:

• high humidity;
• presence of ammonia in the operating environment;
• heat;
• wet vapors;
• high pressure

To protect against cracking, products are annealed at low temperatures. Corrosion resistance is also affected by contact with mineral acids, mine waters, chlorides, and hydrogen sulfide. Most often, cracking is observed on materials made of thin sheets. For example, on thin-walled pipes and containers. But under conditions of proper use, such products can last a good period.

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Melt brass technology

To obtain the melt, two main technologies are used:

• melting in crucibles made of refractory clay by heating in a flame or shaft furnace;
• melting in a reverberatory furnace without the use of crucibles.

Molten metal is poured into sand molds to produce blanks and ingots. It is important to consider that part of the zinc evaporates during the process, so it is necessary to choose an alloy in which its proportion will be slightly higher. The correction for evaporation is calculated individually for a specific technology so that the proportions of metals in the finished product correspond as much as possible to the design values.

Standards

Melting point of brass l – Metalist's Handbook

L63 brass is a two-component simple alloy consisting of 62-65% copper, 34.22-37.5% zinc and up to 0.5% impurities. The following impurities may be present in the alloy: iron, phosphorus, tin, and lead. This is one of the most common brass alloys. You can buy brass on our website.

Description of the properties of the processed alloy (L63)

This section discusses the mechanical, physical and technological properties and chemical composition of L63 brass, which is used for cold deformation by deep drawing, drawing, rolling, embossing, bending; for the manufacture of cryogenic equipment products; suitable for soldering and welding; polishes well.

Mechanical properties at T=20 °C of the L63 material are given in table. 6

Table 6.

The physical properties of the L63 material are given in table. 7.

Table 7.

The friction coefficient of the L63 material is given in Table 8.

Table 8.

The foundry and technological properties of the L63 material are given in Table 9.

fTable 9.

The chemical composition in % of the L63 material is given in table. 10.

Table 10.

Note: Zn is the base; percentage of Zn is given approximately

Mechanical properties:

Physical properties:

fWeldability:

Copper and zinc form, in addition to the main b - solution, a number of phases of the electronic type c, d, f. Most often, the structure of brass consists of b - or b + c - phases: b - phase - a solid solution of zinc in copper with a fcc crystal lattice of copper, a c - phase - ordered solid solution based on the chemical compound CuZn with a 3/2 electronic connection with the bcc lattice (Fig. 1)

At high temperatures, the b-phase has a disordered arrangement of atoms and a wide range of homogeneity. In this state, the β-phase is plastic. At temperatures below 454–468 °C, the arrangement of copper and zinc atoms in this phase becomes ordered, and it is designated c. The b phase, in contrast to the b-phase, is harder and more brittle; d - the phase is an electronic compound Cu5Zn8.

Mechanical characteristics

Features of heat treatment and corrosion resistance

The product in question melts at a temperature of 906oC. In the range from 750oC to 880oC it still exhibits good ductility and can therefore be machined. An important stage in the production of alloy L63 is annealing, which is performed in the range of 550-650oC. As a result of this processing, two main processes occur:

• mechanical stress is relieved;
• metastable phases dissolve to form a single-phase structure.

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

Due to the formation of the above-mentioned stresses, it is not recommended to subject L63 products to rapid cutting.

Alloy specific gravity

Let us recall that density is a quantity 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 which there is a simple mixing of chemical elements with a low enthalpy of formation, the following formula can be used to determine their density:

ρ = ∑imi/∑i(mi/ρi).

Where mi and ρi are the mass and density of the i-th component in the mixture.

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

ρ = ρzn*ρcu/(ρzn + x*(ρcu-ρzn)), where x = mzn/(mzn+mcu).

The x parameter reflects the mass fraction of zinc in the alloy. Since the atomic masses of the brass components are close, we can assume that the mass fraction is equal to the atomic one. If, for example, we take a composition of 63% Cu and 37% Zn and take into account that ρcu = 8960 kg/m3 and ρzn = 7140 kg/m3, then we obtain the value ρ = 8188 kg/m3.

Turning to the experimental value of the density of L63 brass, 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.

Anti-corrosion characteristics

All brass alloys (and therefore L63 brass) have high corrosion resistance. They are also distinguished by lower thermal and electrical conductivity when compared with the base metal - copper. Alloy L63 exhibits its corrosion resistance best under the following conditions:

• when in an air environment, including one saturated with salt vapor (sea air);
• when operating products in fresh water;
• when in sea water with low mobility;
• in an environment containing a large amount of halogen gases;
• when exposed to steam whose humidity is low;
• in a liquid medium consisting of antifreeze, freon and alcohol solutions.

Technological characteristics of brass L63

The corrosion resistance of those L63 brass products that have been pre-processed by cutting is significantly reduced. This is explained by the fact that when performing such processing, the crystal structure of the alloy is disrupted, and significant internal stresses are also formed. Corrosion cracking may occur on the surface of products made from L63 brass, the main causes of which are:

• excess humidity;
• high ambient temperature;
• the presence of sulfur dioxide and ammonia vapors in the environment in which the product is operated.

To avoid such a phenomenon, which leads not only to a deterioration in the decorative properties of the product, but also to a decrease in its performance characteristics, experts recommend that parts made of L63 brass be subjected to preliminary annealing, performed at low temperatures.

Regardless of the brand, factors that significantly reduce the corrosion resistance of brass are:

• contact with fatty acids;
• finding the product in so-called mine waters;
• interaction with hydrogen sulfide;
• exposure of the product to high pressure and saturated wet steam;
• interaction with oxidizing solutions and chlorides;
• contact with acids of mineral origin.

Corrosion rate of brass in various environments

Of all the products for the production of which L63 brass is used, those made from thin-sheet material are most susceptible to oxidative corrosion processes. This, in particular, includes tanks and tanks for various purposes, which are widely in demand in almost all industries.

Ways to improve the characteristics of brass alloys

The fragility of the alloy can be significantly reduced by annealing, carried out in the temperature range of 240-260 °C. During heat treatment, the strength properties of the material are improved and residual stress is eliminated. The main way to influence performance characteristics (strength, density, ductility, color, etc.) is the introduction of alloying components.

A pure alloy of zinc and copper is called two-component; if alloying elements are present in the composition, it is called multi-component. The most common alloying additives are lead, silicon, nickel, iron, tin and manganese. Their percentage is usually small (up to 1-1.5%), but the characteristics change dramatically. If you exceed the norm, the quality of brass metal products can significantly deteriorate.

The introduction of silicon and lead makes it possible to improve the strength and antifriction characteristics of brass, due to which the wear resistance of mechanical parts made from it significantly increases. If the mass fraction of silicon exceeds technical standards, the characteristics of brass may deteriorate sharply. Also, lead and silicon, when proportioned, can improve the aesthetic properties of the material.

Tin, aluminum and manganese increase tensile adaptability, and the addition of iron and manganese increases the elongation rate. It is important to note here that all other alloying additives have a negative effect on the elongation index.

To increase the anti-corrosion properties, nickel, tin, manganese and aluminum are added to brass alloys. The addition of nickel helps prevent cracking in high humidity conditions. An additional positive effect of tin alloying is to increase strength, density and resistance to sea water and salt spray. Therefore, such materials are used in devices intended for shipping.

Alloying with lead increases ductility and manufacturability, making brass easier to machine cut. When processed on a lathe, the workpieces do not crack. The chips are small and the surface is almost perfectly smooth, so the finished part does not require finishing.

Arsenic is rarely used as an alloying component for zinc and copper alloys. Typically, parts alloyed with it are used to work in aggressive chemical environments. If iron and nickel are added to the alloy simultaneously with arsenic, the durability of the finished product increases significantly, and it can work in contact with weak solutions of alkalis and acids.

Rolled metal

Pipes in accordance with GOST 494 from LS59-1 are produced by pressing. In addition, a wide range of products from this material are produced in accordance with GOST. Since the alloy has low mechanical properties for pressure processing, although it is generally considered pressure-processable, pipes are made from it using continuous casting methods. And their cost is much lower than pressed ones.

Cold-deformed general-purpose wire is produced in accordance with GOST 1066, and has a square, round or hexagonal cross-section.

Cold-worked sheets LS59-1 have high hardness and wear resistance, and, as mentioned above, are used in machine tool construction. This is one of the most popular types of rolled brass sheets. In addition, sheets are produced from LS59-1 in soft, semi-hard, and hard states.

LS59-1 bars of hexagonal and square shape have found the greatest use. This is a very inexpensive type of rolled product that is easy to cut, and in addition, it has strong ribs. Thanks to this, at minimal cost it is possible to produce all kinds of small and large parts with good anti-friction properties from rods. This alloy is used to produce drawn and pressed rods in hard, soft or semi-hard states.

Semi-finished products from brass L63. Application

L63, as mentioned earlier, is most widely used in all areas of industry.

Wire from this alloy is available in soft, semi-hard and hard states. It is used for the manufacture of rivets, due to the good ductility of this material, it is used as solder, and electrodes for electroerosive machines are produced from high-precision wire.

L63 pipes come in cold-deformed or pressed form and are widely used everywhere, in particular as pipes for boilers.

A wide range of sheet metal products is produced from L63 alloy. The alloy has high ductility and strength compared to Cu. But the best performance in this regard is given by the L68 alloy.

L63 rods are supplied in bulk, in solid, semi-solid, solid state, or pressed, with a diameter from 3 to 180 mm. Among other two-component brasses, this alloy stands out for its highest shear strength, high resistivity and excellent machinability. In terms of impact strength, L63 is inferior to alloys with 68% copper content, but is significantly superior to multicomponent alloys. In terms of shear strength, L63 is inferior to L59-1. The thermal and electrical conductivity of the alloy with 63% Cu is relatively low.

Corrosion resistance of material LS59-1

After processing brass blanks LS59-1

, the material does not experience strong stress, lead forms a separate phase, for this reason, it is more resistant to seasonal cracking, which manifests itself with increasing humidity and ambient temperature, in which it is superior to L68 and L63.

In general, our multi-component alloy is resistant to corrosion, under the same conditions as most brasses. It should not be used in contact with Fe, Al, Zn. He also shows himself poorly:

• in air saturated with moist vapors, at high pressure,

• in contact with fatty acids,

• in hydrogen sulfide,

• mine waters,

• mineral acids,

• as well as in oxidized solutions,

• and with chlorides.

Resistance to corrosion is manifested by:

• in air and maritime climates,

• in dry vapors,

• fresh waters,

• freons, alcohols, antifreezes,

• salty sea water in a sedentary state.

And the presence of excess oxygen, ammonia or carbon dioxide in vapor or water negatively affects the corrosion resistance of this material.

Manufacturability of brass

Copper- and zinc-based metals lend themselves well to machining, making it possible to turn any parts from blanks and preliminary castings. In addition, they lend themselves well to soldering.

The main disadvantage is the tendency for brass with a high zinc content (more than 20%) to crack, especially when used in a humid environment and in the presence of ammonia vapor. The first sign of a decrease in the strength of rolled brass metal is the loss of natural color; other properties gradually deteriorate.

Chemical composition of L63 alloy used for the production of brass pipes

A popular material for brass pipes is L63 alloy, which in its chemical composition must meet the requirements of GOST 15527-2004. L63 brass is a two-component alloy containing from 62 to 65 percent copper and 43.22 to 37.5 percent zinc. A feature of the copper-zinc alloy of this category is that a significant part of the copper is replaced by zinc, which helps reduce the cost of products with high performance characteristics. Many consumers of brass alloy L63 also highlight the quality of its aesthetic appearance, which allows it to be used not only for the manufacture of products used in industry (brass pipes, wire, rods, etc.), but also for decorative products.

Main characteristics

Marking l63 means:

• L - brass;
• 63 is the mass percentage of copper content in this alloy.

Foreign analogues

International marking (exact and closest analogues) of brass L63:

• C27400 - USA;
• C2720 - Japan;
• CuZn37 - Sweden, Austria, Poland;
• CZ108 - England;
• P-CuZn37, P-OT63 - Italy;
• 2.0321CuZn37 - Germany;
• U-Z36, CuZn36 –— France;
• CW507L, CuZn36 - European Union;
• 423213 - Czech Republic.

Chemical composition

According to Interstate Standard 15527-70, brass grade L63 (according to ST SEV 379-76 - CuZn37) belongs to copper-zinc alloys processed by pressure and is simple (double) brass. In accordance with this GOST, material L63 has the following chemical composition:

• copper - 62-65%;
• lead - 0.07%;
• iron - 0.2%;
• antimony - 0.005%;
• bismuth - 0.002%;
• phosphorus - 0.01%.

Total other impurities contain 0.5%. The share of the main alloying component - zinc - accounts for from 37.5 to 34.5%.

The approximate calculated density of brass L63 is 8.5 g/cm.

In materials used in the food industry, the mass fraction of lead should not exceed 0.05%.

The physical and mechanical properties of L63 brass are established by standards for a particular type of product or are specified in an agreement between the manufacturer and the consumer.