What is bronze?
What is bronze and what material is bronze made of?
Bronze is an alloy.
It is a copper alloy with tin, aluminum, beryllium, silicon, manganese, cadmium, zirconium, titanium, magnesium, iron, etc. as the main alloy elements.
All kinds of copper alloys except pure copper, copper zinc series (brass) and copper nickel series (white copper) can be classified as bronze.
Because some alloy elements are added to bronze, its strength is greatly improved, and at the same time, it has obtained some specific properties.
The compression resistance of bronze becomes larger, although it brings difficulties to processing, its advantages of high elasticity, anti softening, high corrosion resistance, high wear resistance, etc. also make the application field of bronze greatly expanded.
Types of Bronze
How many types of bronze are there?
According to the classification of its main elements, bronze can be divided into tin bronze (including tin phosphorus bronze), aluminum bronze, beryllium bronze, silicon bronze, manganese bronze, chromium bronze, cadmium bronze, zirconium bronze, chromium zirconium bronze, titanium bronze, magnesium bronze, iron bronze, etc.
The copper base alloy with tin as the main alloy element is called tin bronze.
The tin content of tin bronze used in industry is mostly between 3% and 14%.
Tin bronze with tin content less than 5% is suitable for cold working;
Tin bronze with tin content of 5%~7% is suitable for hot working;
Tin bronze containing more than 10% tin is suitable for casting.
Tin bronze is widely used in shipbuilding, chemical industry, machinery, instrument and other industries, mainly for manufacturing wear-resistant parts such as bearings, shaft sleeves, elastic components such as springs, anti-corrosion and antimagnetic parts, etc.
The copper base alloy with aluminum as the main alloy element is called aluminum bronze.
The mechanical properties of aluminum bronze are higher than those of brass and tin bronze.
The aluminum bronze used in practice has an aluminum content of 5%~12%, and the aluminum bronze with an aluminum content of 5%~7% has the best plasticity and is suitable for cold working.
When the aluminum content is greater than 7%~8%, the strength increases, but the plasticity decreases sharply.
Therefore, it is mostly used as cast or after hot working.
The wear resistance and corrosion resistance of aluminum bronze in atmosphere, seawater, seawater carbonic acid and most organic acids are higher than those of brass and tin bronze.
Aluminum bronze can be used to manufacture gear, shaft sleeve, worm gear and other high-strength wear-resistant parts as well as high corrosion resistance elastic elements.
The copper alloy with beryllium as the basic element is called beryllium bronze.
The beryllium content of beryllium bronze is 1.7% ～ 2.5%.
Beryllium bronze has very high elastic limit and fatigue limit, excellent wear resistance and corrosion resistance, good conductivity and thermal conductivity, non magnetism, and no spark when impacted.
Beryllium bronze is mainly used to make important springs of precision instruments, clock gears, bearings and bushings working under high speed and high pressure, as well as welding electrodes, explosion-proof tools, navigation compasses and other important parts.
Bronze with silicon as the main alloy element.
In addition to silicon, silicon bronze used in industry also contains a small amount of manganese, nickel, zinc or other elements.
Silicon is a limited solid solution in copper, and the maximum solubility can reach 5.3% at 852 ℃, which decreases with the decrease of temperature.
However, the aging hardening effect is not strong, and generally no strengthening heat treatment is carried out.
The silicon content of deformed silicon bronze is 1%~4%.
With the increase of silicon, brittle phase will appear and plasticity will be reduced.
Silicon bronze has a small crystallization temperature range, sufficient fluidity, and higher mechanical properties than tin bronze.
It can be used as a substitute for tin bronze in the machinery manufacturing industry.
Manganese bronze is an alloy with copper as the base element and manganese as the main alloy element.
The main grades of manganese bronze are QMn1.5 (Cu-1.5Mn), QMn5 (Cu-5Mn), etc.
Chrome bronze is a copper alloy containing 0.4%~1.1% Cr.
Chromium bronze can be strengthened by quenching aging or quenching cold deformation aging treatment.
At the eutectic temperature of 1072 ℃, the maximum solubility of chromium in copper is 0.65%.
With the decrease of temperature, the solid solubility decreased sharply, and Cr particles were precipitated after the solid solution and aging treatment.
On the one hand, the addition of chromium can obviously improve the recrystallization temperature and thermal strength of the alloy;
On the other hand, the conductivity of copper decreases slightly.
The conductivity of solution treated chromium bronze rod is 45% IACS, and it rises to 80% IACS after aging treatment.
The softening temperature of aged chromium bronze is 400 ℃, twice that of cold worked copper.
This alloy can be used in the casting state and deformation state.
When Al and Mg are added as alloy elements of chromium bronze, a thin, dense oxide film firmly bonded with the base metal can be formed on the surface of Cu Cr alloy, which improves the high-temperature oxidation resistance and heat resistance of the alloy.
The content of Al and Mg in the alloy is usually not more than 0.3%.
Cadmium bronze is a special bronze with cadmium as the main alloy element.
Sometimes 0.35%~0.65% chromium is added.
Cadmium and copper form a solid solution at high temperature, and the solid solubility in cadmium and copper decreases sharply with the decrease of temperature.
Due to the low content of cadmium, the particle strengthening effect of precipitated phase is very weak.
Therefore, the alloy cannot be age hardened by heat treatment, and can only be strengthened by cold deformation.
It has high conductivity and thermal conductivity, good wear resistance, wear reduction performance, corrosion resistance and processing performance, and is widely used to manufacture conductive, heat-resistant and wear-resistant parts of electrical devices.
The volatile matter of cadmium is toxic.
It shall be prepared by melting method, and protection shall be paid attention to during melting.
The grade of domestic cadmium bronze is QCd1.
Cadmium bronze materials include plate, strip, rod and wire.
The main applications are: motor commutator, switch element, spring contact, waveguide cavity, transmission line with high strength, joint and contact welding electrode and roller, etc.
Zirconium bronze is a kind of special bronze with zirconium as the main alloy element.
A small amount of zirconium is sometimes added to improve the strength.
Common grades are QZr0.2 and QZr0.4.
It has good thermal strength and creep resistance, and has good plasticity and conductivity at high temperature.
It is made by the melting method.
It is mainly used as resistance welding parts, high-strength electrode materials, etc.
Zirconium bronze is more and more widely used in iron and steel industry for its high conductivity, thermal conductivity and easy processing.
Chrome zirconium bronze
Chromium zirconium bronze has high strength and hardness, electrical conductivity and thermal conductivity, good wear resistance and wear resistance.
After aging treatment, the hardness, strength, electrical conductivity and thermal conductivity are significantly improved, and it is easy to weld.
It is widely used for motor commutator, spot welding machine, seam welding machine, electrode for butt welding machine, as well as other parts requiring strength, hardness, conductivity and conductivity at high temperature.
The electric spark electrode can be used to produce an ideal mirror surface, with good upright performance.
It can achieve the effect that is difficult to achieve with pure red copper such as flaking.
It is good for difficult-to-machine materials such as tungsten steel.
Titanium bronze refers to the copper alloy with titanium as the main alloy element.
Titanium bronze is a new type of elastic material with good cold and hot workability.
It can also be strengthened by heat treatment, which greatly improves the properties of the alloy.
For example, the tensile strength can be increased from 686MPa to 1009MPa.
Titanium bronze can be used to manufacture high strength, high elasticity and high wear resistance elastic elements, electrical switches, relay elastic elements, membrane boxes, diaphragms, gears, bearings, bearing pads, bearing sleeves, etc.
Magnesium bronze belongs to magnesium copper alloy.
The grade of domestic magnesium bronze is QMg0.8.
Magnesium bronze is a Cu Mg binary alloy, which is generally used as cable and other conductive materials and can replace cadmium bronze in many aspects.
Magnesium bronze is mainly supplied in the form of wire, which is mainly used to manufacture conductive components such as cables and aircraft antennas.
Iron bronze is a kind of bronze with iron as the main element.
Copper iron alloy (iron bronze) represented by C19400 alloy (America).
Due to the precipitation of iron during heat treatment, the strength and heat resistance of the alloy are improved.
The tensile strength in the hard state can reach 415-485MPa, and the conductivity can reach 60% IACS.
It is widely used as lead frame materials for integrated circuits, and has been listed in the ASTM B465-85 standard of the United States.
At the same time, C19200, C19500 and C19600 alloys are also included in this standard.
Their iron content is 0.8% ～ 12%, 10% ～ 20% and 9% ～ 12% respectively, and their phosphorus content is 0.01% ～ 0.04%, 0.01% ～ 0.35% and 0.25% ～ 0.35% respectively.
The Chinese iron bronze equivalent to C19400 alloy is QFe2.5-0.1.