Metal red-brittleness is a dangerous phenomenon in which metal loses its plasticity and becomes brittle when heated to red heat temperatures (approximately 600—1000°C). In this temperature range, metal is particularly vulnerable: even minor external influences can cause microcracks and damage the structure. This can happen both during the hot processing stage (forging, rolling) and during the operation of products at high temperatures.
The problem of red brittleness is especially relevant in metallurgy and mechanical engineering, where the reliability and durability of materials directly affect the safety of equipment and structures. Understanding the causes of this phenomenon and methods for its prevention can significantly improve product quality.
The main causes of red fragility
Redness is due to both the chemical composition of the metal and its internal structure. Let's consider the key factors that contribute to its occurrence.
Harmful imperficities
Some chemical elements significantly impair the plasticity of metals at high temperatures:
- Sulfur (S): one of the main factors of red fragility. It forms a brittle compound with iron — iron sulfide (FeS), which, when heated, is released along the grain boundaries, reducing plasticity and causing fracturing.
- Phosphorus (P): forms brittle compounds with iron and further reduces plasticity at high temperatures, increasing the risk of destruction during deformation.
- Oxygen, nitrogen, carbon and other elements: participate in the formation of oxides, nitrides and carbides that degrade the microstructure of the metal.
Structural features
The metal structure and crystal lattice defects also affect the material's tendency to become red brittle:
- Structure heterogeneity: the uneven distribution of phases and impediments can locally change the properties of the metal, which reduces its plasticity and increases brittleness.
- Defects crystal lattice: vacancies, dislocations and other imperfections disrupt the movement of atoms and dislocations in the metal, which, in turn, reduces its plasticity and increases its tendency to crack.
Temperature and deformation conditions
Temperature conditions and the rate of deformation also play an important role in the occurrence of red brittleness:
- Temperature range: red brittleness usually occurs when the metal is heated to certain temperatures, which may vary depending on the structure and composition of the alloy. In this temperature range, the metal becomes more brittle and prone to cracking.
- Deformation rate: at a high processing speed, the metal does not have time to relax and adapt to changes. This prevents the even distribution of stresses, increasing the risk of cracks and other defects.
Thus, eliminating red brittleness requires an integrated approach at all stages of production.
Methods for combining the red fragility of metals
To prevent red breakdown, it is important to carefully monitor chemical composition metal, optimize the structure and technological parameters of processing in order to improve plasticity and reduce the tendency to crack at high temperatures. The main measures are listed below.
Chemical composition control
One of the main ways to combat red brittleness is to strictly control the chemical composition of the metal. This includes:
- Decrease in sulfur and phosphorus concentrations: since sulfur and phosphorus are the main culprits of red brittleness, it is important to minimize their content in the metal. This is achieved through the use of high-quality raw materials and modern methods of smelting and refining.
- Control of other contaminants: In addition to sulfur and phosphorus, it is necessary to monitor the content of other elements, such as oxygen, nitrogen and carbon, which can also affect red brittleness.
- Adding alloying elements: the introduction of alloying additives can improve the plasticity of the metal and reduce its tendency to red brittleness. For example, manganese binds sulfur to less harmful compounds, improving plasticity.
Optimization of heat treatment
Well-chosen technology heat treatment can significantly change the structure of the metal and increase its plasticity:
- Annealing: heating the metal to a certain temperature and then slowly cooling it helps to eliminate internal stresses, improve the microstructure and increase the ductility of the metal.
- Normalization: heating the metal above the upper critical point and cooling it in air contributes to a more uniform metal structure with improved mechanical properties.
Technological methods for metal processing
To reduce the risk of cracking during hot deformation, the following are used:
- Control of deformation rate: reducing the speed of machining (forging and rolling) allows the metal to better adapt to changes and reduces the risk of cracking.
- Optimization of the temperature regime: maintaining a safe temperature range during processing helps to avoid conditions under which red brittleness may occur.
- Modifying additives: the introduction of small amounts of rare earth elements can improve the microstructure and strength characteristics of the metal, which reduces its tendency to red brittleness.
Modern approaches to managing the structure and composition of metals make it possible to almost fully eliminate red brittleness while complying with technological discipline.
The role of PZPS in the production of high-quality materials
Special attention is paid to the problem of red brittleness in the production of precision alloys — special materials with precisely controlled chemical composition and unique physical and mechanical properties.
Precision alloys are widely used in high-tech industries: aerospace industry, electronics, medicine and precision mechanical engineering. They may have magnetic, superconducting properties, increased strength and other specific properties.
Even minimal amounts of harmful impurities (sulfur, phosphorus, oxygen, nitrogen) can significantly degrade the mechanical properties and magnetic characteristics of precision alloys. Therefore, the PZPS is implementing a whole range of measures to ensure the stable quality of alloys:
- Strict control chemical composition: high-precision analysis methods are used to determine the content of all elements in the alloy, including harmful impurities. This makes it possible to produce materials with a strictly controlled chemical composition.
- The use of pure raw materials: high-quality raw materials with a low content of impurities are used for the production of precision alloys.
- Modern smelting and refining technologies: various methods are used, including vacuum melting, which minimize the amount of harmful impurities and compounds.
- High accuracy of production processes: all stages of production, from smelting to final processing, are carefully monitored to ensure the quality of the alloy.
Limiting the content of harmful impurities in precision alloys makes it possible to achieve high performance characteristics, reliability and durability of products made from these materials.
At the PZPS you can buy cold rolled strip made of precision alloys of the following grades:
- Soft magnetic alloys: 49K2FA-VI, 27KH, 50N, 50NP, 79NM, 80NM, 81NMA.
- Alloys for elastic elements: 40KHNM, 17HNGT, 36NHTYU.
- With increased electrical resistance: X15YU5, X23U5, X23YU5T, X20N80N, X15N60N.
- With stable TCLR: 29NK, 33NK, 36N, 42N.
The whole products is produced in accordance with strict quality standards and can be adapted to specific customer specifications.
Contact usto order cold-rolled precision alloy strip or get advice on issues metallurgical processing. Our experts will answer your questions in detail and help you find the best solutions for implementing the most complex projects.
