Quality control is a set of actions aimed at verifying that the characteristics of materials comply with current standards and established technical requirements. It allows you to identify defects and deviations from specified parameters, prevent the use of low-quality products in production, minimize defects and guarantee high performance characteristics of final products. There are several methods for controlling the quality of materials. We'll take a closer look at each of them below.
Visual control
The method is based on a visual inspection of materials or products in order to identify defects on their surface, including discrepancies in color, shape and other visible signs.
The advantages of visual inspection:
- Easy and affordable — no complicated devices or tools are required — conventional lighting equipment and, possibly, magnifying devices (magnifiers) are sufficient.
- Quickness — the inspection is carried out fairly quickly, which makes it possible to quickly identify defects.
- effectivity — this method of control does not require significant equipment costs.
Disadvantages of visual control:
- Limited accuracy — does not reveal hidden defects.
- Dependence on the operator's experience and qualifications, what may affect the results of the control.
Major defects, which can be identified by visual inspection:
- Cracks — a defect caused by improper cooling, overloads or casting errors.
- Porosity — indicates a violation of the technological process during casting or cooling.
- Sinks — arise from improper production technology or contamination in the process.
- Corrosion marks — appear on the surface of the material in the form of stains, rust or other signs of destruction, indicate unfavorable storage or transportation conditions.
- Scratches — arise from improper handling of materials or tools. They lead to a decrease in the strength of the product and a deterioration in its appearance.
- Burrs — are formed when cutting and processing materials. They may damage the geometry or damage other parts of the product.
Visual inspection can be carried out as in production process, and at the final stages, during the final inspection of product quality.
Measurement control
It involves the use of specialized measuring instruments to determine the exact physical characteristics of materials: size, shape, weight and other parameters. It is more accurate than visual control and allows obtaining data with a high degree of reliability. It requires certain skills and the availability of specialized equipment.
The most commonly used instrument for measuring control is micrometer. This is a high-precision instrument designed to measure the linear dimensions of objects with an error of up to 2-50 microns, depending on the type of device and measurement conditions.
In the production of metal tape, micrometers are used to control the thickness of the product at various stages of production, which allows:
- make sure that the finished product meets the specified specifications;
- promptly identify deviations from the norm and adjust production parameters;
- prevent the production of products that do not meet thickness standards;
- reduce the number of scraps and reduces the cost of processing or recycling the material.
There are micrometers mechanical et electronic:
- mechanical they have a simple design and are most often used for rough measurements;
- electronic they are equipped with digital displays, have minimal error, and may have additional functions: automatic calibration or storing results in memory.
Measuring devices make it possible to reduce the influence of the human factor and obtain objective data. Early detection of deviations from the norm helps to quickly resolve problems and minimize the likelihood of producing defective products.
Chemical analysis
The process by which to determine chemical composition materials and their compliance with established quality standards. It can be carried out using various methods, such as:
- Spectroscopy — is based on the interaction of a substance with electromagnetic radiation. Depending on what type of radiation is used (ultraviolet, visible, infrared, X-ray, etc.), it makes it possible to determine the composition of the substance, its concentration and other characteristics.
- X-ray fluorescence (XRF) analysis — a method in which the elementary composition of the material is determined by measuring the radiation that occurs when exposed to X-rays. It allows you to accurately determine the chemical composition even in complex multicomponent materials.
- Atomic emission analysis (AEA) — based on measuring the radiation spectrumemitted by atoms or ions that are in an excited state. They are used to determine the elemental composition of materials, since each element has a unique radiation spectrum.
For rapid analysis of PZPS, they are used handheld spectrometer — a device that allows you to quickly assess the chemical composition, which is especially important in the process of quality control on production lines.
To accurately determine the chemical composition, use X-ray fluorescence and atomic emission devices. They have increased data accuracy and reliability, which is especially important in the production of precision alloys, where even minor deviations from a given composition can significantly affect the characteristics of the finished product.
Mechanical tests
The method is aimed at determining the performance properties of steels and alloys, as well as their ability to withstand external loads. The main goal is to obtain information about mechanical properties, such as hardness, strength, ductility, impact strength and others.
The main types of mechanical tests:
- Strength tests (tensile, compression, bending, impact) is a test of the material's ability to withstand static or dynamic loads.
- Hardness tests — measuring the resistance of the material to deformation when pressed or scratched.
- Test for plasticity — assessment of the material's ability to change shape without destruction.
Mechanical tests are needed to evaluate specialized materials used in critical structures and extreme conditions. For example, for steels and alloys of the following grades:
- 40KHNM, 36NHTYU, 17HNGT — used in elastic elements: springs, membranes. They must have high strength and elasticity.
- 12X18N9, 12X18H10T, 10X17N13M3T — are highly resistant to corrosion and are used in an aggressive environment.
- 60S2A, 65S2VA, 65G, 70, 70S2HA — used in the manufacture of springs, springs and other products that experience cyclic loads.
- 20X13, HN78T — used under conditions of high temperatures and high loads, for example, in gas turbine engines and heat exchangers.
The use of various methods and tools during mechanical testing makes it possible to use this method in scientific research, design and quality control.
Physical tests
They are aimed at determining the physical characteristics of materials that are necessary to assess their properties and meet specified requirements. They help to determine:
- Coercive force — the ability of the material to resist magnetization or demagnetization.
- Electrical resistivity — a characteristic that determines the ability of a material to resist the flow of electric current.
- Linear Expansion Temperature Coefficient (TCLR) — reflects the degree of change in product size under the influence of temperature.
Materials for which physical testing is particularly important:
- Ribbons and sheets from electrical steel brands 20895, 20880, 20860, 20832, 21895, 21880, 21860, 21832 are used for the manufacture of electrical circuit elements.
- Soft magnetic alloys 50N, 50NP, 79NM, 80NM, 81NMA, 49K2FA-VI, 27KH are used in transformer cores, relays and other magnetic devices.
- Alloys with high electrical resistance X15Yu5, X23Yu5, X23U5T, X20N80N, X15N60N are used in heating elements, resistors and other devices where it is important to maintain the stability of electrical parameters.
- Alloys with a specified TKLR 29NK, 36N, 42N — used in precision instruments, glass-metal joints and other structures where it is important to minimize thermal deformations.
Physical tests help to ensure that steels and alloys meet technical requirements, determine their suitability for specific applications, and improve the reliability and durability of products.
Microscopic analysis
The main goal of the method is to study the microstructure of objects to identify microdefects, structural features and assess the quality of the material.
Principles of microscopic analysis:
- Research tools:
- optical reflected light microscopes — make it possible to study surface structures and identify major microdefects;
- scanning electron microscopes (SEM) — used for a more detailed study of the microstructure, they help to detect the smallest details of the surface and internal structure.
- Analysis objects:
- metals, alloys, ceramics, polymers and other materials;
- reveal features such as granularity, phase composition, porosity, cracks and other defects.
- Research process:
- sample preparation: grinding, polishing and sometimes etching are carried out to make the microstructure more visible;
- analysis under a microscope: the researcher studies the structure in detail and records the identified defects in the product.
Microscopic analysis allows us to better understand the nature and behavior of various materials at the micro level, which is especially important in the production of thin tape.
Non-destructive testing (NDT)
NC is a set of methods that make it possible to assess the quality of materials, products or structures without destroying or damaging them.
The main methods of NC:
- Ultrasonic testing (UZC) — used to identify internal defects: cracks, voids and delamination. It is based on the passage of ultrasonic waves through the material.
- Capillary control — allows you to detect surface cracks with a special dye.
- Magnetic control — used to identify surface and subsurface defects in ferromagnetic materials.
- X-ray inspection (RK) — makes it possible to detect defects inside the material using X-rays, creating an image of the object's structure.
- Electromagnetic and eddy current testing — used to analyze conductive materials.
- Thermal imaging control — helps to identify defects due to changes in the temperature characteristics of the object's surface.
Non-destructive testing is used to ensure the safety and reliability of products in the following areas:
- Mechanical engineering and aviation industry
- Weld inspection.
- Identification of cracks, corrosion and other defects in metal structures.
- Construction
- Assessment of the strength of concrete structures.
- Detection of cracks and voids in walls, ceilings and other building elements.
- Energy
- Diagnostics of pipelines, heat exchangers, turbines and other equipment.
- Detecting corrosion, leaks and deformations.
- Transportation
- Assessment of the condition of railways, bridges and highways.
- Control vehicle parts.
- Chemical industry
- Checking the tightness of tanks, tanks and pipes.
- Detection of leaks and defects in systems for storing and transporting substances.
The choice of a specific NC method depends on the type of material, the features of the product or design, and the required depth of testing (surface or internal).
PZPS products: quality control at every stage of production
Here you can buy high-quality cold-rolled strip that meets the requirements of GOST 503-81, as well as products made from special materials, including nichrome, analogues of foreign family alloys, precision alloys 27KH, X20N80 et al.
The PZPS guarantees the reliability, durability and compliance of each product with GOST requirements and international standards. We invite you to check out our services et manufactured products et place an order on high quality tape!
