Services of the central factory laboratory

The central plant laboratory was established to control the quality of raw materials, rolled metal products and finished products to determine their compliance with regulatory requirements.

– chemical and analytical laboratory,

– metallurgy and mechanical testing laboratory,

– industrial sanitation and environmental control laboratory.

– Analytical and Organic Chemistry Laboratories,

– X-ray Spectral Analysis Group,

– Physical Control Methods Laboratory,

– Building and Molding Materials Group.

Hardness characterizes the resistance of a material to large plastic deformations. The most common methods of determining hardness involve the use of a special body, an indenter, in the material under test with such force that local plastic deformation occurs, resulting in an indentation of the indenter in the material. The value of hardness is judged by the imprint. Hardness determination by indentation is a soft test (a > 2 – Fig. 2.6).

Hardness testing is the most common method for determining material properties. This is due to a number of reasons: hardness testing is a non-destructive method, as the part can be used for its intended purpose after such measurement; hardness testing does not require high qualifications and, in addition, knowing the hardness, it is possible to judge other mechanical and technological properties.

One of the methods for measuring steel hardness is the Rockwell method. The hardness is determined by measuring the strain caused by the indenter pressing the material under test. Rockwell hardness is determined by the depth of penetration obtained during a two-step test. The symbol HR is used to indicate the Rockwell hardness, followed by a letter indicating the scale used for the test. For hand tools, scales B and C are commonly used. Scale C is used to determine the hardness of iron alloys, and scale B is used to determine the hardness of aluminum, copper, brass, and other mild steels. High hardness for hand tools is in the range of 55 to 60 HRC.

– Determination of the mass fraction of carbon and sulfur in alloys by the coulometric method;

– Determination of the mass fraction of boron (from 1-2%) in alloys by the potentiometric method;

– Chemical analysis of electrolytes;

– Development and implementation of new methods for determining the content of chemical elements in alloys by physical and chemical methods;

– The following methods are used for other analyzes: gravimetric; titrometric; photometric; electrochemical;

In macroscopic analysis, the structure or fracture is examined with the naked eye and a magnifying glass with a small magnification. The macroscopic analysis evaluates the metal structure in large areas, identifies the direction of fibers and the presence of metallurgical defects (cracks, hairs, gas bubbles, liquation, etc.).

Prior to macroanalysis, the surface of the part or sample to be examined is ground and etched with a special reagent. The fracture surface is examined without any prior preparation. Macro analysis is usually followed by micro analysis.

Microscopic analysis examines the structure under a high-magnification optical microscope. The microanalysis examines the location and size of grains, individual components of the metal structure, determines the depth of the layer after surface hardening with high-frequency currents and after chemical and thermal treatment, identifies the presence and nature of foreign inclusions, small defects, etc.

Prior to microanalysis, special microgroove samples are prepared and cut from the part. Their surface is polished to a mirror shine and etched with special reagents.

Samples for microstructure evaluation have a size of 0.5-1.0 cubic cm. The number of such samples and the places where they are cut are specified in the relevant technical specifications and standards, taking into account the size, purpose and method of manufacture of the objects under study.

Mechanical properties of materials, a set of indicators characterizing the resistance of a material to load, its ability to deform under load, as well as the peculiarities of its behavior during fracture

Temporary resistance, b

Tensile strength σt (temporary resistance) is the stress corresponding to the maximum load that a sample can withstand before fracture (temporary tensile strength).

Relative elongation, %

Relative elongation at break δ is the increase in the remaining length of the specimen relative to the initial design length; it is expressed as a percentage.

Relative contraction, %

Relative contraction at break is the decrease in the cross-sectional area of the specimen at the point of break, expressed as a percentage of the initial cross-section.

The bending test of samples cut from sheet, strip or shaped steel (GOST 14019-80) assesses the ability of steel to undergo cold plastic deformation.

Determine: the mass fraction of carbon in steels and alloys by automatic coulometric titration using the AN-7529 express carbon analyzer in accordance with GOST 22536.1 and GOST 12344. The mass fraction of manganese and chromium is determined by the titrimetric method25,55. GOS12346, GOS12348, GOS12350. Sampling is carried out in accordance with GOST7565.

The mass fraction of tungsten, molybdenum, titanium, and vanadium is determined using a Spectrum styloscope by the brightness of spectral lines by comparison. This method is also used to determine the content of chromium and manganese in products that cannot be destroyed.

One of the main characteristics of a metal is its hardness. We determine the hardness of ferrous and non-ferrous metals and alloys using the Brinell and Rockwell method on products and samples, and prepare samples for testing. We measure hardness using stationary and portable hardness testers. We use portable dynamic hardness testers to measure hardness on large-sized products, parts with complex shapes, etc.

The mechanical properties are obtained by tensile testing of cylindrical specimens with a diameter of 3 mm or more and flat specimens with a thickness of 0.5 mm or more at normal temperature. Tests are performed on UMM-5 and P-20 tensile testing machines. As a result of the tests, we determine the temporary resistance, relative elongation and relative contraction. Samples are manufactured and tested in accordance with GOST1497.