CC BY
11
МЕТАЛЛУРГИЯ
SRSTI 53.49.19
https://doi.org/10.48081/GDLO8047
*А. Zhakupov1, A. Bogomolov2, A. Zhakupova3
u'3Toraighyrov University, Republic of Kazakhstan, Pavlodar
non-destructive method for DETERMiNiNG the mechanical properties of rolled steel
This article describes the developed methodology for the prompt and reliable determination the mechanical properties quantitative indicators of the heat-treated steel products by a non-destructive method. For these cases, the non-destructive method of testing steel products is the most optimal option, due to the fact that it does not require destruction of the controlled sample and provides for the possibility of the product further operation. The use of non-destructive testing methods also contributes to significant savings in material and time resources.
The essence of the method described in this work lies in the initial study of steel samples, measuring their coercive force, maximum magnetic permeability and residual magnetic induction for subsequent statistical analysis to determine the relationship between mechanical and electromagnetic properties. As a result of finding this correlation and checking its reliability, it becomes possible to determine the ultimate strength, yield strength and relative elongation on finished products, which are normalized indicators of the steel structural products strength properties.
The proposed non-destructive methodfor determining the mechanical properties will allow its use in the production flow, while having the reliability of determining the quality indicators above 96 %.
Keywords: non-destructive testing, mechanical properties, rolled steel, coercive force.
Introduction
At metallurgical and machine-building enterprises, serial and mass production of steel products is carried out, the given structure and mechanical properties of which are achieved by certain heat treatment modes. Possible inconsistencies in the chemical composition of the products material and the modes of their heat treatment lead to unacceptable deviations in the properties of the products and require control of each product unit. Direct methods for determining mechanical properties and structure are destructive and cannot be used to determine the quality of products intended for use.
In addition, quality control with destruction, as a rule, requires taking templates and making samples for subsequent testing, which is a laborious and expensive operation [1-8].
The feasibility of introducing a non-destructive magnetic control method into production is justified by numerous advantages, of which these are:
- saving control time, due to the absence of the need to select templates and prepare samples for testing;
- cost savings due to the rejection of low-quality metal, blanks before expensive machining;
- replacement of bulky test equipment used for destructive testing methods with small-sized instruments, which also saves production space;
- the possibility of further use of the controlled product.
Materials and research methods
The objects of research were samples of 09Mn2Si steel pipes.
Previously, the samples were heated to 900 °C, quenched in water and tempered at various temperatures from 500 to 700 °C. Then, coercive force Hc, maximum permeability and residual magnetic induction Br were measured. After measuring the magnetic indicators, the tensile strength o+TS, yield strength a and elongation £ were determined by the tensile method of a steel sample [9].
The laboratory equipment was used for the study: a tensile electromechanical machine for measuring mechanical properties in accordance with GOST 1497-84 -«Metals. Tensile test methods», coercimeter KRM-Ts-K2M for measuring the coercive force in accordance with GOST 30415-96 - «Steel». Teslameter EM4305 for measuring residual magnetic induction in accordance with GOST 12119.1-98 - «Electrical steel. Methods for determining magnetic and electrical properties».
Results and discussion
After heat treatment of the samples, using a coercimeter and a teslameter, the maximum values of magnetization and strength were measured, and, accordingly, the coercive force and residual magnetic induction, the values of which are indicated in the diagrams in Figure 1.
Having determined the maximum values of the tension and magnetization of the samples, the maximum magnetic permeability of each sample was calculated according to formula 1, the values of which are summarized in Table 1.
¡¿max ^Tnax^Ariaxj, (1)
where Bmx - maximum magnetic field strength of the sample, T;
H - maximum value of sample magnetization, A/m.
Boci, №>rT(m*u)
Figure 1 - Magnetic properties of a 09Mn2Si steel specimen
The values of the coercive force corresponded to the values of the magnetization at zero magnetic field strength, and the values of the magnetic induction, on the contrary, to the value of the intensity at zero magnetization.
Table 1 - Values of the maximum magnetic permeability of steel samples
Steel Tempering temperature, ^
500 550 600 650 700
09Mn2Si 73,7 72,2 73,5 81,6 108,0
After the measurements of the magnetic characteristics were carried out measurements of the actual mechanical characteristics, the results of which are summarized in Table 2. In this case, the variable parameter of heat treatment was the tempering temperature in the range from 500 to 700 °C.
Table 2 - Values of mechanical properties of test specimens
Steel Tempering temperature, ^ Tensile strength, МPа Yield strength, МPа Relative elongation, %
09Mn2Si 500 755 645 9
550 684 583 10
600 617 539 11
650 602 518 13
700 586 505 14
Applying regression analysis in Excel program, a mathematical model was derived for the control of mechanical properties by a non-destructive method for steel 09Mn2Si. To determine the tensile strength:
To determine the yield strength:
To determine the relative elongation:
To confirm the reliability of the proposed method for determining the mechanical properties, tests were carried out with measurements according to the proposed method. For this, three items of steel 09Mn2Si were taken and thermally treated according to the selected mode, for example, a tempering temperature of 620 °C was taken [10]. Then, the magnetic parameters were measured on each tempering product. Substituting the average of three values for each of the parameters into the equations of dependencies available for a given steel, determined the calculated values aTS, aYS and e. After that, standard samples for tensile testing were made from each product and the actual values of mechanical properties were obtained. Table 3 shows the calculated values determined by the equations of dependencies and the actual values of the mechanical properties determined by tension the standard samples, which confirm the reliability and accuracy of the proposed method for quality control of steel products heat treatment. The measurement error was less than 4 %.
Table 3 - Convergence of results
Mechanical properties of steel 09Mn2Si products at a tempering temperature of 620 °C
Calculated (by regression equations) The actual (by tensile tests)
^TS, MPa 715 ^T S , MPa 731
C>YS, MPa 668 °YS, MPa 693
e, % 16,2 e, % 16,5
Conclusions
The use of three magnetic parameters in the complex during the inspection of steel products contributes to an increase in the reliability and accuracy of measurements, in comparison with one-parameter control, which is confirmed by an error of no more than 4 %.
In addition, improving the technology for determining the mechanical properties of steel products heat treatment will reduce the time for testing, due to the absence of the need to select templates and prepare samples for testing, eliminate the use of bulky test equipment used for destructive testing methods with small-sized devices, and will also enable further use controlled item.
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Material received on 20.09.21.
*А. Жакупов1, А. Богомолов2, А. Жакупова3
1,2,3ТораЙFыров университет^ Казахстан Республикасы, Павлодар к. Материал 20.09.21 баспаFа TY^i.
БОЛАТ ИЛЕМНЩ МЕХАНИКАЛЫЩ ЦАСИЕТТЕР1Н АНЬЩТАУДЬЩ Б¥ЗБАйТЫН ТЭС1Л1
Бул мацалада болат втмдерт бузбайтын эдютермен термиялъщ вцдеудщ механикалыц цасиеттерШц сандыц кврсеттштерт жедел жэне ceHiMdi аныцтау ушт эзipленген эдктеметц сипаттамасы келтiрiлген. Бул жагдайларда болат втмдерт бацыыаудыц бузбайтын ddici бацылаудыц ец жацсы нусцасы болып табылады, вйткет ол бацыланатын yлгiнi бузуды цажет етпейдi жэне внiмдi одан dpi пайдалану мумктдшн царастырады. Бузбайтын тестшеу эдютерт цолдану материалдыц жэне уацытша ресурстарды едэуip унемдеуге ыцпал етедi.
Осы жумыста сипатталган эджтщ мэт механикалъщ жэне электромагниттк цасиеттер арасындагы байланысты аныцтау ушт Keüi^i статистикалыц талдау ушт болаттыц эр маркасыныц улгыерт бастапцы зерттеу, олардыц коэрцитивтi кушт, максималды магнит еттзгштшн жэне цалдыц магниттк индукцияны влшеу болып табылады. Осы корреляцияны табу жэне оныц сетмдшгш тексеру нэтижестде дайын втмдерде болат цурылымдыц буйымдардыц бержтж цасиеттерШц нормаланган кврсеткiштерi болып табылатын уацытша царсылыцты, тр^тшж шегш жэне салыстырмалы узаруды аныцтауга мумктдж бар.
Механикалыц цасиеттердi аныцтаудыц усынылатын бузбайтын эдс сапа кврсеттштерт 96 %-га дешн аныцтаудыц сетмдшгше ие бола отырып, оны вндiрiс агынында пайдалануга мумкшдж бередi.
Кiлттi свздер: бузбайтын бацышау, механикалыц цасиеттер, илем, коэрцитивтi куш.
*А. Жакупов1, А. Богомолов2, А. Жакупова3
1,2,3Торайгыров университет, Республика Казахстан, г. Павлодар. Материал поступил в редакцию 20.09.21.
НЕРАЗРУШАЮЩИй СПОСОБ ОПРЕДЕЛЕНИЯ МЕХАНИЧЕСКИХ СВОЙСТВ СТАЛЬНОГО ПРОКАТА
В данной статье приводится описание разработанной методики проведения оперативного и достоверного определения количественных показателей механических свойств термической обработки стальных изделий неразрушающими методами. Для этих случаев неразрушающий метод контроля стальных изделий является наиболее оптимальным вариантом контроля, в связи с тем, что не требует разрушения контролируемого образца и предусматривает возможность дальнейшей эксплуатации изделия. Применение методов неразрушающего контроля так же способствует значительной экономии материальных и временных ресурсов.
Сущность описанного в данной работе способа заключается в начальном исследовании образцов каждой марки стали, измерении их коэрцитивной силы, максимальной магнитной проницаемости и остаточной магнитной индукции для последующего статистического анализа с целью определения взаимосвязи между механическими и электромагнитными свойствами. В результате нахождения данной корреляции и проверки ее достоверности появляется возможность на готовых изделиях определять временное сопротивление, предел текучести и относительное удлинение, являющиеся нормируемыми показателями прочностных свойств стальных конструкционных изделий.
Предлагаемый неразрушающий метод определения механических свойств позволит использование его в потоке производства, имея при этом достоверность определения показателей качества до 96%.
Ключевые слова: неразрушающий контроль, механические свойства, прокат, коэрцитивная сила.
