Pipe Metallurgical (Russia)

The results of experimental studies of one-sided friction stir welding of 10-mm-thick plates made of aluminum alloys 6082T6 (pressed profile) and 1565chM (the sheet positioned upstream of the working tool) are presented. Welded butt joints without internal defects are obtained. The tensile strength of the joints averages 210.9 MPa, which is 0.69 of the strength obtained for alloy 6082T6. The fracture of welds during the tensile test develops in the heat-affected zone on the side of alloy 6082T6. The tensile strength of the metal of the mixing zone is higher than that of alloy 6082T6. It is almost the same as for alloy 1565chM. The microstructure of the mixing zone consists of areas featuring a chemical composition corresponding to the chemical composition of the alloys to be welded or to the areas having partial mixing of alloys to be joined. At the same time, the metal of the mixing zone is resistant to intercrystalline corrosion. The heat-affected zone on the side of the 6082T6 alloy is the most susceptible to intercrystalline corrosion.

An essential element of enterprise economics and management is planning, which involves establishing standardized and target values to stimulate the efficiency of business processes. The article examines the genesis of the development and improvement of the calculation-analytical method for forming planned norms and standards within the system of material resource rationing. The current components of the mathematical model for metal rationing are described in detail. The basis for evaluating practical implementation aspects is the experience of JSC RUSNITI (Russian Research Institute for the Tube and Pipe Industry) in developing tools for scientifically and technically justified management of material resource (metal) consumption during the production of seamless hot-rolled pipes at the FQM (Fine Quality Mill) tube-rolling unit. The results of implementation are presented, including an improved rationing process achieved through in-depth differentiation of the calculation of specific components of the metal consumption coefficient. It is asserted that the development and implementation of rationing tools enhance business processes, particularly planning and resource conservation management.

The morphology of structural components in hot rolled pipes made of 38G2F steel has been studied by optical metallography. It is shown that the sections elongated along the rolling direction with a morphology different from pearlite are sections of upper bainite, the hardness of which is comparable to the hardness of pearlite (~290–300 HVμ). Plotting the thermokinetic diagrams (TKD) of the decomposition of supercooled austenite, as well as a joint analysis of the microstructure and hardness, allowed us to determine the minimum velocity Vcool ~ 0.5°C/s at which the bainite component in the pipe wall is formed. The temperature–time parameters of the decomposition of supercooled austenite with increasing austenitization temperature from 850 to 1000°C have been determined.

A method for the determination of Fetot, SiO2, P, V2O5, TiO2, Cr2O3, Ni, Cu, Zn in iron ore raw materials (i.e., pellets, iron ore agglomerate, aspiration dust and slag component of a scrap) by the method of atomic emission spectrometry with inductively coupled plasma (ICP-AES) has been developed using microwave sample preparation in analytical autoclaves. The composition of the acid mixture for the complete dissolution of the sample component, as well as the parameters of microwave decomposition, excluding the depressurization of the autoclave and the loss of sample elements which form volatile compounds are proposed. The developed method of microwave sample preparation in closed autoclaves makes it possible to decompose iron ore samples using the minimum amount of acid (17 cm3) in 45 min. Conditions for the determination of normalized elements in iron ore samples by the ICP-AES method after microwave sample preparation were determined: the operation parameters of the spectrometer were optimized, the analytical lines of each determined element free from spectral overlaps were selected, the efficiency of using cadmium as an internal standard was experimentally proved. The equations for calibration dependences and the ranges of determinable contents are presented. When using cadmium as an internal standard in the analysis of iron ore, a decrease in the value of the standard deviation from 0.17 to 0.04 is observed when determining Cr2O3; from 0.02 to 0.004 when determining Fe; from 0.03 to 0.002 when determining SiO2; from 0.015 to 0.008 when determining TiO2; and from 0.17 to 0.02 when determining V2O5. The correctness of the determination of the standardized elements by the developed method is evaluated, using certified reference samples (CRS) similar in composition to the analyzed material. The results of determining the standardized elements according to the developed methodology were compared with the data obtained using GOST-approved methods of analysis, and then checked in accordance with the Recommendations of RMG 76–2014. The developed ICP-AES technique is characterized by a wider linear range of the determined concentrations than that in GOST-approved techniques, thus providing determination of the components in iron ore raw materials that could not be controlled before.

Hеat-rеsistant nickеl-basеd allоys arе widеly usеd in thе dоmеstic aircraft industry, rоckеt еnginееring, and instrumеnt making. Incrеasing thе basic mеchanical and оpеratiоnal charactеristics оf thе mеtal is achiеvеd mainly by allоying thе basе with variоus еlеmеnts such as rhеnium, ruthеnium, and hafnium. Ноwеvеr, increasing the operational prоpеrtiеs can alsо bе achiеvеd by mеtal nitriding, as a rеsult оf which intеrstitial sоlid sоlutiоns arе fоrmеd (finеly dispеrsеd nitridеs), which incrеasе thе allоy strength. Тhе study is devоtеd tо thе nitriding prоcеss оf nickеl-basеd cоmplеx allоys. Variоus оptiоns оf thе nitrogen intеractiоn with thе mеlt arе cоnsidеrеd undеr cоnditiоns оf оpеn mеlting and prоcеssing with lоw-tеmpеraturе nitrоgеn-cоntaining plasma. Тhе use оf plasma-arc remelting allows оnе tо оbtain variоus gas typеs in the fоrm оf atоms, iоns, and mоlеculеs in plasma. Тhе first two forms are much mоrе activе than mоlеcular nitrоgеn, which lеads tо supеr-еquilibrium cоncеntratiоns in thе allоy. А thermodynamic analysis оf nitrogеn sоlubility in a nickеl-basеd mеlt was pеrfоrmеd during оpеn mеlting and undеr plasma-arc rеmеlting. Тhе nitrogen solubility in mоdеl EP741NP allоy was calculatеd dеpеnding оn thе partial prеssurе оf nitrоgеn abоvе thе mеlt surfacе and in thе plasma-fоrming gas. It was shоwn that trеatmеnt оf thе mеlt with nitrоgеn-cоntaining plasma makеs it pоssiblе tо оbtain highеr nitrogen cоntеnt in thе allоy. In this wоrk, mеtal temperature in thе contact zоnе with the plasma arc was еstimatеd using thе tеchniquе in which thе еvapоratiоn оf thе mеlt cоmpоnеnts frоm thе arc spоt arеa оccurs whеn thе mеtal bоiling pоint is rеachеd.