The paper deals about the influence of heat and chemical-heat treatment of construction steel 100Cr6 and alloy steel X210Cr12, which were treated according to their corresponding norms. The steel ...X210Cr12 was also treated in an unconventional way. The influence of the material structures and hardness on the abrasion wear resistance was studied. The influence of nitridation was considered in a way how to increase the abrasion wear resistance and how the heat treatment affects the hardness and the quality of the nitrided layer. The nitridation with diffusion annealing of the tested materials caused a decrease and also an increase of the materials wear resistances.
The aim had been to study changes in the properties of aluminium alloy AlSiMgMn. Influence of SPD of the mechanical properties had increased (Rm by 86 MPa, Ro0,2 by 175 MPa, while A had decreased to ...20 %). The corrosion potentials had been evaluated in the environment of H2O and in SARS. After SPD was observed in the environment of H2O, that resistance had increased by -218 mV and after exposure up to 1 000 min there was a slight deterioration of resistance in SARS. On the surface specimens after SPD were observed higher quantities of corrosion products. After SPD was observed fatigue characteristics in torsional stress in the oblique branches Wohler curves showed favourable characteristics of about 35 %.
The properties of ultra fine grained nano Titanium made by ECAP technology and pure cold drawn Titanium are analyzed in this contribution. Mechanical properties, resistance to wear by a ZrO2 ball ...friction test, corrosion in a Hank solution by the Tafel’s method at temperatures 21 °C and 37 °C, and fatigue properties in torsion were evaluated and compared. The fatigue fracture started with crack formation parallel to the specimen axis and it was finalized by cracking in the angle of maximum shear stress. Titanium powder has been observed on the sample surfaces which indicated the crack initiation. Nano structure Titanium showed higher resistance to corrosion less wear by friction, and to a limited number of cycles higher fatigue strength.
Mechanical properties of a steam tube made of CrMo creep resistant steel are analysed in this contribution after up to 2, 6 times 10(5) hours service life in creep conditions at temperature 530 ...degree C and calculated stress level in the tube wall 46, 5 MPa. During service life there were in the steel gradual micro structure changes, first pearlite spheroidization, precipitation, coaugulation and precipitate coarsening. Nevertheless the strength and deformation properties of the steel (R(e), R(m), A(5), Z), and the resistance to brittle fracture and the creep strength limit, were near to unchanged after 2,1 times 10(5) hours in service. The steam tube is now in service more than 2, 6 times 10(5) h.
The paper analyses the influence of strain rate on the behaviour of un-alloyed steels with Re (yield strength) in the range of 210 … 550 MPa in the deformation process. It analyses the results of the ...influence of strain rate ranging from 10-3 to 2,5•102s-1 on the yield strength, the ultimate tensile strength (Rm), the elongation (A) and the reduction of area (Z). Achieved results of strain rate in relationship on values of Erichsen number IE are also given. By increasing of strain rate ranging from 10-3 to 2,5•102s-1 the ratio Re/Rm is increased, whereas it was observed more intensively for steels with the lower value of Re. By increasing of strain rate up to 1 s-1 are IE values of tested steels increased, whereas the ratio Re/Rm was equal 0,82. After exceeding of this strain rate was the ratio Re/Rm increased and IE value is remarkable decreased.
The paper analyses the properties of deep-drawing sheets of three grades (Re = 320 to 475 MPa), surface-treated with hot-dip galvanizing, made of microalloyed steels. Deformation properties are ...assessed using tensile tests, technological Erichsen or cupping tests. These characteristics, as well as the behaviour of the surface layer, are also investigated under dynamic conditions (modified Erichsen test using a drop tester), or using flat bending fatigue tests. Using microscopic analysis the deformation properties of the surface layer are evaluated. The results show the compactness of the surface layer, high deformation characteristics, as well as fatigue properties of the investigated deep-drawing materials, suitable for application in the automotive industry.
The paper analyzes the fatigues properties of galvanized microalloyed steel sheets H220LAD and H380LAD. Under flat bending conditions and the symmetrical cycle, the fatigue limit of the H220LAD sheet ...is σCo = ± 152 MPa and that of the H380LAD sheet is σCo = ±188 MPa, and the fatigue limit to tensile strength ratio is 0,41 and 0,37, respectively. During fatigue tests with an increasing number of cycles or an increasing stress value, the degradation of the zinc coating increases (relief formation, damage of integrity). As a result, local corrosion, but also continuation of fatigue damage after 107 cycles, and hence corrosion fatigue, can take place during operation.
The paper analyzes the influence of the impact rate of up to 120 ms-1 with a constant energy on the relative compression of high-grade unalloyed steels, Cu and Zn, and the evaluation of energy ...consumed during the impact bending test at the impact rate of up to 80 ms-1. Based on the experiments made, relationships for the prediction of the influence of the strain rate within the range of 10-3 - 2.5.103 s-1 on the mechanical properties of high-grade unalloyed steels with the yield point of 210-450 MPa and microalloyed steels with the yield point of 300-600 MPa are presented.
Prvo, članak daje pregled više od sto godina duge povijesti proizvodnje bešavnih čeličnih cijevi, naročito u posljednjih 15-20. godina 20. stoljeća. Nastavak članka daje, uz tehnološke parametre za 4 ...valjaonice i usavršavanje postupaka proizvodnje bešavnih čeličnih cijevi početkom 21. stoljeća.
The article first give a review more of hundret years long history of seamless steel tube production, especially during the last 15-20 years of the 20th century. Prolongation, article give ...technological indices for 4 mills (automatical, continuous mill, pilger, Assel), and perfectation of processes seamless steel tubes production at the begining of 21st century.
