Strength Properties Of Metal Research Articles

Strength Properties of Metal–Intermetallic Laminated Composites in Three-Dimensional Model

The paper studies the instability of the plastic flow and fracture of metal-intermetallic laminated composites using a three-dimensional multi-scale model of the dislocation kinetics and mechanics of the elastoplastic medium under the dynamic high-temperature compression. The suggested theoretical stress-strain curves represent the behavior of laminated composites at different deformation temperatures and layer arrangements. It is shown that the inclusion of soft plastic metallic layers into the intermetallic matrix stabilizes the plastic flow of laminated composites, significantly increases the plasticity and time to fracture and decreases the deformation resistance. The layer arrangement has no great effect on the stability of plastic deformation.

Изучение микроструктуры и механических свойств низкоуглеродистой стали, микролегированной бором

The paper presents the results of the study of non-metallic inclusions, the structure and mechanical properties of low carbon steel, microalloying by boron. The study of the amount and composition of nonmetallic inclusions showed that with the introduction of boron the volume fraction of oxide and oxysulfide inclusions increases and the volume fraction of sulfide inclusions significantly decreases. At the same time, the alloying of steel with boron increases to 99.7% the proportion of inclusions with a size of no more than 5 microns against 80.6% in the metal without boron. In the metal with boron, nonmetallic inclusions larger than 10 μm are absent, while in the metal without boron their share is 13.6%. Studies have shown that in a metal containing 0.011% boron, independent boron-containing inclusions were not detected. Boron was not detected in the composition of the studied nonmetallic inclusions. In all samples, steel nonmetallic inclusions are represented mainly by oxide, oxysulfide and sulfide inclusions. In the boron-free steel, a small amount of perlite is present along with the ferritic phase. Steel microalloying by boron is accompanied by the formation of a dispersed ferrite-bainite structure, which consists of fine-grained ferrite with bainite sites with a tendency to form bainite strips along the rolling direction. The microhardness of ferrite and perlite in steel without boron does not exceed an average of 180 and 214 HV10, respectively. It is noted that the presence of boron in steel in an amount of 0.011% increases the microhardness of ferrite to 260 HV10 and bainite to 335 HV10. The mechanical properties of hot-rolled steel with a thickness of 10 mm from boron-containing low-alloyed steel, due to the predominant formation of small rounded inclusions with a size of no more than 5 microns and the formation of a fine ferrite-bainite structure, are characterized by enhanced strength properties with preservation of plastic characteristics. The absolute values of the yield strength and temporary resistance of steel with boron reach 575 and 650 MPa, respectively. With such strength properties of metal, high plastic characteristics are preserved. Rolled steel without boron is characterized by reduced to 540 and 610 MPa tensile strength and temporary resistance, respectively.

Analysis of changes in hardness of a metal surface layer in areas of high stress and methods of determining residual life of parts for mining machines

The methodological bases for determining the energy resource of mechanical transmissions details for mining machines are considered. Based on the analysis of the accumulation of damage in metal gears, a method of estimating residual life of coarse-toothed wheels by periodically measuring the hardness of the surface layer of the teeth is justified. The regularities in change of hardness of coarse-tooth gear, conditioned by a change in metal strength properties that take into account the micro- and macromechanisms of plastic and elastic deformation, distortion of the metal crystal lattice with formation and movement of vacancies and dislocations. Experimental setup was built and the results of laboratory experiments are given related to the process of destruction of non-standard samples under different loads. Comparison of dimensions and hardness values of the sample allows concluding that a larger deformation corresponds to a greater increase in hardness, their limit value for the material being in the fracture zone. It is established that the detected changes in the local hardness occurs in areas of increased stresses above the limit of proportionality and the work of fracture forces attributed to dislocations density adjacent to the fracture plane expressed in terms of hardness increment is constant.

An Experimental Study on the Strength Evaluation of Mechanical Press Joint

Mechanical press joining technique has been used in sheet metal joining processes because of its simple process and possibility of joining dissimiliar metals, such as steel and aluminum. The static and cyclic behavior of single overlap AI-alloy and steel(SPCC) joints has been investigate. Relationships were developed to estimate the strength of the joint taking into consideration base metal strength properties and the geometry of the joint. Fatigue test results have shown that fatigue resistance of the SPCC mechanical press joints is almost equal to that of the spot weld at the life of cycles. Also, the dissimilar material jointed specimen with upper SPCC plate and button diameter corresponding to the nugget diameter of the spot welded specimen has almost same strength as the same material jointed specimen and as the spot welded specimen.

Determination of the influence of halogens on the strength properties of metals

Determination of the influence of halogens on the strength properties of metals

Relationship of the strength properties of metals to their catalytic activity

Relationship of the strength properties of metals to their catalytic activity

Effect of nitrogen-hydrogen atmospheres on the refractory properties of nickel-base alloys

The problem of the variation in the strength properties of metals under the action of nitrogen--hydrogen atmospheres is very topical at present. In the majority of investigations the reaction of ammonia decomposition products with structural steels and alloys is considered principally from the point of view of chemicothermal treatment [1-4]. However, studies on evaluating the strength characteristics of metals during the action of ammonia on them and also on studies on corrosion in ammonia are few in number [5-12].