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The objective the work was to determine the microstructures at the interface and mechanical properties of an explosion welding AISI 304 stainless steel and AISI 1010 carbon steel. For the drawing forming process and the dissimilar welding of the spherical cap, a stamp was used, where after forming, the edge and its curvature were selected as the analysis area. With SOLIDWORD software, the occurrence of deformation and stresses during the process was established. It was determined that the metallurgical union is achieved with a wavy interface, which differs from its formation depending on the distance at which the detonation occurs, which favors metallurgical compaction, where the formation of equiaxial ferrite in the AISI 1010 originates. And austenite and martensite in AISI 304, but with smaller grain sizes as a result the expansive shock wave, as well as the presence of carbides of the M7C3 or Cr23C6 type. The determined hardness variation of 300 HV for the first and 450 HV in the second is due to the stacking of the grains due to plastic deformation. The greatest deformations and stresses in the spherical cap occur in the lower radius (bottom), which expand to the wall of the stamp. [ABSTRACT FROM AUTHOR]

The present article deals with the wear of the balls used for the grinding of the clinker in the processes of obtaining cement. Three specimens of different steel were made: one of steel AISI 4140, with which balls are forged for the milling process; another 70XL steel (70 XL) with normalized, tempered and tempered thermal treatments; and the third, of equal material that the second but without treatment. For the metallographic observation the samples were made with dimensions of 10 mm in diameter and 8 mm in thickness, revealing for AISI 4140 steel a structure of martensitic type with some presence of acicular ferrite. For the 70XL steel without heat treatment the presence of ferrite and cementite was observed, while the steel 70XL with heat treatment showed in the limits of free cementite grain in a pearly matrix, which resulted in a higher hardness (up to HRC 59, 8) and lower gravimetric wear compared to other materials. Therefore it is recommended as the most suitable for the manufacture of balls for grinding minerals 70XL steel with heat treatment. [ABSTRACT FROM AUTHOR]

The objective of the work was to determine the metallurgical components of the HK 40 alloy used in sweeping arm teeth after the casting process. Nine teeth were selected, which were cut into different parts according to their geometric shape, of which three had their microstructural behavior, grain size, percentage of carbides, hardness and porosity carried out. It was determined that, after casting, they present austenite, ferrite and carbide phases of the Cr23C6 type, but with variations in grain size with numbers of 3.5 and 5 respectively, associated with the solidification process. On the other hand, at a temperature of 715.55 ºC, corresponding to that of the solid for the teeth, there are pores with a cavity of 26.57 µm, where their presence is attributable to the geometric shape of the piece. The determined hardness maintains the same tendency in each one, so this property, although chromium carbides exist, should not cause them to break. [ABSTRACT FROM AUTHOR]

It is paper have the objective to establish the behaviour microstructure of an union welded dissimilar in an alloy HK 40 and the cast iron 24, which is carried out in team that you lend services in the industry of the nickel and that for the characteristics of the union, they arise in the same cracking problem. He was carried out a chemical characterization of both alloys, then for the process of automated got ready a total of nine samples, those that were welding for process shield for electric arch (SMAW), the electrodes lined employees were the E 312 - 16, the UTP 65 and the Castell Xiron 244, being demonstrated in the analysis microstructure and in the diagram of Schaeffler that the disposition of the union with the electrode E 312 - 16 cause the appearance of structure inter dendrite with origin to the white foundry, being more available the union with the electrode UTP 65. He was carried out the micro hardness analysis in each union. [ABSTRACT FROM AUTHOR]

This work presents a metallographic characterization of austenitic stainless steel AISI 321, which is the material of construction used in the pipe of the lateritic mineral screw conveyors operating in the nickel industries using Caron technology. A fractography was carried out by using macro and micro-analysis techniques; which allowed analyzing the fractures caused by spreading of cracks due to prolonged exposure to high temperatures (650-700 °C) in addition to manufacturing defects. Samples of steel used in the process were taken to determine the chemical composition and an optical microscopy was conducted to identify the intrinsic characteristics and the morphology of the cracks causing the rupture. Destructive testing trials were completed at the conveyor's operating temperatures. A microhardness testing for metal matrix and carbide hard compounds indicated high values for the latter elements, which act as stress concentrators when forming conglomerates. [ABSTRACT FROM AUTHOR]

This article exposes the effect bubbles implosion causes on buckets on the liquor from carbonate-ammonia leaching (mixture of water, ammonia and particles in suspension) of ferronickel lateritic ores. Based on the previous results that establish a relationship between the bubbles' size and the ammonia concentration of the liquor, the microstructure of a Hastelloy C 276 steel blade affected by cavitation was analyzed. It was also obtained that affectations are smaller in the initial area of the bucket than the distal parts, where complete perforations can be produced in the metal, what is associated to the fact that bubbles develop a great size at a concentration of 34% of ammonia in the liquor and implode at the exit of the bucket producing more intense pressure waves than those generated by the bubbles formed at 27% and that implode in the initial zone. It is concluded that the microstructural changes in the bucket material are closely related to the concentration of ammonia in the liquor making pitting, cracks, and cavities larger when the concentration of ammonia is maximum (34%). [ABSTRACT FROM AUTHOR]

In companies producing nickel with Caron technology, the wear and tear on the impellers of the turbo-rods causes the shortening of the life of these equipment. The objective of the present work is to evaluate, under abrasion conditions of the reduced ore subjected to leaching in the Caron process, the wear resistance of AISI 420 high strength steel, in order to use it as a substitute for steel X27H20 (ASTM 314), of which these impellers are currently manufactured. To determine the abrasion resistance, in the melt state, and to compare the results, samples of AISI 420 steel were subjected to a tempering and tempering heat treatment, then subjected to wear tests, using the gravimetric method, with times of permanence of one hour, previous taking of the weight. The results show that although there is a slight difference between the hardness of the material in the melt state and with heat treatment, the weight loss has very low values, so that it is concluded that the material proposed and evaluated meets the requirements established, and exhibits behavior consistent with the manufacturer's requirements. [ABSTRACT FROM AUTHOR]

In this article, we study various solution schemes reported in the literature, which deal with the problem of irregular parts distribution on flat surfaces with two-dimensional nesting. Different solution schemes were analyzed, which they consider to be the real geometry of the part, during the evaluation and positioning them on the surface to be cut, ensuring the best use of the material. The proposed scheme is characterized by a graphic treatment of the pieces that can accelerate the process of recognition and evaluation of options coupling between them, as well as the creation of cluster populations growing to its final location on the surface to be cut. In the generation of populations of possible solutions, using an algorithm based on the method of integration variables, in addition is made comparing the results obtained by the proposed method with other results generated by procedures developed by different authors, achieving improved use. [ABSTRACT FROM AUTHOR]

The objective of this investigation is to establish the behaviour of the microstructure of dissimilar joints made of titanium with AISI 1020, 1066 and 1008 steels through explosion welding. A detonation velocity of 2 800 m/s, a charge radius of 0,345 kg and a collision velocity of 1196, 16 m/s with an explosive volume of 600 cm3 and a density of 1,15 g/cm3 were considered. The microstructures obtained were composed of equiaxed ferrite grains, very fine grains of troostitic type and coarse grains with ferrite grid. Fine and aligned grains of ferrite type are observed in the casted area of both base materials. The metal hardness experienced an increase in samples from 120 HV AISI 1008 steel up to 250 HV for AISI 1066 steel. The AISI 1020 steel joint with titanium has an line shaped interface unlike the AISI 1008 steels with 4063 forms waves with uniform width, which provides a higher mechanical resistance associated with the ductility of the AISI 1008 steel. [ABSTRACT FROM AUTHOR]

Cast irons constitute a group of most versatile materials with multiple industrial applications from the range of mechanical properties that offer. In this study, an experimental analysis of the effects caused by the use of vibrating pouring into the matrix and hardness of ductile irons is exposed. As a result of applying different vibration frequencies, a direct relationship between the vibration frequency and the hardness obtained is demonstrated further improvement is achieved in the spheroidizing. All this leads to a reduction in rejection rates and a decrease in mass nodulizant. [ABSTRACT FROM AUTHOR]