Papers by Keyword: Hadfield Steel

Abstract: Hadfield steel is widely used in the manufacture of machines and mechanisms operating in harsh conditions. When machining Hadfield steel parts, problems are due to the strain hardening. The article studies the influence of cutting modes on steel hardness, tool thrust and surface roughness when milling Hadfield steel using cutters with replaceable inserts. The experiments were conducted on a milling machining center using high-productivity cutting tools. The optical roughness measuring method was applied. Hardness was measured with a portable hardness tester before and after milling. The article describes experimental results that show the dependence of the output machining parameters on the cutting speed and feed per tooth. The influence of cutting data on tool life in a finish milling operation was identified. The results will help to improve the quality and productivity and increase the tool life in roughing and finishing Hadfield steel parts.

Abstract: The results of tests for resistance to abrasive wear on highly abrasive hard rock white electrocorundum are presented. The main material of fast-wearing elements of mining and processing equipment-110G13L steel (Gadfield steel) in comparison with other 9 grades of steel and cast iron, including specially developed wear-resistant foreign steels such as Hardox and Miiluks, is analyzed. The studies were carried out using an experimental stand for studying the material wearing process. On the stand the sample was fixed in a holding device and, after being brought into contact with the abrasive, it was rotated under a constant load. As a result of the experiments, it was confirmed that the order of placement of the tested materials in terms of increasing wear resistance coincides with their placement in terms of increasing hardness. At the same time, the wear resistance of the most resistant material – U8A steel after quenching – is about 4 times higher than this indicator for the least resistant components – low-carbon steel 25L, including gray and high-strength cast iron SCH21, VCH35. The wear resistance of 110G13L steel, as well as 65G, U8 steels in the hardened state, is from 1.5 to 2 times higher than that of foreign steels M400, H450, M500, H500. The results of the conducted studies allow us to evaluate the analyzed materials on the basis of their wear resistance and hardness indicators on the feasibility of using them in the manufacture of fast-wearing parts of mining equipment. Based on the research data, it seems promising to develop new ways to increase the wear resistance of domestic steel, including 110G13L steel traditionally used in mining.

Abstract: In this contribution, the preparation of metallographic sections and characterization of the microstructure of manganese Hadfield steels are discussed. The purpose of this paper is to provide information relevant to microstructural characterization of these steels. This type of steel is characterized by high resistance to abrasive wear, which is provided by surface strengthening through strain-induced martensitic transformation. Strengthening complicates the preparation of metallographic sections because the final microstructure can be influenced by the process and it can be eventually misinterpreted. Great attention must be paid to the choice of the etchant and the etching procedure. This contribution describes the entire metallographic characterization procedure, including the evaluation of grain size, micro-cleanness and presence of carbides on grain boundaries. It provides information for manufacturers and those, whose process and examine Hadfield steels with respect to their processing routes, wear resistance, non-magnetic properties and other aspects.

Abstract: Ladle treatment of molten Hadfield steel considers as the new effective technique for producing Hadfield steel instead of conventional heat treatment process. New eutectic is formed as a result of the ladle treatment process. In this research, the strain-hardening property of the four grades of Hadfield steel containing granular new eutectic phase has been investigated, and compared with the conventional Hadfield steel. Optical and scanning electron microscope reveal that slip bands fractions vary through the five grades of steel as a result of deformation. XRD observation refers to the austenite phase is still the dominant phase through the whole five grades of steel after deformation. The results of the compression and hardness tests clarify that the new granular eutectic phase has a significant effect on the strain-hardening behavior, austenite stability. The nodularity of new eutectic phase is a considerable parameter in the function of yield strength, and hardness increment as well.

Abstract: The operational degradation of surface layers due to a rolling contact process was simulated for Hadfield steel by a special testing rig. A specific limited state based on cumulative depletion of plasticity was achieved.Precise evaluation of the surface layer's mechanical parameters is necessary for a service life prediction. Very low depth of localized dislocation hardening process doesn ́t allow the standard mechanical testing. The comparative instrumented indentation tests using Vickers and cylindrical indenter were used for evaluation of defined stage of surface degradation process. The intensity and reach of deformation hardening are partially limiting for particular methodology. The yield stress of surface layers was estimated according to an analytical model of uniaxial vs. indentation plastic flow ratio.

Abstract: It ́s known that the hardness of the metals changes during the cold working. In this paper we analyzed the Hadfield steel hardness in effect of the explosive treatment. We wanted to find a relationship between the detonation velocity and the hardening in case of two different explosives. Also we wanted to find a relationship between the available hardness and the direct and indirect explosive hardening technology parameters. The explosion technology can be useful in case of optimal explosion parameters. The calculation of these parameters need a many experiments. By this work we want give assistance by our empirical results to find optimal hardening parameters.

Abstract: The process of explosive hardening of hadfield steel by a new flexible explosive was researched, and the change of hadfiled steel metallurgical structure was observed. The results show that: 1. Three times of explosive hardening by using 3mm explosive fill the demands of process (the surface hardness above 350HB,the hardening depth above 20mm,the sinkage below1.2mm and no crack in the surface);2. The hardness increment is decrease with explosive times increasing, and the hardness increment increase with the sinkage increasing;3.The internal hardness of the unprocessed hadfield steel is invariable basically, and the surface hardness is slightly fewer; the hardness of the hadfield steel hardening three times plunges largely when depth form 0mm to 2mm, and decreases gradually under 2mm.4.Grain refining, multiplication of dislocation and grain boundary sliding lead to the hardening of hadfield steel.

Abstract: In order to improve the effect of explosive hardening and reduce the production cost, the elastic-plastic explosive which consists of RDX, rubber, deterrent, antioxidant and plasticizer was prepared. The experiments including density testing, detonation performance, detonation velocity testing, impact sensitivity, and explosive hardening were carried out. The results show that the density of the elastic-plastic explosive is 1.46g/cm3, the detonation velocity is 6670m/s, the impact sensitivity is 28% and the elastic-plastic explosive can be detonated reliably by a detonator. The explosion hardening on Hadfield steel makes the hardness increased from 187HB to 362HB, which increases by 93.5%.

Abstract: The deformation twinning leads to a reduction of the coefficient of strain hardening, i.e. twinning plays an important role in deformation of steel. The contribution of twinning to the total deformation is significant (up to 1/3 of the overall deformation). The final effect of twinning on strain hardening rate depends on the number of factors introduced by the twinning itself in the process of sliding. Calculated Schmid factors for slip systems operating in the matrix and in the twin. The analysis of the twinning geometry in particular grains showed that twinning is primarily developed for systems with the highest Schmid factor. However, twinning was also observed with a minimum and even zero Schmid factor. The obtained results indicate the importance of the orientation of slip planes in the newly formed micro-twins and Schmid factors for twinning. The important role of crystallographic texture in the physics of strain hardening was also shown.

Abstract: The influence of the strain rate on the plastic deformation of the metals was significant during the high strain rate of loading. However, it was very difficult to obtain high strain rate data (≥ 104 s-1) by experimental techniques. Therefore, the finite element method and iterative method were employed in this study. Numerical simulation was used to characterise the deformation behavior of Hadfield steel during explosion treatment. Base on experimental data, a modified Johnson-Cook equation for Hadfield steel under various strain rate was fitted. The development of two field variables was quantified during explosion hardening: equivalent stress and strain rates.