[en] Short note

[en] A method of surface hardening metal by heating and subsequent rapid cooling is claimed. The heating is effected by generating a beam of electrons and directing and focussing the beam onto the surface of the metal. Apparatus is also claimed. It comprises a vacuum chamber, means for evacuating the chamber, an electron gun for generating, accelerating and focussing a beam of electrons and a computer for controlling the electron beam gun parameters

[en] Surface hardening by electron beams permits partial hardening of workpieces and tools with high-speed heating-up and slow-speed cooling-down. Electron beam welding machines used in the GDR at present can be adapted to this purpose without instrumental effort. Two different modes of operation have been applied, especially for two-dimensional hardening of shaft seats. Hardness obtained, hardening depth achieved, and beam parameters applied are discussed taking into account technological requirements and limits

[en] This work aims to characterize the 36 NiCrMo 6 steel in monotic traction. The tested samples were subjected to mechanical surface treatment (MST) by diamond ball burnishing. This process allow it possible to modify the physical and geometrical properties of the material. The stress-strain diagram obtained were processed and digitalised. The hardening domain was modelled and rational curves were established, taking into account the stresses triaxiality. Thus, the work hardening exponent of material considered was evaluated. The effect of ball burnishing on this exponent has studied in proceeding a comparative manner between burnished and machined surface. The results obtained show that by applying the optimal parameters for burnishing, the work hardening exponent of pre-machined surface layer can be increased by 10%, where n_B = 0.407 (n_T = 0.312 machined surface). (paper)

[en] Nuclear energy production advances are essential to meeting projected world energy needs. Safe, continuous plant operation will guarantee the generation of this energy. Within nuclear power plants, valve service is critical to daily operation and maintenance and plant emergency controls. To increase nuclear stainless steel valve quality and reliability, the Westinghouse Electro-mechanical Division has selected manual plasma transferred arc hardfacing for three critical wear applications - backseat ring bore, gate wedge guide surface, and gate disc guide lug. The manual plasma process was initially compared with these alternatives - gas tungsten arc, shielded metal arc, and oxy-acetylene hardfacing. The considerations influencing process selection were: customer and engineering design requirements, materials, manufacturability, and relative costs. Process selection and implementation elements and current production controls have accomplished superior finished component quality. (Author)

[en] Study of surface treatment of steels by boron trifluoride with sand to obtain a hard Fe₂B coating

[en] In this colloquium are reviewed the development of hard materials and hardening of nuclear components undergoing friction to improve wear resistance for example primary coolant circuit vanes and particularly the development of nickel base alloys as a substitute to cobalt base alloys

[en] The use of the electron beam process for surface remelting of drop-forging dies is described. Use of the method on a production basis gave unsatisfactory results. The cause of this is shown and possible ways of overcoming the difficulties encountered in surface remelting by the electron beam process are presented. (author)

[en] Ion implantation, formerly used as a means of fabricating semi-conductor devices, is being developed as a new method of improving the durability of material surfaces. This follows several years of R and D by scientists and engineers at the Nuclear Physics Division of the Atomic Energy Research Establishment, Harwell, England. Here, the problems of applying an ion implantation to provide greater resistance to wear and corrosion of production tools and equipment, have been largely solved. In fact, the technique has been licensed for the commerical manufacture of ion implantation machines

[en] Laser Induced Breakdown Spectroscopy (LIBS) is a well-known spectrochemical elemental analysis technique, which has been exploited to determine the surface hardness of a metallic alloy such as titanium-based alloy samples (Ti-6Al-4V). It is shown that there is a direct proportionality relation between the ionic to atomic spectral lines intensity ratios and the surface hardness values measured mechanically via Vickers hardness test for the Ti-based alloy samples. In the present study, the proportionality relation has been demonstrated adopting different ionic and atomic spectral lines ratios from the corresponding LIBS spectra. Additionally, the laser induced plasma parameters, namely the electron density and the plasma excitation temperature have been estimated as a function of the surface hardness of the adopted alloy samples. The obtained direct proportionality between the plasma temperature and the samples surface hardness has been interpreted in view of the increased collisions in the plasma plume due to the strong repulsive forces for harder targets. On the other hand, such high repulsive force leads to fast expansion of the laser induced plasma plume and consequently to a decrease in the electron number density in agreement with the inverse proportionality obtained between the surface hardness and the electron density. The results obtained in the present work demonstrate the potential of using LIBS in metallurgical and industrial applications for the direct determination of different alloys surface hardness, saving time and cost adopted by conventional techniques