Hardening of a quick-speed steel tool through nitration process with nitrogen controlled potential

The study of the gas nitriding method, which allows obtaining high-quality diffuse layers in high-speed steel P6M5 on the basis of an internal nitrogen hardening zone with no brittle nitride zone, has been viewed. Research results of phase composition of nitrided steel with a change in the nitrogen potential of the atmosphere during dilution of ammonia are presented. Nitrided tool increased resistance during drilling constructional steel and titanium alloy, which is due to precipitation hardening treatment of the internal nitrogenization zone using tungsten nitrides, is given.

Влияние высоких давлений на формирование новых соединений в сплаве Al-=SUB=-86-=/SUB=-Ni-=SUB=-2-=/SUB=-Со-=SUB=-6-=/SUB=-Gd-=SUB=-6-=/SUB=--=SUP=--=SUP=-*-=/SUP=--=/SUP=-

The structure, elemental and phase composition of the eutectic alloy Al86Ni2Со6Gd6 (hereinafter referred to as at.%) During the solidification of the melt from 1500oC at a rate of 1000oC/s under high pressure of 3 and 7 GPa have been investigated by X-ray diffraction analysis and electron microscopy. Solidification of the melt under high pressure leads to a change in the phase composition of the alloy and the formation of an anomalously supersaturated solid solution of α-Al (Gd). At a pressure of 7 GPa, new phases were synthesized: Al3Gd * (like Al3U) containing Co and Ni, with a primitive cube structure (cP4/2) with a lattice parameter a = 4.285 ± 0.002 Angstrem and Al8Co4Gd * (like Al8Cr4Gd) with a tetragonal structure (tI26/1) with parameters a = 8.906 ± 0.003 Angstrem and c = 5.150 ± 0.003 Angstrem. The structure of all the samples obtained is homogeneous, dense, finely dispersed, without shrinkage cavities and pores. The average microhardness of the samples is high due to solid solution and precipitation hardening.

Mechanical Property Improvement in Dissimilar Friction Stir Welded Al5083/Al6061 Joints: Effects of Post-Weld Heat Treatment and Abnormal Grain Growth

The 5083 and 6061(T6) aluminum (Al) alloys are widely used in transportation industries and the development of structural designs because of their high toughness and high corrosion resistance. Friction stir welding (FSW) was performed to produce the dissimilar welded joint of Al5083-Al 6061(T6) under different welding parameters. However, softening behavior occurred in the friction stir welded (FSWed) samples because of grain coarsening or the dissolution of precipitation-hardening phases in the welding zone. Consequently, this research intended to investigate the effect of the post-weld heat treatment (PWHT) method on the mechanical property improvement of the dissimilar FSWed Al5083-Al6061(T6) and governing abnormal grain growth (AGG) through different welding parameters. The results showed PWHT enhanced the mechanical properties of dissimilar joints of Al5083-Al6061(T6). AGG was obtained in the microstructure of PWHTed joints, but appropriate PWHT could recover the dissolved precipitation-hardening particle in the heat-affected zone of the as-welded joint. Further, the tensile strength of the dissimilar joint increased from 181 MPa in the as-welded joint to 270 MPa in the PWHTed joint, showing 93% welding efficacy.

Optimization of a Solution Treatment in the Al-Cu-Mg-Ag Alloy via a Microstructural Investigation

We investigated the effect of solution temperature (Tsol. = 440–530 °C) on the mechanical properties of the Al–3.4Cu–0.34Mg–0.3Mn–0.17Ag alloy, finding that the investigated Al alloy showed the highest mechanical strength of σUTS = ~329 MPa at a Tsol. value of 470 °C. The microstructural investigation demonstrates that the mechanical properties for different Tsol. values stem from grain growth, precipitation hardening, and the formation of large particles at the grain boundaries. On the basis of Tsol. = 470 °C, the effect of each microstructural evolution is significantly different on the mechanical properties. In this study, the relationships between the microstructural evolution and the mechanical properties were investigated with respect to different values of Tsol.