Strength characteristics of the materials obtained by hot forging of porous powder preforms. II. Effect of heat treatment on the tensile and shear strength and the compressive yield stress

Conclusions Annealing of the powder metallurgy steels leads to a reduction in the values of the parameters _t, , and ^c _0.2. During this process, they become lower than those of the hot rolled (worked) products. However, after annealing, the stability of all the three characteristics increases. Quenching followed by a low-temperature tempering improves the parameters _t, , and ^c _0.2, but in this case, brittleness of the material increases. With increasing tempering temperature, all the three parameters decrease and at 600°C, they are virtually at the same level as that obtained after annealing at this temperature.The change in the yield stress after quenching and tempering or after annealing determines to a significant extent the nature (whether brittle or ductile) of shear fracture.Translated from Poroshkovaya Metallurgiya, No. 4(280), pp. 73–75, April, 1986.     

Effect of composition and porosity on the hardenability and hardness penetration of structural powder steels

Conclusions The effect of porosity ( > 10%) on the hardenability of the powder steels is stronger than the effect of carbon content. The role of these factors changes with the reduction of porosity ( < 10%) and the carbon content exerts a stronger effect on the hardenability of the steel. After hot pressing, the hardenability of the powder steels approaches the hard-enability of the dense steels of a similar chemical composition.The hardenability of the alloy powder steels at a constant carbon content and porosity is independent of the degree of alloying of the steel.The strength of the effect of complex alloying on the hardness penetration of the powder steels increases with decreasing porosity, especially after hot pressing and annealing as a result of the more efficient homogenizing of the structure with respect to carbon and alloying elements.Translated from Poroshkovaya Metallurgiya, No. 1(277), pp. 82–86, January, 1986.     

Development of tungsten-carbide-base corrosion-resistant composite materials with a binder of PKh8N15 stainless steel

Conclusions The bend strength of VNS20 and VNS32 composites is determined by the quantity of ₁phase and depends little upon the content of binder (PKhl8N15 steel). The hardness, on the other hand, depends substantially upon both the ₁-phase content and upon the quantity of binder.The VNS20 and VNS32 composites sintered at the temperatures of the start of formation of the liquid phase in the tungsten carbide—PKhl8N15 steel system, when compaction is completed and the rate of formation of ₁-phase is still insignificant, have the optimum properties.With a satisfactory level of physicomechanical properties, the VNS20 and VNS32 composites show high corrosion resistance in a medium of nitrine with additions of nitric acid.An increase in the strength of VNS type composites may be obtained by reducing the diffusion reaction of tungsten carbide with stainless steel.Translated from Poroshkovaya Metallurgiya, No. 5(281), pp. 69–75, May, 1986.     

The effect of the amount of-phase on the vibration absorbing properties of powdered iron-manganese alloy

Conclusions A correlation was established between the content of -phase in the structure of the alloy Fe-Mn and its vibration absorbing properties. An increase of the amount of -martensite to 50–60% leads to an improvement of the vibration absorbing properties; when the content of -phase is further increased, the vibration absorbing properties deteriorate. To ensure maximal vibration absorption, the alloy has to contain 50–60% -phase. It was also cleared up what effect some heat treatment parameters have on the amount of -phase contained in the alloy.Translated from Poroshkovaya Metallurgiya, No. 12(288), pp. 52–55, December, 1986.