Iron-based Powder Materials Research Articles

Chemical heat treatment of powder materials based on iron

Diffusion chromizing and boriding of iron-base powder materials SP30, SP90, and SP90D3 are studied. The growth kinetics for diffusion layers are determined depending on diffusion impregnation conditions, and material composition and porosity. Comparative bending and tensile strength tests as well as wear- and heat-resistance tests for materials after sintering by standard conditions or boriding and chromizing are performed. It is shown that the mechanical properties of materials after different types of processing are approximately the same whereas the wear and heat resistance after diffusion impregnation increase markedly. This makes it possible to conclude that a combination of sintering and boriding (or chromizing) is possible under the following conditions: boriding at 1000°C for 2–3 h; chromizing at 1100°C for 3–4 h.

Effect of methods of heating during sintering on the properties of iron-base powder materials

1. The use of induction instead of furnace heating during the sintering of powder materials of different compositions leads to the formation of a structure with no, or only a small quantity of, excess carbide phase. 2. Induction heating improves the sintering of powder materials, as shown by a decrease in the proportion of intergranular fracture in the fractured surface of rings. 3. The highest level of strength and plasticity was obtained in rings sintered by induction heating, prepared from ultrapack and primary carbides.

Effect of porosity on microplastic deformation of iron base powder materials

By the method of subjecting beams of uniform strength to bending tests we measured the modulus of elasticity of sintered iron base materials in a broad interval of porosity (0–40%).

Cavitation resistance of iron-based powder materials

Cavitation resistance of iron-based powder materials

Binding processes in hot-stamped iron-base powder materials. III. Influence of segregation of impurities on binding processes

The surfaces of macro-, micro-, and submicropores of specimens of all groups are more strongly enriched with impurity elements than the interparticle boundaries.

Special features of the ductile-brittle transition in iron-based powder materials. II. Physicomechanical model of the ductile-brittle transition in cracking resistance tests

The presence of pores in the material leads to the redistribution of stresses in the material and to localization of strains in small volumes between the pores. The susceptibility to ductile failure increases with increasing porosity.

Special features of the ductile-brittle transition in iron-based powder materials. I. Mechanical characteristics of powder iron in the ductile-brittle transition temperature range

Special features of the ductile-brittle transition in iron-based powder materials. I. Mechanical characteristics of powder iron in the ductile-brittle transition temperature range

Carbonitriding of iron-base powder materials

To strengthen iron-base powder materials it is desirable to use a short carbonitriding operation.

Thermal stability of some metallic sulfides in sintered iron base materials

1. During the sintering of iron base powder materials containing various metallic Sulfides, the latter may undergo partial or complete decomposition. The initial temperature and degree of their decomposition depend upon their stability, the composition of the material being sintered, and the nature of the atmosphere used. 2. The presence of sulfides in sintered materials used as bearings operating in an air atmosphere results in the formation of wear-resistant films on their friction surfaces. The composition of the these films is influenced by the chemical transformations occurring during sintering and the nature of the interaction in the friction contact zone, involving the matrix material, the sulfur-containing addition, and the ambient atmosphere.