PROPERTIES OF NEW SINTERED MOLYBDENUM STEELS MODIFIED WITH BORON

摘要

Sintered molybdenum steels have found wide application in automotive industry. The molybdenum contained in a sintered alloy steel increases its tensile strength, abrasion resistance and hardening capacity. An addition of boron to the sintered molybdenum alloys activates the sintering process and results in their considerable consolidation. Experiments carried out in 2002 referred to the manufacture of sintered molybdenum alloy steels containing 0.55 wt percent C and 0.85 wt percent, with an addition of 0.2 wt percent, 0.4 wt percent and 0.6 wt percent B. Molybdenum content was within a range from 1.5 wt percent to 5 wt percent, and carbon was introduced in a form of a graphite powder. The sintered molybdenum alloy steels were obtained by mixing powders of iron, molybdenum, graphite and boron, followed by pressing and sintering at 1200 deg C for 60 min, in the atmosphere of hydrogen. Mechanical properties and structure of the sintered molybdenum steels modified with boron were determined experimentally. Combined effect of molybdenum and boron on the properties and structure of the materials investigated has been analysed.