Steel Swarf Research Articles

Effects of niobium carbide additions upon the production and properties of sintered high-speed steel

1. A study was made of the comminution to powder, in a rotary ball mill, of R18 high-speed steel swarf containing niobium carbide additions and of the subsequent processing of the resultant composite powders to dense blanks. 2. Niobium carbide was found to intensify the swarf comminution process: In powder milled for 48 h, the presence of 5 vol.% NbC increased the yield of the −0.25-mm fraction from 46 to 81% and that of the finest (−0.04-mm) fraction from 35 to 45.5%. At the same time, the mean particle size decreased from 0.31 to 0.18 mm. 3. A study was made of the pressing and sintering of the high-speed steel powder with niobium carbide additions. Strong compacts with a relative density of 70–73% were produced by pressing the powder, with a rubber addition, under a pressure of 8–10 tons/cm2. 4. Sintering, in the absence of a liquid phase, for 60 min at 1250°C in very dry hydrogen was found to yield blanks with a relative density of more than 95%. The blanks were characterized by a fine-grained structure and a mean carbide grain size of 1.5–2μ. 5. The addition of niobium carbide affected the size of the austenitic grain, reducing it from 18μ at 1 vol.% NbC to 7μ at 5 vol.% NbC. 6. The introduction of niobium carbide raised the hardness of the sintered steel, from 59 HRC (without NbC) to 65 HRC at a NbC content of 5 vol.%.

Use of briquests of ShKh15 steel swarf in smelting stainless steel

Use of briquests of ShKh15 steel swarf in smelting stainless steel

Processing of W-Cr-V-Mo tool steel swarf by the powder metallurgy technique

1. In an investigation of the sintering process of compacts from powders obtained by grinding W-Cr-V-Mo high-speed steel (R18) swarf, the effect of the following factors promoting intense densification was determined and elucidated:

Hardenability of porous ShKh-15 steel

The investigation has established that the hardenability of porous specimens obtained by pressing and sintering ShKh-15 steel powder decreases with increasing porosity. For porous specimens prepared by the dynamic hot pressing of ShKh-15 steel swarf, the hardenability increases with rising porosity. This relationship is attributed, on the basis of metallographic investigations, to the influence of the structural factor.

Auxiliary Equipment

The ‘Air‐O‐FIow’ industrial vacuum cleaner was introduced recently when it was demonstrated in a wide range of cleaning applications. The unit works on the Venturi principle from a compressed air line at or above the standard pressure of 80 lb./sq. in. and will ‘inhale’ a large variety of ‘foreign bodies’—including broken glass, nuts and bolts, steel swarf and liquids. The unit has three interchangeable nozzles and a mobile stand, overall height is 23½ in. with a diameter of 11 in. and weighs 14½ lb. empty. The National Gas Turbines Establishment employs the ‘Air‐O‐Flow’ unit for the transfer of engineering machine suds and Handley Page, who were supplied with the equipment by the Royal Air Force, use it for extracting fuel from the tanks of the Victor.