Abstract
Technological investigations are further described in which practical blast cleaning of steel plate was simulated in the laboratory.
Removal of rust is fastest when blasting is perpendicular to the surface. The smaller grain size of abrasive leads to higher rates of cleaning. Work-hardening of the surface depends on grain size and extends much deeper than can be deduced from microscope observation of cross-section.
A discussion of the concept ‘properly cleaned surface’ leads to the conclusion that 100% clean is a fallacy and that for the moment the use of a magnifying glass is the only practical method of inspection.
From a few exploratory tests on the cleaning of welds the conclusion is justified that blasting perpendicular to the weld surface leads to the highest cleaning rates. Small grain sizes are to be preferred.
The velocity of abrasive grains in flight was determined by high-speed photograph. Values found were somewhat higher than the ones reported for centrifugal machines. Influence of air pressure and specific gravity of the abrasive could be demonstrated.
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