ASTM B600-91 pdf free.Standard Guide for Descaling and Cleaning Titanium and Titanium Alloy Surfaces.
It is recommended that heattreatable alpha beta andbeta alloys in the solutiontreated condition that have beenprocessed at temperatures above 1100°F (593°C), with graphitic and molybdenum disulfide lubricant residues mixed withthe heatdeveloped scale, be conditioned in a molten alkalinebased salt bath operating at 400°F(204°C).After conditioning,the part may be pickled in accordance with the treatmentdescribed in 4.3.2.
Abrasive methods such as wheel or belt grinding,segmented flapper wheels，and grit or shot blasting，whenavailable, may be used when surface configuration is such thatthe scaled areas are readily accessible.
After salt bath conditioning and water rinse，thetitanium or titanium alloy may be immersed in a sulfuric acidsolution to remove the converted scale product. It is recommended that the acid solution be maintained at 150°F (66°C)and a concentration of 10 to 40 volume % of sulfuric acid (95 % solution by weight). Final brightening may be accom-plished by a short immersion in the acid solution of 4.3.2.4.3.2 Material that has been mechanically abraded in accor-dance with 3.1 or chemically conditioned in accordance with4.2.1,4.2.2,or 4.2.3 may be finish cleaned by immersion in anacid solution composed of 10 to 30 volume % (150 to 450 g/L)of nitric acid (70 %) and 1 to 3 volume % (12 to 36 g/L) ofhydrofluoric acid (60 % at 120°F(49°C)), maintaining a ratioof 10 parts nitric acid to 1 part hydrofluoric acid.
Visual inspection of material cleaned in accordance withthis guide should show no evidence of paint, oil, grease, glass,graphite lubricant，scale，abrasive,iron,or other forms ofcontamination.
Hydrogen absorption during the cleaning process shouldbe minimized and well within tolerable limits if the proceduresoutlined are followed. Periodic monitoring of the cleaningsystem can be accomplished by processing samples of knownhydrogen content through the complete system followed bychemical analyses.A hydrogen increase greater than 20 ppmover the original product analyses may be cause for replacingthe acids or adjusting the composition to reduce the extent ofhydrogen pickup.
Additional evaluation of product cleanliness may beobtained by chemical milling of an expendable sample testpiece.It is recommended that approximately 0.001 to 0.002 in.(0.025 to 0.05 mm) shall be removed from each surface.Afterchemical milling, the surface should be uniformly smooth andbright with the absence of peaks indicative of residual scale orcontamination.ASTM B600 pdf download.