ASTM B391-03 pdf free.Standard Specification for Niobium and Niobium Alloy Ingots.
The manufacturer shall use care to have each lot of ingotmaterial as uniform in quality as possible.When specified,the ingots shall be conditioned on thesurface to standards agreed upon between the manufacturer andthe purchaser.
Subsequent fabrication will be permitted.The differencebetween the maximum and minimum radius of the conditionedingot shall not exceed 20 % of the maximum radius. Lands,grooves, and local depressions shall be blended to a maximumangle of 30° to the axis of the ingot.
Each ingot shall be tested for soundness by nondestruc-tive test methods,such as dye penetrant or ultrasonic tests.Methods and acceptance standards shall be as mutually agreedupon between the purchaser and the manufacturer.
Defects in the ingots that exceed the acceptance standards shall be removed by cropping or surface conditioning,
whichever is appropriate. The manufacturer shall be permittedto remove surface imperfections provided that after such
removal the requirements of conditioning are met (8.2).The ingots shall be free of imperfections that would bedeemed injurious by the standards of acceptability agreed uponbetween the purchaser and the manufacturer.Care shall be exercised to ensure that the sampleselected for testing is representative of the material and that itis not contaminated by the sampling procedure. If there is any question relating to the sampling techniques or to the analysisthereof，the methods for sampling and analysis shall be asagreed upon between the purchaser and the manufacturer.10. Number of ‘Tests and RetestsIf any sample or specimen exhibits obvious surfacecontamination or improper preparation，disqualifying it as atruly representative sample, it shall be discarded and a newsample or specimen substituted. In case of failure,retest two additional specimens. Ifboth specimens conform to this specification,discard theoriginal values and consider the material acceptable; otherwisethe ingot shall be rejected or reworked and retested.
Take individual hardness readings on the ingot side-wall along the full length of the ingot to within 5 in. of eachend. Spacing between indentations shall not exceed two ingotdiamefers.For the purpose of determining compliance with thespecified limits for requirements of the properties listed in thefollowing tables, an observed value or a calculated value shallbe rounded as indicated in accordance with the roundingmethod of Practice E 29. Determine Brinell hardness by Test Method E 10,except，using a load of 4.9 kN with a 10-mm ball.Material that fails to conform to the requirements ofthis specification may be rejected. Rejection shall be reportedto the producer or supplier promptly and in writing. ASTM B391 pdf download.