Re: Calibration Block for Duplex In Reply to ali at 12:16 Feb-09-2010 (Opening).
You are correct to assume that the ultrasonic velocities between Type 304 Stainless Steel and Duplex Stainless Steel are different. If you require a NIST traceable step block, PH Tool stocks two versions in Duplex Alloy 2205. The standard ASTM E797 5-Step, Inch version (.100, .200, .300, .400, and .500 inch) and the 5-Step, Metric 5B version (2, 4, 6, 8, and 10mm). If you do not require a formal test block, Mr. S. V. Swamy's suggestion of using the actual part for thickness calibration may suffice.