ASTM A503-15 (2020) pdf free.Standard Specification for Ultrasonic Examination of Forged Crankshafts.
The crankshaft should be examined after heat treatment,but before machining geometric features such as chamfers andoil holes that could interfere with ultrasonic examination.8.2 Unless otherwise specified by the purchase order,thescanned surfaces shall have a maximum surface roughness of250 uin. [6.35 um] where the definition for surface finish is asper Specification A788/A788M.
The crankshaft shall be scanned as shown in Fig.
For acceptance purposes，the crankshaft shall bedivided into three zones as shown in Fig.1.Because of crankshaft geometry, particularly for CGFcrankshafts, the ultrasonic examination shall be carried out tothe maximum extent possible.
Solid Forged Crankshafts:In Zone 1, indications equal to or greater than 20 % ofthe back reflection as established in 7.1 shall be cause forrejection.
Indications in Zone 2 equal to or greater than 50 % ofthe back reflection shall be cause for rejection.
Indications in Zone 3 equal to or greater than 100 % ofthe back reflection shall be cause for rejection.
Loss of back reflection in excess of 50 % in any zone,and not caused by geometric configuration, shall be recorded interms of size and location. Normally this condition shall because for rejection, but it may be referred to the purchaser fordisposition.
Continuous Grain Flow Crankshafts (CGF): Ultrasonic indications detected in CGF crankshaftsshall be evaluated in accordance with Fig. 3. Indications thatexceed the appropriate zone curve are cause for rejection.9.3.2 Loss of back reflection in excess of 50 % in any zone,and not attributable to geometric configuration shall be recorded in terms of percentage loss and location. Normally thiscondition shall be cause for rejection, but it may be referred tothe purchaser for disposition.
A distance amplitude correction (DAC) curve shall beused to provide compensation for signal attenuation.
Two or more reference specimens of incrementallengths shall be used to establish the DAC curve.
The reference blocks shall be manufactured in accor-dance with Practice E428.
The DAC is established by placing the search unit onthe reference block with the shortest distance to the test holeand adjusting the gain control to secure a signal response of100 % full screen.The signal peak is marked on the screen.ASTM A503 pdf download.