This part of JB/T 10544 specifies the ultrasonic testing method and quality classification of ductile iron crankshafts. This section applies to ductile iron crankshafts with engine bores below 200mm. The basic principles such as ultrasonic testing methods and quality classification of ductile iron materials and workpieces specified in JB/T 10554.1 are applicable to this part of JB/T 10554.