Since you imaged the entire drive, the start of the .img files will contain a partition table. What does fdisk -l hdd1.img say?
Edit: mdadm is capable of parsing Intel software RAID metadata including, supposedly, the latest versions where the array is a "container" with one or more logical drives that may use different RAID levels. I've never tried using mdadm on image files, though.
You could always write the image files back to a set of functioning drives and recover the data using the original motherboard/PC.
Last edited by Ser Olmy; 08-01-2013 at 04:40 PM.