First off, Martensitic is a Ultra-high Strength Steel (UHSS). I will throw a little automotive talk into my update today. Many automakers use the same platform to built different model for each of their different brands. General Motors has a platform that is used throughout all of their brands called the Lambda platform. The Lambda platform is used on the Saturn Outlook, GMC Acadia, Buick Enclave, Chevrolet Traverse, and the Cadillac SRX. General Motors uses Martensitic steel in the outer rocker panel and vehicle underbody on the Lambda body structure. Look at the image below and the yellow parts are Martensitic steel.
After some checking around, I found that the reinforcement for the B-pillar is made from DP 980 which, like Martensitic, is a UHSS. The reinforcement is welded to another reinforcement made from HSLA. If you have to cut the B-pillar of a Buick Enclave or other platform model be prepared for multiple layers of UHSS reinforcements.