M2 highspeed steel is by far the most popular highspeed steel replacing T1 in most appliions because of its superior properties such as its bending strength, toughness and thermoplasticity—all of which are higher than T1 by 50%. Other Known Names: HS 652,, S600 Steel, E M2, REX M2 ®, SKH 51, P6M5, 66, M2 Tool Steel.