The answer depends greatly on what specific acids are used, and what type of tooling is needed, e.g., hot-work, cold-work, plastic injection molding, etc. For the best resistance to acids, you should probably be looking at nickel-based alloys over tool steels, even if they are stainless alloys. Carpenter has several alloys that I would recommend investigating, including Pyrotool Alloy 7 and Pyrotool Alloy W. You can obtain more information using the following link:
click on Technical Information then Alloy Category then Tool and Die Steels then scroll to page 2 for the Pyrotool alloys. There are many other grades that may be suitable, again, depending on the final application, acid type and concentration, etc.
