I have been asked to forge a grappling hook for a local marine fire fighter for the purpose of throwing at a small boat that is on fire to pull it in to range to hit with a fire hose. It is a vague description but not important none the less. I have forged the grappling hook itself by splitting sucker rod (courtesy of richard thibeu) into 4 hooks and forging an eye on of the other end.

My main question is this... What is a good color to temper the hooks to for maximum strength? I have yet to harden or temper the whole piece. I have minimal experience with forging with sucker rod. Thank you in advance.

John

A IForgeIron search for sucker rod gives 119 returns. The following look promising.

sucker rod carbon content?
BP0020 Spark Testing
BP0002 Junk Yard and Rail Road Steels toward the bottom

Remember that the color you temper to will vary based on the carbon content of the steel used. High carbon tempered to a say dark blue might be equal to a medium carbon tempered to a light blue. Sounds like you may need to experiment. What is the likely load he will be applying? If you tempered to a purple will it bend given the load? If yes temper to a lighter color if no stay where you are.

The load is minimal. Maybe 60lbs max. Thank you very much doug.