High tensile steel 45ton.

[derek]

Would some knowledgeable person out there answer the following questions about high tensile steel:
When heated to bend, or when welded, is the strength or properties of the steel altered? What is the carbon content of high tensile steel, and is it subject to any heat treatment at manufacture? Thanks Derek.

 

[wmg73141]

The most common version of a 45 ton tensile steel, (in old money), is EN24t a 1½% nickel/chrome/molybdenum alloy, the current designation is 817M40.

It is a versatile material which can be heat treated for a wide range of properties right up to 100 tons tensile strength.

I do not think it would be an easy material to weld successfully and would probably require very controlled conditions.

It can however be forged from a temperature of 1150°C if the shape you require makes that an option.

To regain the properties following operations involving heat will require annealing from a minimum temperature of 850°C and cooling in air.

To harden heat to 830/850°C and quench in oil followed by tempering at 200/250°C and cooling in air for the 100 ton condition or up to 550/660°C for greater toughness.

 

[wmg73141]

Gawd! I really must be gettin’ old! --- If all else fails read the question properly!

So to tidy up a bit:

Bending is effectively forging so working temperature should be as above. (1150°C)

EN24t was sold in the heat-treated state; in that condition its properties were that of a tough material but still quite easily machined. I’d guess that it was available in the fully annealed state but I never had occasion to buy it in that condition.

Following any bending/welding I would recommend an annealing cycle to refine the grain before hardening and tempering to the desired final condition.

Composition:

C = 0∙35/0∙45% : Si = 0∙1/0∙35% : Mn = 0∙45/0∙7% : Ni = 0∙1.3/1.8% : Cr = 0∙9/1∙4% : Mo = 0∙2/0∙35%

Now, wadda I miss?

 

[clevtrev]

Gawd! I really must be gettin’ old! --- If all else fails read the question properly!

So to tidy up a bit:

Bending is effectively forging so working temperature should be as above. (1150°C)

EN24t was sold in the heat-treated state; in that condition its properties were that of a tough material but still quite easily machined. I’d guess that it was available in the fully annealed state but I never had occasion to buy it in that condition.

Following any bending/welding I would recommend an annealing cycle to refine the grain before hardening and tempering to the desired final condition.

Composition:

C = 0∙35/0∙45% : Si = 0∙1/0∙35% : Mn = 0∙45/0∙7% : Ni = 0∙1.3/1.8% : Cr = 0∙9/1∙4% : Mo = 0∙2/0∙35%

Now, wadda I miss?

The T indicates it`s the heat treated form. Otherwise it`s just plain EN24.