Does annealling change yield stress in steel

[coppa]

Does the process of annealing (at 950 deg c) or stress relieving (at 650 deg c) alter the yield stress of BS EN 10210 1993 S355 or s275 steel (sorry for the UK spec).

 

[Maui]

In general, the purpose of annealing is to soften the material so that it can be processed further. Annealing dramatically reduces the residual internal stresses that develop from hot working operations such as forging, rolling, stamping, etc. Because the material can be softened considerably by using an appropriate annealing cycle, both its tensile strength and yield strength are typically reduced. The amount that it is reduced by depends upon the material in question, the prior mechanical and thermal history, and the annealing cycle used.



Maui

 

[stanweld]

In addition to Maui, if you plan to anneal or temper these steels after purchase, you should require the mill/supplier to provide the tensile properties of the steel heats in the final heat treated condition.

 

[yn]

Dear Coppa and All,

Do you mean annealing or stress relieving of steel which have been previously pre-annealed?
I've experiences with stress relieving 1.00 mm strip steel of 200 MPa Yield strength through continuous annealing line at two types of cycle settings (FH at 550 deg C and CQ at 680 to 690 deg C). The temperature setting was achieved only at the first cycle...at 550 deg C.. and the result was the ductility of the product drop and the yield strength increased by around 70 MPa. Actually, I didn't expect this increase.
However, I'm still wondering what might happen in the steel that cause hardening due to this annealing. Highly appreciate if someone may answer it.

Regards,
Yenny

 

[priyasachin]

Priyasachin

Dear friend,

If the original material is in normalised condition the stress relievig at 650 may not change much. Also annealing at 950 will change it a little. But if the material is in 'control rolled condition' or what is popularly known as 'TMCP'steel, any of these treatments would change the properties considerably.
Regards,
MRCN