S355- anneal to lower yield?

[acrmnsm]

Hi We have some S355H and we want to carry out some physical testing, we cannot get S275H in the size we require in the timescales required. Do you think we could anneal S355 to achieve a lower yield? So we are planning to cut some sameples from our current hollow section, and anneal them, then tensile test to see what yield and elongation we get.

 

[metengr]

Why in the world would you want to reduce the yield strength of the S355H structural steel? Most engineers worry about strength margin in design. I doubt that you will achieve the S275H strength properties, instead, I would suspect the material will exhibit some reduction with grain growth and significant anisotropic notch toughness behavior.

 

[acrmnsm]

I know, suprising isn't it. let em assure you that there is a good reason that commercial confidentiality will not let me explain.
I am not rying to create S275, I would prefer S275 but we cannot get it in the sizes required. So we need to try and reduce the yield of the S355 we have.
Could you define more clearly what you mean by "anisotropic notch toughness behaviour"
The material is in hollow form -tubes, it is anisotropic already. We get 20% variation in yield and smaller variations in strain hardening in the longitudinal and transverse anyway. We get wide variation in charpy's anyway even in samples from the same material.

 

[metengr]

My concern would be excessive or abnormal grain growth and even wider variability in properties because the higher strength material might have been originally produced by TM treatment. As you know, yield strength and notch toughness are significantly influenced by grain size.