Can reheating of steel return back its mechanical strength? 1

[azri ismail]

Hi, my company manufacture LPG cylinders. As part of manufacturing standard requirement, all cylinders shall undergo Post Weld Heat Treatment (PWHT) after welding process. The steel material that we are using is JIS G1116 SG295, thickness 2.6 mm. My question is if we already did the PWHT at a high temperature for example 820 degree Celsius (and resulting in low tensile (330 N/mm2) and yield stress (222 N/mm2)values), can we perform another heat treatment at a different temperature and holding time to return back the mechanical strength values to within 390 N/mm2 for tensile and 300 N/mm2 for yield?

I would welcome your expert opinion in this matter. Thanks,

 

[Dhurjati Sen]

I do not think your facility has an annealing furnace.

Also, you need to check hardness and micro-structure of the wrongly PWHTed material. Only stress values are not enough.

DHURJATI SEN

 

[EdStainless]

How did you pick the PWHT temp? That sounds hot.
If you overheat them they are then scrap.

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P.E. Metallurgy, consulting work welcomed