Heat treatment of S30408+Q345R composite steel plates
Thread Content
The thickness of the S30408+Q345R composite plate is (3+34) mm. How should the specifications for heat treatment be stated?
First, meet the strength requirements! Do I also need to meet corrosion resistance requirements? Are it the cleaning requirements again?
Replace S30408 with S30403
If heat treatment is performed on stainless steel composite sheets, do not use 304 and 316; instead use 304L and 316L, as this will not increase costs.
It must meet the requirements for strength and corrosion resistance. ~Is 600℃ heat treatment okay?
Switch to the one with L. Has the corrosion resistance decreased after heat treatment?
Ensured through manufacturing and welding processes! Low-temperature annealing can be considered! Decision by the quality assurance engineer!
This post was last edited by scaaa on 2018-12-28 at 14:07; the layered material should be replaced with ultra-low carbon or titanium-containing stainless steel. The ultra-low carbon range is a sensitization temperature zone; it reduces the precipitation of high-chromium carbides (Cr23C6). When the chromium content drops below the threshold for corrosion resistance, chromium deficiency occurs at the grain boundaries, leading to intergranular corrosion, and in severe cases the material can turn into powder. Titanium-containing stainless steel is used because Ti preferentially combines with carbon to form TiC, thereby serving to sacrifice Ti to protect Cr.
The post-weld heat treatment of composite panels is intended to treat the base carbon steel or low-alloy steel; in any case, it must not affect the anti-corrosion properties, as that would go against the purpose of using composite panels. The low-temperature annealing mentioned by 7# is a good option :)
This post was last edited by INJQZ on 2018-12-28 at 15:13. The shell of the liquid ammonia buffer tank is made of Q345R, while the pipe connections are made of S30403. Is heat treatment required in this case? (Liquid ammonia stress corrosion; low-alloy steel requires heat treatment)
The sensitization temperature range for stainless steel is 400–850°C, which exactly includes the temperature for stress-relief heat treatment. Heat treatment definitely has an impact on intergranular corrosion. The medium is liquid ammonia; there is only stress corrosion, no intergranular corrosion. This allows for stress-relief heat treatment to be carried out. Is this approach correct?