Regarding the choice between 304 and 316?
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I would like to ask everyone: 1. If a bracket is submerged in water, how can one determine which material should be chosen to avoid corrosion and failure? For example, when it comes to the chlorine content in water, 304 can be used if that level is below a certain value, while 316 can be used if it’s above that value! 2. Regarding 304 or 316 steel, is it effective to use acid pickling and passivation paste only on the area around the weld to prevent corrosion? Thank you all!
304 can be used when the chloride ion concentration is no more than 25 mg/L; pickling and passivation are effective to a certain extent
304 steel can be used when the chloride ion concentration is no more than 25 mg/L; pickling and passivation do have a certain effect. How was this standard established? Is it possible to check the standards for a particular department? I am now facing the same issue with 304 when used in solutions containing chloride ions, and I would like to know if there are any standards available that specify the critical concentration for its use
The critical chlorine content that can lead to crevice corrosion in a simulated desulfurization tower environment at a temperature of 80°C: Alloy ASTM EN* Cl-ppm 316L 316L 1.4404 50 904L N08904 1.4539 500 254SMO S31254 1.4547 5000 654SMO S32654 1.4652 12500 Alloy 625 NO6625 2.4856 4000–5000**
The corresponding chloride ion concentration should be reduced further, as there are many complex factors in practical applications; elements such as welds and pits can accelerate corrosion. The welds are mainly smooth with gentle transitions; passivation should provide effective corrosion protection, as this is a weak point. The impellers of 316 mixers often break at the welds.