Generally speaking, stainless steel flange products cast with non-magnetic 304 stainless steel have a certain degree of ferromagnetism. What is the reason for this? There are probably several reasons:
Firstly, the equivalent chemical composition has not been properly controlled
Stainless steel flange manufacturers control the lower limit of Ni at 8.0-8.2% in order to reduce costs. When Cr/Ni reaches a certain value, a certain amount of ferrite appears in the steel structure, which is magnetic; At this time, ferrite can be completely dissolved into austenite after 1050-1080 solid solution treatment, so it has no magnetism.
Secondly, during cold work hardening of austenitic stainless steel, deformation martensite is generated, which increases the strength of the stainless steel, and deformation martensite has magnetic properties. Solution treatment or even annealing can cause the disappearance of deformed martensite, but the strength of the steel will decrease.
Stainless steel flanges have good metal properties and strong corrosion resistance, and are commonly used in steel structures, such as stainless steel flanges. Stainless steel flanges have also become stainless steel and acid resistant steel flanges, with smooth metal surfaces that are not easily oxidized by air, so they are commonly used in high-pressure water pipes and corroded pressure pipelines.
Firstly, as a metallic material, it reacts with air in humid environments, thereby altering its original metallic properties. Stainless steel flanges can be purified with oxidants, forming a tough and dense smoke emitting oxide protective film Cr203 on the surface. Stainless steel flanges can effectively prevent oxidation reactions from occurring. The passivation ability of other metal pipes such as galvanized water pipes and copper pipes is very small, which is the key reason why the corrosion resistance of galvanized copper pipes is far inferior to that of stainless steel pipes. So the corrosion resistance of stainless steel flanges indicates that they will not corrode uniformly like carbon steel, and do not require protective coatings during use; Stainless steel flange adopts stainless steel flange water pipe, which has no restriction on the chemical composition of water, because stainless steel is suitable for various oxygen content, temperature PH, Hard water has good corrosion resistance; Stainless steel water pipes can withstand high flow rates, even if the flow rate is greater than 40 m/s, the corrosion rate is still extremely low, not exceeding 0.003mm/year, especially suitable for high-rise water supply. The thermal expansion coefficient of stainless steel flange pipes is approximately equal to that of copper pipes, which is 1.5 times that of ordinary steel pipes. Compared with stainless steel flange pipes, stainless steel flange pipes have the characteristics of thermal expansion and contraction.
In addition, the chemical reaction of stainless steel flanges is generally integral, and a protective film will form on the surface, which cannot be achieved by any metal.
