Which is better, grade 12.9 screw and stainless steel screw?
According to the composition can be divided into Cr system (SUS400), (SUS300), Cr Mn Ni Cr Ni system (SUS200) and the precipitation hardening systems (SUS600).Therefore, the stainless steel screws do not have so high strength. If you do not use the environment and conditions do not need so high intensity, you can still use 8.8 stainless steel screws.
Stainless steel is usually divided into matrix tissue:1 ferritic stainless steel. Chromium 12% ~ 30%. Its corrosion resistance, toughness and weldability increase with the increase of chromium content, and the resistance to chloride stress corrosion is better than other kinds of stainless steel.2 austenitic stainless steel. Chromium more than 18%, but also contains about 8% of nickel and a small amount of molybdenum, titanium, nitrogen and other elements. Good comprehensive performance, corrosion resistant variety of media.3 austenite ferrite duplex stainless steel. It has the advantage of austenite and ferritic stainless steel and has superplasticity.4 martensitic stainless steel. High strength, but poor plasticity and weldability.5 、 precipitation hardening stainless steel. With excellent formability and good weldability, it can be used as an ultra high strength material in the nuclear industry, aviation and aerospace industry.
Look at the environment used, in the corrosive environment, stainless steel screws, anti-oxidation, corrosion resistance, stainless steel screws a little betterIn the high strength and high impact environment, grade 12.9 is the top grade of screw. It has high hardness and tensile strength. Its Rockwell hardness (HRC) can reach 39-44, and tensile strength can reach 1220N/mm2
