ASTM A515 gr70 steel composition: manganese and silicon effects

ASTM A515 gr70 is a type of carbon-silicon steel plate used in pressure vessel applications. Its composition is primarily made up of carbon, manganese, and silicon.

Manganese is added to improve the strength and toughness of the steel. It also helps to refine and homogenize the microstructure by promoting the formation of fine-grained pearlite during cooling. The typical manganese content in ASTM A515 gr70 is between 0.90% and 1.50%.

Silicon is added to promote deoxidation, which improves the steel's ability to resist cracking during welding and other hot-working processes. This element also aids in the formation of ferrite, which enhances the steel's high-temperature strength and resistance to corrosion. The typical silicon content in ASTM A515 gr70 is between 0.15% and 0.40%.

Overall, the combination of carbon, manganese, and silicon in ASTM A515 gr70 results in a high-strength, low-alloy steel with excellent weldability and formability, making it suitable for use in a wide range of pressure vessel applications.