Low alloy steel is relative to carbon steel. Based on carbon steel, it is intended to add one or more alloying elements to steel to improve its performance. When the amount of alloy added exceeds the general content of carbon steel in the normal production method, the steel is called alloy steel. When the total amount of alloy is less than 5 %, it is called low alloy steel. Ordinary alloy steel is generally below 3.5 %. Alloy content between 5-10 % is called medium alloy steel, and more than 10 % is called high alloy steel.
The steel grade comprises three parts: the Chinese phonetic alphabet representing the yield strength, the yield strength value, and the quality grade symbol, such as Q345D. Among them:
Q – steel yield strength of the 'Qu' character Chinese Pinyin first letter;
345 – yield strength value, unit MPa;
D – quality grade is D (grade is divided into A, B, C, D, E).
When the demand side needs the steel plate to have the thickness direction performance, the symbol representing the thickness direction (Z direction) performance level is added after the above specified brand, such as Q345DZ15.
