What's the difference between 20# steel and Q345 steel?

There is no difference in appearance between 20# steel and Q345 steel. These two kinds of steel are widely used steel grades, of which 20# seamless steel pipe is easier to find stock than Q345 seamless steel pipe on the market.

20# steel is high-quality carbon structural steel, also known as carbon structure steel, commonly known as high-quality steel. In 20# steel, no alloy element is specially added. 20# steel is mainly used in machine structure manufacturing, and has become non alloy steel for machine manufacturing. 20# steel is a kind of high-quality structural steel with a large amount of use. 20# steel has higher strength than Q195 steel, good weldability and no temper brittleness. Machinability of 20# steel can be improved by water quenching.

Q345 steel is a kind of low-alloy high-strength steel. Q345 steel contains a small amount of alloy elements. Q345 steel is mainly used for building and engineering structures. The carbon content of Q345 steel is 0.20%. Due to the effect of alloy elements, the yield strength of low-alloy high-strength structural steel is 25% - 150% higher than that of carbon structural steel with the same carbon content. The use of low-alloy high-strength structural steel instead of carbon structural steel can reduce the weight of the structure, save metal materials and prolong service life of the structure.