Different: The lower limit of the yield strength of Q235 is 235 MPa, and the lower limit of the yield strength of Q345 is 345 MPa (the meaning of Q is the "yield" in Chinese characters, the latter value represents the lower limit of yield strength) 2. The alloy content of the two is different: Q235 is ordinary carbon steel , Q345 is low alloy steel
Q235 is a carbon structural steel, compared with the old standard GB700-79 grades A3 and C3
Q345 is a low-alloy structural steel, compared with the old standard 1591-88 12MnV, 16Mn 16MnRE, 18Nb, 14MnNb
As far as performance and applications go,
Q235--Metal structural parts, carburized or cyanide parts with low core strength requirements, tie rods, connecting rods, hooks, couplers, bolts and nuts, sleeves, shafts and welded parts
Q345--Comprehensive mechanical properties, good low temperature performance, good plasticity and weldability, used as medium and low pressure vessels, oil tanks, vehicles, cranes, mining machinery, power stations, bridges and other structures that bear dynamic loads, mechanical parts, building structures 、 General metal structures, hot rolled or normalized, can be used for various structures in the cold area above -40 ℃
