The difference between 16Mn seamless steel tube and Q345 seamless steel tube

Q345 steel is the replacement of the old no. 12MnV, 14MnNb, 18Nb, 16MnRE, 16Mn and other steel types, instead of only replacing the material of 16Mn steel.

In terms of chemical composition, 16Mn and Q345 are also different.More importantly, there is a great difference in the thickness of the two kinds of steel according to the yield strength, which will inevitably cause the change of allowable stress of some thickness of the material.

Therefore, it is inappropriate to simply apply the allowable stress of 16Mn steel to Q345 steel, but the allowable stress should be redetermined according to the new steel thickness grouping size.

The proportion of main components of Q345 steel is basically the same as that of 16Mn steel, except that V, Ti and Nb trace alloying elements are increased.A small amount of V, Ti, Nb alloy can refine grain, improve toughness of steel, and improve the comprehensive mechanical properties of steel.

Because of this, the thickness of the steel plate can be made larger.Therefore, the comprehensive mechanical properties of Q345 steel should be better than that of 16Mn steel, especially its low temperature performance is more than that of 16Mn steel.The allowable stress of Q345 is slightly higher than that of 16Mn steel.