Q345E is the grade of steel, which belongs to low-alloy high-strength steel plate and has good low-temperature impact performance. The steel grade consists of three parts: Chinese pinyin letters representing the yield strength, yield strength value and quality grade symbol.
16Mn is the old country brand name, and now it is classified into low-alloy high-strength structural steel. The current grade is called Q345, but Q345 steel is the substitute of many old steel grades such as 12MnV, 14MnNb, 18Nb, 16MnRE and 16Mn. It is not just a substitute for 16Mn steel.