Carbon Structural Steel

Heat treatment and microstructure specifications :
Heat treatment specifications: normalizing , 910 ℃.
Difference:
20Mn 20Mn2 with distinction : the chemical composition of these two steels ( same carbon content, manganese content ) , mechanical properties , heat treatment has a different main differences are as follows : 20Mn- quality carbon structural steel is a chemical composition ( % ): C: 0.17 ~ 0.23Si: 0.17 ~ 0.37Mn: 0.7 ~ 1.00Cr ≤ 0.25Ni ≤ 0.30Cu ≤ 0.25 mechanical Properties : tensile strength ≥ 450MPa yield strength ≥ 275MPa elongation ≥ 24% Reduction of ≥ 50% Heat treatment: normalizing , carbon, nitrogen permeation 20Mn2- alloy steel chemical composition (%): C: 0.17 ~ 0.24Si: 0.17 ~ 0.37Mn: 1.40 ~ 1.80 mechanical properties: tensile strength ≥ 785MPa yield strength ≥ 590MPa elongation rate of ≥ 10% ≥ 40% Reduction of impact energy ≥ 47Aku2 J heat treatment : quenching ( water, oil quenching ) , tempering ( water , air ) , carburizing .