What is the difference between 12Cr1MoV and 12Cr1MoVG steel

What is the difference between 12Cr1MoV and 12Cr1MoVG steel?

12Cr1MoV and 12Cr1MoVG steel are GB standard steel grades. 12Cr1MoV steel belongs to alloy structural steel, while 12Cr1MoVG steel belongs to high-pressure boiler steel, in which G means boiler and high-pressure. The use environment of the two materials is completely different.  12Cr1MoV steel is ordinary structural steel, 12Cr1MoVG steel is high-pressure and high-temperature resistant steel, and their chemical composition is slightly different.

The chemical composition of 12Cr1MoVG steel: C 0.08 - 0.15, Si 0.17 - 0.37, Mn 0.40 - 0.70, Mo 0.25 - 0.35, Cr 0.90 - 1.20, V 0.15 - 0.30.

The mechanical properties of 12Cr1MoVG steel: tensile strength σb (MPA): ≥ 490, yield strength σs (MPA): ≥ 245, elongationδ5 / (%): ≥ 22.