Q1: What are the key chemical composition requirements for 12Cr1MoVG steel pipe?
The carbon content of 12Cr1MoVG steel pipe is controlled between 0.08% and 0.15% to ensure good weldability and high-temperature strength. The chromium (Cr) content is 1.00% to 1.50%, providing oxidation and corrosion resistance. The molybdenum (Mo) content is 0.25% to 0.35%, enhancing high-temperature creep resistance. The vanadium (V) content is 0.15% to 0.30%, refining the grain size and improving toughness. Phosphorus (P) and sulfur (S) contents are limited to below 0.025% and 0.010%, respectively, to reduce brittleness. These compositional characteristics make it suitable for high-temperature and high-pressure environments, such as power plant boilers and petrochemical equipment.
Q2: What are the mechanical properties of 12Cr1MoVG steel pipe? 12Cr1MoVG steel pipe has a room-temperature yield strength of ≥275 MPa, a tensile strength of 440-640 MPa, and an elongation of ≥19%. At high temperatures (e.g., 550°C), its endurance strength reaches ≥90 MPa (100,000-hour fracture strength). Impact toughness requires a room-temperature impact energy of ≥31 J to ensure safety under low-temperature conditions. Hardness is controlled to HB ≤ 170, balancing strength and processability. These properties make it an ideal material for high-temperature, pressure-bearing equipment.
Q3: What are the main differences between 12Cr1MoVG and 15CrMoG steel pipes?
12Cr1MoVG has a lower chromium content (1.00%-1.50%) than 15CrMoG (1.20%-1.60%), but a higher vanadium content. 12Cr1MoVG offers superior high-temperature strength to 15CrMoG, especially at temperatures above 550°C. 15CrMoG has slightly better weldability, but 12Cr1MoVG has stronger creep resistance. 12Cr1MoVG is 5%-10% more expensive than 15CrMoG due to its higher alloy cost. In terms of application, 12Cr1MoVG is primarily used in supercritical boilers, while 15CrMoG is commonly used in subcritical equipment.
Q4: What temperature range is 12Cr1MoVG steel pipe suitable for?
The designed operating temperature range of 12Cr1MoVG is -20°C to +580°C, and it can withstand temperatures up to 600°C for short periods. Its creep strength and oxidation resistance are excellent in the 450°C to 580°C range. In low-temperature environments (such as -20°C), an impact energy of 31J or higher is required to prevent brittle fracture. Above 600°C, higher-grade P91/P92 steel is recommended. Thermal fatigue issues require special attention in operating conditions with frequent temperature fluctuations.
Q5: What are the delivery conditions for 12Cr1MoVG steel pipe? 12Cr1MoVG steel pipes are typically delivered in the normalized (N) and tempered (T) condition, with normalizing temperatures ranging from 930°C to 960°C and tempering temperatures ranging from 680°C to 730°C. Thick-walled pipes (>30mm) may require quenching and tempering (quenching and tempering). Cold-drawn pipes require stress relief annealing (600°C to 650°C). Heat treatment curves and mechanical property reports are required upon shipment. Special applications may require additional high-temperature endurance test data.
