12Cr1MoV

12Cr1MoV

Alloy structural steel, digital code: A31132. Standard: GB/T3077-1999

2 Chemical Composition

　　C：0.08～0.15Si：0.17～0.37

　　Mn：0.40～0.70

　　Cr：0.90～1.20

　　Mo：0.25～0.35

　　V：0.15～0.30

3 Mechanical Properties

Sample blank dimensions

　　30mm

Heat Treatment

Quenching heating temperature (℃): 970; Cooling agent: air

Hardening Heat Temperature (℃): 750; Coolant: Air

【Mechanical Properties】

Tensile Strength (σb/MPa): ≥490

Yield Point (σs/MPa): ≥245

Final elongation rate (δ5/%): ≤22

Section reduction rate (ψ/%): ≥50

Impact Absorption Work (Aku2/J): ≥71

Impact toughness value αkv (J/cm2): ≥88(9)

Brinell Hardness (HBS 100/3000) (Annealed or High-Temperature Quenched Condition): ≤179

At room temperature: Allowable tensile stress (σw/MPa): 93, Allowable bending stress (σw/MPa): 112, Allowable shear stress (T/MPa): 56

4 Key Features

Key Features: Compared to 12CrMoV steel, this steel boasts higher oxidation resistance and thermal strength. Its creep strength and endurance values are nearly identical, and it exhibits high plasticity under endurance stretching conditions. The steel has good processability and weldability, but it requires preheating to 300°C before welding and stress relief treatment after welding.

This steel grade is widely used in high-pressure, ultra-high-pressure, and subcritical power plant boilers for superheaters, headers, and main steam ducts. It retains high thermal strength and oxidation resistance at 580°C, with good ductility. The production process is relatively simple, and it has good weldability, although it is sensitive to normalizing cooling rates. Long-term use at 580°C can lead to spheroidization of the pearlite.

5 Application Examples

This steel is primarily used after normalizing and high-temperature tempering, for manufacturing overheat pipes, conduits, serpentine pipes, and other corresponding forgings for high-pressure equipment where the operating temperature does not exceed 570 to 585°C.

6 Relevant Calculations

Alloy tube weight calculation formula:

[(OD - WT) * WT] * 0.02466 = kg/m (weight per meter) (unit: mm)

Alloy steel plate weight calculation formula:

Length x Width x Height x 0.00785 = kg

7 Detailed Introduction

① The two-digit number at the beginning of the steel grade indicates the carbon content of the steel, expressed as a percentage of the average carbon content per ten thousand, such as 40Cr, 25Cr2MoVA alloy pipe.

② The main alloy elements in steel, except for some microalloying elements, are generally indicated as a percentage. When the average alloy content is less than 1.5%, the steel grade typically only shows the element symbol without specifying the content. However, in special cases where confusion may arise, a number "1" can also be added after the element symbol, e.g., in the steel grades "12CrMoV" and "12Cr1MoV," the former contains 0.4-0.6% chromium, and the latter contains 0.9-1.2%, with all other components being identical. When the average content of alloy elements is ≥1.5%, ≥2.5%, ≥3.5%, and so on, the content should be indicated after the element symbol, which can be represented as 2, 3, 4, etc. For example, in 18Cr2Ni4WA.

③ Vanadium (V), titanium (Ti), aluminum (Al), boron (B), and rare earth elements (RE) in steel are all microalloying elements. Although their content is low, they should still be indicated in the steel grade. For example, in 20MnVB steel, vanadium is 0.07-0.12%, and boron is 0.001-0.005%.

④ Steel should be marked with "A" after the steel number to differentiate it from ordinary steel.

⑤ Alloy structural steel for special purposes, with the steel grade prefixed (or suffixed) by symbols representing the purpose of the steel. For example, the 30CrMnSi steel for rivet bolts is designated as ML30CrMnSi.

Alloy tubes and seamless tubes are related yet distinct; they should not be confused.

Alloy tubes are defined by the materials used in their production (i.e., the material), as the name suggests, they are tubes made of alloy; while seamless tubes are categorized by their production process (seamed or seamless). Unlike seamless tubes, seamed tubes include straight seam welded tubes and spiral tubes.

12Cr1MoV corresponds to the international grade 16Mo3. During welding, preheating is required, and the weld should be kept warm for about 30 minutes after welding is completed. Manganese in 16Mo3 steel is an important alloying element and a key hardenability element, significantly affecting the toughness of the weld metal. When the Mn content in 16Mo3 steel is less than 0.05%, the weld metal has high toughness; it becomes very brittle when the content exceeds 3%; when the Mn content is between 0.6% to 1.8%, the weld metal exhibits high strength and toughness.