15CrMo boiler tubes

15CrMo boiler tube is based on high-quality carbon structural steel, and one or several alloying elements are appropriately added to improve the mechanical properties, toughness and hardenability of steel. Products made of this type of steel usually require heat treatment (normalizing or quenching and tempering); the parts and components made of such steel usually need to undergo quenching and tempering or surface chemical treatment (carburizing, nitriding, etc.), surface Quenching or high-frequency quenching and other treatments. Therefore, according to the chemical composition (mainly carbon content), heat treatment process and use, this type of steel can be roughly divided into three types: carburizing, quenching and tempering and nitriding.

Low-alloy heat-resistant steel is stronger than 12CrMo steel, with slightly lower toughness. It has higher heat resistance and oxidation resistance at 500 - 550 °C or lower, along with good mechanical properties, machinability, and cold strain plasticity. The weldability is fair. It is mainly used for the production of seamless steel pipes and sheets of various calibers.

12Cr5MoI seamless steel tube is a type of steel tubing that is made from the 12Cr5MoI alloy, which is a low-alloy high-strength structural steel. This type of steel is known for its excellent mechanical properties, including high strength, good toughness, and wear resistance.

The 15CrMo boiler tube is a type of seamless steel tube used primarily in the construction of boilers, superheaters, and pressure vessels due to its high-temperature strength and resistance to oxidation and corrosion.

Features

• High-Temperature Strength
• Oxidation and Corrosion Resistance
• Durability

Standards

• Chinese Standard: GB/T 5310
• International Standards: ASTM A335 P11, DIN 17175 13CrMo44

Heat treatment process

15CrMo Boiler Tube Representation Method

1. Carbon Content

The two digits at the beginning of the steel number indicate the carbon content of the steel, expressed in ten-thousandths of the average carbon content. Example: 40Cr indicates approximately 0.40% carbon content.

2. Main Alloying Elements

Main alloying elements are expressed in percent. If the content is less than 1.5%, only the element symbol is indicated. Example: 12CrMoV (0.4-0.6% Cr) vs. 12Cr1MoV (0.9-1.2% Cr). For contents ≥1.5%, the element symbol is followed by numbers: Example: 18Cr2Ni4WA.

3. Microalloying Elements

Elements such as V, Ti, Al, B, and RE are marked even when their content is very low. Example: 20MnVB (0.07-0.12% V, 0.001-0.005% B).

4. Quality Indicators

High-quality steel is marked with an "A" at the end of the steel number to distinguish it from general quality steel.

5. Special Purpose Alloy Structural Steel

Steel for special purposes may have a prefix or suffix indicating its application. Example: ML30CrMnSi for riveting screws.

Alloy tubes and seamless tubes have both similarities and differences and should not be confused. The alloy pipe is defined by the steel pipe according to the production materials (i.e. the material), as the name suggests, it is a pipe made of alloy; while the seamless pipe is defined by the steel pipe according to the production process (seamless), which is different from the seamless pipe. Seam welded tubes, including straight seam welded tubes and spiral tubes.

Manufacturing Process of 15CrMoG Alloy Pipe

The manufacturing process of 15CrMoG alloy pipe involves precision engineering and advanced techniques to ensure its quality and reliability. The production starts with the selection of high-quality raw materials, followed by melting and refining processes to achieve the desired chemical composition. Subsequently, the pipe undergoes hot rolling, cold drawing, and heat treatment to attain the desired mechanical properties.

Applications of 15CrMoG Alloy Pipe

The 15CrMoG alloy steel, due to its excellent comprehensive properties, is widely used in various industries, including:

1. Petroleum Industry: Used in the manufacturing of high-temperature and high-pressure equipment such as heating furnace tubes and hydrocracking tubes.
2. Chemical Industry: Applicable in the production of high-pressure equipment and pipelines for processes like high-sulfur petroleum, residuum hydrogenation, and synthetic ammonia.
3. Power Industry: Employed in the fabrication of high-temperature and high-pressure steam pipes, turbine blades, boilers, and other equipment.

The production standards for 15CrMoG alloy steel include GB/T 3077-2015 "Alloy Structure Steel" and ASME SA335/SA335, which strictly specify requirements for chemical composition, mechanical properties, metallographic structure, surface quality, etc., ensuring the quality and reliability of the material. Additionally, various testing methods, including non-destructive testing and physical and chemical testing, are employed to ensure that the product meets the required quality standards.

Classification of High Pressure Boiler Tubes

1. High-quality carbon structural steel grades are 20G, 20MnG, and 25MnG.
2. Alloy structural steel grades 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB, etc.
3. The commonly used 1Cr18Ni9 and 1Cr18Ni11Nb boiler tubes with rust and heat-resistant steels should be subjected to hydrostatic tests, flaring and flattening tests one by one in addition to ensuring chemical composition and mechanical properties. Steel pipes are delivered in heat-treated condition.

In addition, there are certain requirements for the microstructure, grain size and decarburization layer of the finished steel pipe.

Specifications and Appearance Quality of High-Pressure Boiler Tubes

GB5310-95 "Seamless Steel Tubes for High-Pressure Boilers" has an outer diameter of 22-530mm and a wall thickness ranging from 20-70mm. The outer diameter of the cold drawn (cold rolled) tube is 10-108mm, and the wall thickness is 2.0-13.0mm.

The Principle of Purifying Hydrogen by 15CrMo Boiler Tube

The principle of purifying hydrogen by 15CrMo boiler tube is that when the hydrogen to be purified is passed into one side of the 15CrMo boiler tube at 300-500 ℃, the hydrogen is adsorbed on the wall of the 15CrMo boiler tube, because the 4d electron layer of palladium lacks two Electrons, which can form unstable chemical bonds with hydrogen (this reaction between palladium and hydrogen is reversible), under the action of palladium, hydrogen is ionized into protons with a radius of 1.5 × 1015m, while the lattice constant of palladium is 3.88 ×10-10m (at 20°C), so protons can be combined with electrons through the 15CrMo boiler tube under the action of palladium to form hydrogen molecules again, and escape from the other side of the 15CrMo boiler tube. On the surface of the 15CrMo boiler tube, the undissociated gas is impermeable, so the 15CrMo boiler tube can be used to obtain high-purity hydrogen.

15CrMo Boiler Tube Representation Method

1. The two digits at the beginning of the steel number indicate the carbon content of the steel, expressed in ten thousandths of the average carbon content, such as 40Cr.
2. The main alloying elements in steel, except for individual microalloying elements, are generally expressed in percent. When the average alloy content is less than 1.5%, only the element symbol is generally indicated in the steel number, but the content is not indicated. However, in special cases, if it is easy to cause confusion, the number "1" can also be marked after the element symbol, such as the steel number. "12CrMoV" and "12Cr1MoV", the former has a chromium content of 0.4-0.6%, the latter is 0.9-1.2%, and the rest of the components are all the same. When the average content of alloying elements is ≥1.5%, ≥2.5%, ≥3.5%..., the content should be indicated after the element symbol, which can be expressed as 2, 3, 4...etc. For example 18Cr2Ni4WA.
3. Alloying elements such as vanadium V, titanium Ti, aluminum AL, boron B, and rare earth RE in steel are all microalloying elements. Although the content is very low, they should still be marked in the steel grade. For example, in 20MnVB steel. Vanadium is 0.07-0.12% and boron is 0.001-0.005%.
4. High-quality high-quality steel should add "A" at the end of the steel number to distinguish it from general high-quality steel.
5. For special purpose alloy structural steel, the steel number is crowned (or suffixed) with a symbol representing the purpose of the steel. For example, the special 30CrMnSi steel for riveting screws, the steel number is expressed as ML30CrMnSi.

Alloy pipes and seamless pipes have both relationships and differences, and should not be confused.

Alloy pipe is defined by the steel pipe according to the production materials (that is, the material), as the name suggests, it is a pipe made of alloy; while the seamless pipe is defined by the steel pipe according to the production process (seamless), which is different from the seamless pipe. Seamed pipes, including straight seam welded pipes and spiral pipes.

15CrMoHot Rolled Plates

The microstructure of 15CrMo alloy steel in normal supply state is ferrite plus pearlite.

In the long-term operation of 15CrMo steel in the working temperature range of 500°C - 550°C, pearlite spheroidization will occur, and alloying elements will be between solid solution and carbide. The redistribution and the change of the structure of the carbide phase, the thermal strength and mechanical properties of the 15CrMo steel gradually decrease with the degree of spheroidization of the pearlite and the degree of depletion of the solid solution, so that the material gradually deteriorates or even fails. Therefore, the degree of pearlite spheroidization in 15CrMo steel structure has long been widely used as one of the important criteria for determining the reliability of the use of this type of steel.

15CrMoHot Rolled Plates Specification