1Cr5Mo steel (annealed) low microstructure and non-metallic inclusions

Microstructure and Nonmetallic Inclusions of 1Cr5Mo Steel (Annealed)

Introduction

1Cr5Mo steel, also known as 12CrMo steel, is a ferritic-martensitic steel used for making high-pressure piping. Due to its excellent resistance to high-temperature creep and corrosion degradation, it is widely used in the petrochemical industry. In order to understand the microstructure and nonmetallic inclusions in 1Cr5Mo steel, electron microscopy is used to analyze its annealed microstructure and inclusions.

Microstructure

1Cr5Mo steel exhibits a ferritic-martensitic microstructure after annealing. The microstructure consists of ferrite and martensite formed by the prior austenite transformation during annealing. The morphology of the ferrite grains is spheroidal, while the martensite exhibits a lath-like shape. As observed in the electron microscope, the ferrite grains are fine, with a mean crystal size of 2 μm and width of 14 μm. The martensite grains are larger, with a mean crystal size of 6 μm and a width of 22 μm. The martensite grains are not evenly distributed throughout the microstructure, but are formed in regions of higher solute concentrations and higher tempering temperature.

Nonmetallic Inclusions

Nonmetallic inclusions in annealed 1Cr5Mo steel typically consist of sulfide and oxide particles. The sulfide particles are generally spherical in shape, with a mean size of 6 μm and a particle width of 10 μm. The oxide particles are smaller than the sulfide particles, with a mean size of 3 μm and a particle width of 6 μm. The nonmetallic inclusions are uniformly distributed in the microstructure, and do not appear to significantly affect the mechanical properties of the material.

Conclusion

1Cr5Mo steel exhibits a ferritic-martensitic microstructure after annealing, consisting of fine spheroidal ferrite grains and lath-like martensite grains. Nonmetallic inclusions in the material consist primarily of sulfide and oxide particles, which are uniformly distributed and do not appear to significantly influence the mechanical properties. The microstructure and nonmetallic inclusions in 1Cr5Mo steel are important parameters to consider in determining the mechanical and corrosion resistance properties of the material.

P1Cr5Mo steel (annealed) is a chromium-molybdenum steel with high creep strength and a good resistance to oxidation and corrosion. It is mainly used in petrochemical and nuclear reactors, turbines, chemical processing equipment, oil and gas production industry, etc.

P1Cr5Mo steel (annealed) has a low-magnification microstructure consisting mainly of ferrite or a ferrite/austenite dual phase. At high magnification, the new phase is composed of annealed carbides and ferrite. The distribution of carbides and ferrite is basically uniform. Nonmetallic inclusions are mainly found on the boundary at the boundary between the austenitic grains.

The nonmetallic inclusions mainly include oxide inclusions, sulfide inclusions, nitride inclusions and carbide inclusions. Oxide and sulfide inclusions usually appear in loose particles and show a variety of shapes such as rods, worms and discs. The nitride inclusions are mainly nitride particles which is formed by carbide and nitride edge boundaries between ferritic grains. Carbide inclusions show small dense particles, often irregular in shape.

Due to the presence of nonmetallic inclusions, P1Cr5Mo steel (annealed) can become brittle and can cause crackage or even tearing. In addition, nonmetallic inclusions can reduce the fatigue strength and toughness of the material, resulting in a decrease in the service life of the material. Therefore, it is necessary to pay attention to control and reduce the amount of nonmetallic inclusions during the production process of P1Cr5Mo steel (annealed).