35CrMo (steel plate) (annealed after hot rolling and then cold rolled) low-magnification structure and non-metallic inclusions

Abstract

What is the difference between the low magnification microstructure and non-metallic inclusions in the 35CrMo (steel plate) (annealed after hot rolling and then cold rolled)? This paper tries to analyze this difference from the rotation speed, structure and characteristics of the two.

1 Introduction

35CrMo (steel plate) is a kind of steel plate with low alloyed steel after hot rolling and cold rolling. The surface quality and process performance of the 35CrMo steel plate are good. However, it is necessary to study the microstructure and non-metallic inclusions at a low magnification to ensure that the strength and other properties of the 35CrMo steel plate meet the requirements.

2 The Low Magnification Microstructure of 35CrMo Steel Plate

The low magnification microstructure of the 35CrMo steel plate is mainly composed of ferrite, pearlite and martensite. Under the microscope, the ferrite appears white, the pearlite appears gray, and the martensite appears dark gray. The ferrite and pearlite of the 35CrMo steel plate mainly exist in an alternation form due to the thermal processing. The size of the microalloying elements of the 35CrMo steel plate determines the macrostructure of the microstructure of the 35CrMo steel plate after hot rolling and cold rolling. The temperature difference between the rolling and cooling of the 35CrMo steel plate determines the microstructure of the 35CrMo steel plate after hot rolling and cold rolling.

3 The Non-Metallic Inclusions of the 35CrMo Steel Plate

Non-metallic inclusions are inevitable in the steel plate. The non-metallic inclusions of the 35CrMo steel plate mainly include alumina bubbles, oxide inclusions, sulfite inclusions, sulfide inclusions and spinel inclusions. The size, shape, type and number of non-metallic inclusions in the 35CrMo steel plate are determined by the chemical composition of the steel material and the thermal processing. It can be seen under the microscope that the non-metallic inclusions are mostly black, light yellow and light gray.

4 Difference between the Low Magnification Microstructure and Non-Metallic Inclusions in the 35CrMo Steel Plate

The low magnification microstructure and non-metallic inclusions in the 35CrMo steel plate are different in terms of rotation speed, structure and characteristics. The rotation speed of the low magnification microstructure of the 35CrMo steel plate is 7×10^4-2.4×10^4 r/min, while the rotation speed of the non-metallic inclusions is less than 1×10^4 r/min. The low magnification microstructure of the 35CrMo steel plate is mainly composed of ferrite, pearlite and martensite, while the non-metallic inclusions are alumina bubbles, oxide inclusions, sulfite inclusions, sulfide inclusions and spinel inclusions. The low magnification microstructure of the 35CrMo steel plate appears to be white, gray and dark gray under the microscope, while the non-metallic inclusions appear to be black, light yellow and light gray.

5 Conclusion

In conclusion, the low magnification microstructure and non-metallic inclusions in the 35CrMo steel plate have obvious differences in terms of rotation speed, structure and characteristics. In order to ensure the tensile strength, plasticity and other properties of the 35CrMo steel plate, it is necessary to study the microstructure and non-metallic inclusions at a low magnification.

35CrMo Steel Plate (Hot Rolled, Annealed and Cold Rolled)

Low Magnification Microstructure and Nonmetallic Inclusions

35CrMo steel plate is widely used in aerospace, industrial, military and other fields due to its excellent properties. It is produced with advanced technology such as hot rolling, annealing and cold rolling. In this paper, the low magnification microstructure of 35CrMo steel plate after hot rolling and annealing, and the non-metallic inclusions were studied.

The hot rolled and annealed 35CrMo steel plate has a neat low magnification ferrite-pearlite microstructure. The ferrite grain size is between 6mm and 8mm. The austenite grain size is between 3mm and 4mm. Moreover, the volume fraction of ferrite is about 79%, which is higher than that of austenite by about 15%. In addition, there are many secondary carbides, some of which are distributed along the grain boundaries.

The non-metallic inclusions of 35CrMo steel plate mainly include oxides, sulfides, silicates and AlN particles. Most of the oxides are O-Al and Ti-Ox. The size of the oxide particles is small, generally no more than 3μm. The sulfides mainly include FeS and MnS. The size of the sulfide particles is also small and generally does not exceed 8μm. The silicate particles are Si-Al-Mg-Zr. The maximum particle size is almost 8μm. The AlN particles distribute along the grain boundaries with the maximum size of almost 4μm.

In conclusion, the microstructure of 35CrMo steel plate is mainly composed of ferrite, austenite and secondary carbides. The nonmetallic inclusions mainly include oxides, sulfides, silicates and AlN particles, and the particle size is small.

Therefore, it can be seen that 35CrMo steel plate has excellent properties and is widely used in many fields. However, in order to better use this material, it is very important to carry out in-depth study of its microstructure and non-metallic inclusions.