2CrMnMo (diameter 16mm round steel) (carbonitriding after hot rolling) low-magnification structure and non-metallic inclusions

Introduction

This report focuses on the microstructure, composition, and non-metallic inclusions of 16mm diameter hot-rolled carbon-nitrogen-alloyed steel with 2CrMnMo composition. In general, steels should have a balance between mechanical strength, toughness and weldability, but such properties must be evaluated for each application. The introduction of carbon and nitrogen into the steel composition affects the properties of the steel. The microstructure, composition, and non-metallic inclusions of this steel can be used to predict its mechanical properties.

Objective

The goal of this report is to examine the microstructure, composition, and non-metallic inclusions of 16mm diameter hot-rolled carbon-nitrogen-alloyed steel with 2CrMnMo composition.

Materials and Methods

The 16mm diameter hot-rolled steel used in this study was obtained from a steel products business. The chemical composition of the sample was analyzed by optical emission spectrometry (OES) and was found to be 2.0% C, 0.8% Mn, 1.4% Cr, and 0.3% Mo. The microstructure of the sample was studied using X-ray diffraction methods. Non-metallic inclusions were investigated using an optical microscope and scanning electron microscope.

Results and Discussion

The results of the OES analysis showed that the sample had a chemical composition of 2.0% C, 0.8% Mn, 1.4% Cr, and 0.3% Mo. The microstructure of the hot-rolled steel was studied by X-ray diffraction and revealed the presence of acicular ferrite, carbide and nitride clusters, globular pearlite, and small amounts of ferrite-cementite particles.

Under the microscope, non-metallic inclusions in the 16mm diameter sample were observed to be predominantly oxides and sulfides. These inclusions consisted mainly of titanium oxide (TiO2), calcium oxide (CaO), manganese oxide (MnO2), and silicate (SiO2). These inclusions are usually present in high carbon steels and are a major contributor to the mechanical properties of steel.

Conclusion

The chemical composition of the 16mm diameter hot-rolled steel sample with 2CrMnMo composition was found to be 2.0% C, 0.8% Mn, 1.4% Cr, and 0.3% Mo. The microstructure of the steel consisted of acicular ferrite, carbide and nitride clusters, and globular pearlite. Non-metallic inclusions were predominantly oxides and sulfides of titanium oxide, calcium oxide, and manganese oxide. These inclusions are essential to the mechanical properties of the steel and must be taken into account to ensure the desired performance of the steel.

St20Cr2CrMnMo is a kind of hot-rolled low carbon steel round bar with a diameter of 16mm. It is a kind of low alloy carburizing steel, composed of St20Cr2CrMnMo, which belongs to the heat treated low alloy carburizing steel. This steel material has good comprehensive mechanical properties, excellent heat treated and corrosion resistance, especially nitridation and carburization, it also has good machinability and weldability.

The main components of St20Cr2CrMnMo are: Cr: 2.0-2.4%, Mo: 0.35-0.40%, Mn: 1.30-1.70%, C: 0.17-0.23%, Si: 0.17-0.37%, S: 0.030% max., P: 0.035% max., and Ni: 0.30% max. The microstructure of St20Cr2CrMnMo is mainly composed of tempered spheroidized carbides, granulated bainite, and a small amount of residual austenite. At the same time, non-metallic inclusions such as silicon, alumina, manganese sulfide and other non-metallic inclusions are also present in this steel.

St20Cr2CrMnMo has excellent mechanical properties, good heat treatment and corrosion resistance, especially nitridation and carburization, and good machinability and weldability. It is commonly used in quenching and tempering to improve the hardness, strength and wear resistance of the parts, and obtain better machinability of the parts. It is used to make parts for machine tools, automobiles, hot forging, mechanical machining and other industries, as well as high-voltage switch parts and long-life components and parts.