GCr15SiMn (1100℃×20min+470℃×2s water cooling) metallographic diagram

Heat treatment of GCr15SiMn steel is a special process that helps to improve the performance of steel components. Heat treatment is the process of using heat to correct physical properties of a metal such as material strength, hardness, ductility and formability. GCr15SiMn steel is used in many applications such as bearings, springs, crankshafts, camshafts and gears, so the quality of the heat treatment is very important. The purpose of this study is to investigate the microstructure and mechanical properties of GCr15SiMn steel after heat treatment at different temperature and time conditions.

The specimen of GCr15SiMn steel used in this study had a diameter of 10mm and a length of 100mm. The specimens were preheated to 1100 ℃ for 20 minutes and then quenched in water at a temperature of 470 ℃ for 2 seconds. The quenched specimens were immediately cooled to room temperature for analysis.

The microstructure of the GCr15SiMn steel after heat treatment was observed using optical microscopy. The micrographs showed a martensitic structure with a high degree of homogeneity. The martensitic structure is composed of a small concentration of ferrite at the grain boundaries. The presence of ferrite in the matrix increased the hardness of the steel. The hardness of the GCr15SiMn steel was measured by a Vicker’s hardness test. The results showed that the hardness of the steel was greater than 50 HV.

The mechanical properties of the GCr15SiMn steel were determined by tensile testing. The results showed that the steel specimens had a yield strength of 545 MPa, an ultimate tensile strength of 860 MPa, an elongation of 11% and a Young’s modulus of 190 GPa. These values indicate that the GCr15SiMn steel has excellent mechanical properties after heat treatment.

The results of this study show that GCr15SiMn steel has improved mechanical properties after heat treatment at 1100℃×20min+470℃×2s. The heat treatment process can be used to improve the performance of GCr15SiMn steel components. The process can also be used to adjust the properties of steel components to meet the requirements of specific applications.

At 1100℃×20 minutes and 470℃×2 seconds with water quenching, the shape of the GCr15SiMn microstructure is Martensite and Austenite. The Martensite was lath-like, with acicular and irregular shape and size. The Austenite had a small amount of needle-like structure.

The average grain size of the martensite was about 10 to 12 microns, with some fine globular grains distributed in the Martensite lattice. Along with the Martensite granules, there were also some massive grains present in the martensite lattice which were round and scattered. The massive grains had an average diameter of about 25 to 30 microns.

At 470℃×2 seconds with water quenching, the microstructure presented three different phases: Austenite, Martensite and Carbide. The Austenite had the form of small, needle-like grains located in the center of large Martensite laths. The average grain size of the Austenite was about 5 microns. The Martensite structure was lath-like and had an average grain size of 8 microns. Lastly, the Carbide had an average grain size of 10 microns.

Overall, the Martensite, Austenite and Carbide structures in GCr15SiMn after 1100℃×20 minutes and 470℃×2 seconds are lath-like, needle-like, and globular, respectively. The microscope view of these grains shows that all three structures present consistent size and shapes. Thus, it can be concluded that the GCr15SiMn obtained after that quenching process has good metallurgical characteristics.