Metallographic diagram of GCr15 (830℃×1h water quenching, 500℃×1h water cooling) steel

High chromium bearing steel GCr15 (830℃×1h water quenching, 500℃×1h water cooling) has higher wear resistance, better fatigue strength and better heat treatment performance than ordinary structural steel. GCr15 is widely used in various field of mechanical parts such as bearing, poultry shearing post, connecting rod and spring. In order to meet the requirements of different industry application, the heat treatment process of GCr15 steel is also varied.

GCr15 steel is usually subjected to quenching, tempering and other heat treatment processes before being used as mechanical components. Through quenching and tempering treatment, the matrix of GCr15 steel can reach the metallographic structure of the tempered sorbite, and make the performance of GCr15 steel further improved, which can further improve the fatigue strength and wear toughness of the steel.

First of all, the GCr15 steel should be heated uniformly to 830℃ for 1 hour and then quickly quenched in water which makes the steel matrix reach the martensitic state. After quenching, the GCr15 steel toughing treatment should be conducted by heating at 500℃ for 1 hour and then cooled in the water. Through tempering, the uneven hardness caused by quenching can be eliminated, meanwhile the toughness of GCr15 steel could be improved and its fatigue strength could be enhanced.

The microstructure of GCr15 steel can be observed under a metallographic microscope after being quenching and tempering, which will show more martensite structure transformation and acicular martensite. This martensite structure can ensure the good comprehensive performance of GCr15 steel.

In the heat treatment process of GCr15 steel, quenching and tempering are two important processes. Quenching can result in the martensitic structure of the matrix, and by tempering the hardness and brittleness of the steel can be balanced. After quenching and tempering, GCr15 steel can gain a good comprehensive performance, with good wear resistance, fatigue strength, toughness and strength. Therefore, it is very important to strictly follow the process requirements of 830℃×1h water quenching and 500℃×1h water cooling to make sure the GCr15 steel has a good performance.

A ferrite pearlitic GCr15 Steel is a low carbon, chromium-containing steel which contains approximately 0.85 % Carbon, 1.0 % Chromium and 1.5 % Manganese. It is usually used in bearing components, rolling contact parts and other components where superior wear resistance is important. The following describes the metallographic examination of a ferrite pearlitic GCr15 Steel that was subjected to an 830 °C (1525 °F) 1 hour water quench, followed by a 500 °C (932 °F) 1 hour water quench.

The metallographic examination revealed a uniform microstructure that showed a mostly ferritic matrix containing lath-shaped particles of pearlite interspersed throughout. The pearlite particles showed a finely divided, thin layer on the surface. Due to the high temperatures employed during quenching, a faint reddish-brown color was observed on the surface of the steel.

Chemical analysis revealed that the steel contained 0.846 % C, 1.04 % Cr and 1.5 % Mn. The mechanical properties of the steel were evaluated, with a material hardness of 41.7 Rockwell C---an indication that the steel had been properly hardened and tempered.

In conclusion, the ferrite-pearlite GCr15 Steel used in this instance was an excellent candidate for use in bearing components, rolling contact parts and other components where superior wear resistance is required. The quenching process employed was effective in hardening the steel to the desired hardness, while allowing the microstructure to retain the appropriate combination of ferrite and pearlite. Furthermore, the chemical composition of the steel was within the accepted values for both GCr15 and H-112 grade steels.