Metallographic diagram of Q235 steel (950℃ salt bath chromizing 6h)

Q235 steel is a common low-carbon alloy steel that is used in many applications. The mechanical properties of Q235 steel make it an ideal choice for various applications. At 950℃ salt bath tempering, Q235 steel undergoes a chromium precipitation process that takes 6 hours. This process can lead to increased strength, improved toughness, and improved corrosion resistance.

The general microstructure of Q235 steel contains ferrite and some pearlite. Due to the presence of certain alloying elements, such as manganese and nickel, Q235 steel can have some characteristics of austenite. This makes it suitable for a variety of applications. The addition of chromium to Q235 steel increases its strength and its ability to resist corrosion and wear.

In order to study the microstructure of Q235 steel after salt bath tempering at 950℃ for 6 hours, a metallographic study was conducted. The analysis consisted of preparing a small sample of the Q235 steel, mounting it on a glass slide, and polishing it. Once the sample was prepared, it was then examined under a polarized light microscope.

The micrographs obtained from the examination revealed that the Q235 steel contained a mix of ferrite, austenite and precipitates. The ferrite grains were surrounded by austenite grains, with a thin film of chromium precipitate particles coating the Austenite grain boundaries. The chromium precipitates were observed to have a hexagonal shape and had a higher refractive index than the surrounding ferrite and austenite grains, indicating the formation of chromium carbide particles.

The presence of the chromium precipitates and the high refractive index of the particles suggest that a passive layer was formed on the steel surface as a result of the tempering process. This passive layer aids in the corrosion protection of the steel and also contributes to improved wear resistance. The increased hardness of the steel due to the tempering process also improves the mechanical properties of the steel.

Overall, the findings from the metallographic study suggest that the salt bath tempering process at 950℃ for 6 hours enhanced the properties of the Q235 steel. The tempered steel had a more homogeneous microstructure compared to the untreated steel and had a greater resistance to wear and corrosion. These properties make it suitable for a variety of applications.

Q235 steel (salt-bath chromed for 6h at 950℃), also known as A3 mild steel, is one of the most commonly used structural steel materials in China. It is used in a wide variety of applications, including automotive parts, construction, tools and general engineering components.

Q235 steel has low carbon content and good welding properties, which makes it easy to work with. It has a good combination of strength and ductility, allowing it to be formed into various shapes. It also has good corrosion resistance-making it tolerable to different conditions and environments.

At 950℃, salt bath chroming was done on the Q235 steel, wherein the metal is immersed in a molten salt bath usually composed of sodium chloride or potassium chloride. This process creates a protective layer which enhances corrosion resistance and also lubricates the metal surface. By salt bath chroming the Q235 steel, its surface is also smoothened, which makes it easier to be formed into many shapes.

Microscopically, the grain size of the Q235 steel is found to be mainly polygonal with random orientation, which indicates a good metallurgical structure of the metal. It has a high number of dislocations, interstitials and grain boundaries, which further enhance its strength and ductility.

Overall, it can be concluded that salt bath chroming at 950℃ significantly enhances the properties of the Q235 steel, making it even more suitable for applications in automotive, construction and general engineering.