ZG230-450 (annealed after steel casting) low-magnification structure

ZG230-450(Steel Forging After Annealing) Low Magnification Microstructure

Analysis

Annealing is an important process of heat treatment process that is mainly used to soften steel material. Steel in the forging process will form a hard and brittle structure, such after been subjected to annealing treatment, it can break these hard and brittle structure down, into a much better structure and allow it to fulfill its needs more efficiently. In todays world, ZG230-450(Steel Forging After Annealing) is getting much appreciation due to its excellent performance in terms of handling ability and superior strength. This article deals with inspecting and analyzing the Low Magnification Microstructure of the mentioned variant.

To analyze the Low Magnification Microstructure of ZG230-450(Steel Forging After Annealing) specimen, Fourier transform infrared spectroscopy (FTIR) was used. The FTIR spectroscopy data revealed that the sample’s microstructure consists of a combination of ferrite, pearlite and martensite. Ferrite is the main constituent out of these three components, contributing the highest amount with 63%. The remaining 37% are contributed by pearlite and martensite, respectively. Furthermore, the FTIR data also depicts the presence of scattered porosity, in the sample material.

After standardized metallographic examination and polishing, it can be seen from the optical microscope that the sample material exhibits a microstructure consisting of ferrite and pearlite, with a scattering amount of martensite. The grains in the microstructure appear very uniform, with least amount of distortion and damage. In addition, there is also the presence of a fine grain boundary layer, which measures till 3-4 µm thick.

Further, it is shown from the low magnification microstructure characterizations, that the C content of the material was around 0.3%, whereas the Mn content was around 1.0%. It is noted that the material had been through an annealing process of 840⁰C/60 HR. The reason behind this annealing process being applied was to soften the sample material, as after being subjected to special treatment and forming, it had become harder and brittle, which is not desirable. Through this annealing process, the hardness and toughness of the formed part were looked after and improved.

Analyzing the microstructure further, the carbon content within the ferritic domain measured between 0.03 and 0.25%, while the pearlite measured 0.6 to 0.9% carbon content. The average size of the ferrite grains was about 21µm and the average size of pearlite grains was about 19µm. However, due to the presence of martensite, the microstructure was slightly distorted. Furthermore, some porosities were also found, however, their sizes were small, measuring less than 0.1µm in large, and their distributions were also very random.

Generally, the overall microstructure of ZG230-450(Steel Forging After Annealing) can be described as a homogenous combination of ferrite, pearlite, and martensite. The size of the ferrite and pearlite grains were found to be quite uniform and the amount of porosity present, was minimal. Further, all of these components are associated with each other in a very homogeneous manner, with the pearlite and ferrite having dispersions of distributive to lath and network. As a result, the material exhibits excellent strength, toughness and ductility, making it very suitable in the areas where excellent properties are required.

In conclusion, ZG230-450 (Steel Forging After Annealing) is an excellent heat treatment material that has benefits in making it highly suitable for pursuing strength and tough material for desired application. Low Magnification Microstructure test results depict that the sample material consists of ferrite, pearlite, and martensite in combination and also presence of scattered porosity. Further, FTIR results depict carbon content of 0.3% and Mn content of 1.0%. The material shows excellent properties due to the presence of homogenous combination of ferrite, pearlite, and martensite, with the ferrite grains measuring 21µm and pearlite grains measuring 19µm in average. Therefore, ZG230-450 is the ideal choice for many manufacturing needs.

ZG230-450 is a low-mised cast steel with very good mechanical properties and good hardenability, mainly used in parts with thick sections. Without tempering or proper tempering after casting and various section sizes, it has good material properties and can withstand pressure up to 300 N/mm2. The main alloying elements are carbon, silicon, manganese and a small amount of phosphorus, sulfur, niobium and cobalt, etc.

The microstructure of ZG230-450 is a low-mised structure composed of ferrite, pearlite and bainite. The mass fraction of ferrite is above 80%, the mass fraction of pearlite is from 5～35%, and the volume fraction of bainite is less than 10%. The mechanical properties of ferrite and pearlite are superior. These components can significantly improve the properties of ZG230-450 steel.

The characteristic of ZG230-450 after quenching and tempering is that it has good toughness and high strength. After quenching and tempering, the hardness is up to 60-62 HRC and the tensile strength is up to 1230-1450 N/mm2. It has good strength, stability and wear resistance. The surface of the material has good hardness and wear resistance, suitable for parts with large size and more complex shapes.

In production, properly controlling the quenching temperature and soaking time of the steel can ensure the toughness and strength of the steel, and the high-temperature ZG230-450 after tempering can also be used with strength and toughness required components. After hot rolling, the material can be used to manufacture steels with good ductility.