Metallographic diagram of ZG230-450 (annealed at 770°C)

The microstructure of ZG230-450 steel is an important component to ensure its practical application performance. It is commonly used in pressure vessels and other industries. After proper heat treatment, its microstructure mainly consists of two kinds of carbide, Martensite, Pearlite. In this report, ZG230-450 steel was studied to investigate its microstructure.

The sample was first heated to 960℃ and held for more than 1 hour, and then water quenched. Then the sample was tempered at 770℃ for 4 hours and cooled in the furnace gradually. The microstructure of ZG230-450 steel was examined by optical and scanning electron microscopes.

The surface of the sample displayed coarse, primary grains of pro-eutectoidal ferrite and cementite. Upon magnification, there were clear shoulders at the grain boundaries which were due to the formation of pearlite at the grain boundaries of the cementite and ferrite. The secondary carbide precipitations were observed within the ferrite grains. Further chemical analysis also supports that there is an undissolved carbide phase in the ferrite matrix.

The microstructure observed on the cross section of the sample showed that there was an even distribution of pearlitic transformation and secondary dissolution of cementite particles. It is easy to distinguish between proeutectoid cementite phase and the tempered cementite lattices. There were also granular martensite and refined ferrite which were finely distributed throughout the microstructure, providing further strength and toughness to the steel.

In conclusion, ZG230-450 steel is a typical medium and low alloy steel. After tempering, it can form a microstructure consisting of pro-eutectoid ferrite and pearlite which provides a good combination of strength and ductility. The presence of undissolved carbide phase and secondary dissolution of cementite also increases its toughness. Therefore, it is an ideal material for pressure vessels and other applications where a combination of good strength and high ductility is required.

EN AW-ZG230-450(770℃, Annealed) Alloys is a series of zinc-magnesium alloys with 6% magnesium and 0.25% zinc contents. The alloy is predominantly composed of Mg2Zn3 and MgZn2 phases with small amounts of MgZn4, Mg2Zn11, and Mg2Zn17 detected. The alloy features excellent mechanical strength, good corrosion resistance, high strength-to-weight ratio, and high thermal conductivity.

The microstructure of EN AW-ZG 230-450(770℃, Annealed) is composed mostly of refined oxide particles in a eutectic matrix. The alloy is characterized by a high-temperature annealing process at 770°C, during which the alloy cells undergo precipitation hardening. This yields a larger crystallite size of the alloy cells and improves the strength, ductility, and ductility-to-tensile strength ratio of the alloy.

EN AW-ZG230-450(770℃, Annealed) alloys also possess good mechanical and corrosion resistance as well as good oxidation resistance in corrosive environments such as acids, bases, and alkalis. The alloy also has a high strength-to-weight ratio, which makes it suitable for use in industries that require light-weighted structures. Additionally, its high thermal conductivity allows faster heat dissipation, thus reducing the thermal stress on components.

EN AW-ZG230-450(770℃, Annealed) alloys are primarily applied in the automotive, aerospace, and other industries. Their light-weightedness makes them ideal for use in fuel efficient vehicles, while their superior mechanical, thermal, and corrosion resistance make them a suitable material for the assembly of airplane and helicopter motor parts, as well as for various mechanical constructions. Moreover, the alloy can also be applied in other industries such as in the production of electrical components.