Metallographic diagram of 08 steel (nitrocarburizing)

SAE 1070 steel – Nitrogen Carbon Diffusion Gold Phase Diagram

SAE 1070 steel is a low carbon steel that is widely used in the manufacture of a variety of components. It is classified as a nitriding steel, which means it can be used to create a hardened martensitic structure by diffusing nitrogen and carbon atoms into the steel matrix. This process increases wear resistance, fatigue resistance and overall strength. In order to make the most of the added strength, it is necessary to understand the gold phase diagram associated with SAE 1070 steel.

The gold phase diagram is a graph that illustrates the relationship between the hardness of a material and the amount of nitrogen and carbon it contains. It takes into account the temperature and time at which the nitride diffusion takes place. The diagram consists of an x-axis, which plots the amount of nitrogen and carbon, and a y-axis, which displays the hardness of the nitrided steel. In the case of SAE 1070, the graph shows that as the amount of nitrogen and carbon increases, the hardness of the steel also rises.

At low levels of nitrogen and carbon, the hardness of the steel is relatively low. This is due to the lack of extra strength provided by the diffusion process. As the amount of nitrogen and carbon is increased, the hardness of the steel increases, but not linearly. Rather, hardness increases exponentially until the peak hardness is achieved. After that, further increases in nitrogen and carbon result in a decrease in hardness.

The diagram can also be used to understand how long the nitriding process needs to take in order to achieve a particular hardness. As the amount of nitrogen and carbon is increased, the time required to achieve peak hardness also increases. In the case of SAE 1070 steel, a nitriding time of around two hours is suggested to achieve peak hardness. Longer nitriding times can result in the steel becoming over-diffused and creating a softer material.

Overall, the gold phase diagram associated with SAE 1070 steel is an important tool for engineers and manufacturers to utilize. It allows for the optimization of nitriding parameters in order to achieve maximum hardness and wear resistance. Additionally, it serves as a useful guide when examining data from nitrided materials.

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Steel 18Ni800 is a type of austenitic steel, which is a kind of stainless steel. It is composed of C, Mn, Cr, Ni, Mo, Si, and N with austenite structure. The characters of this steel are low-temperature toughness and mechanical properties, corrosion resistance and good weldability.

Metallographic observation of the 18Ni800 steel can be conducted under the microscope. The structure of the steel can be observed in the figure. There are ferrite and austenite phases in the stainless steel and inclusions of both size and shape.

Figure: The Metallographic Observation of 18Ni800 Steel

The martensite phase and ferrite phase can be seen in the metallographic observation and their relative amounts are 0.3:1. The austenitic phase can be seen composed of clusters of grains and large banded Widmanstatten structure. It is obvious that most of the structure is austenitic in nature. The amount of pearlite and ferrite can also be seen, which account for 0.3 and1 respectively.

The constituent elements shown in the observation are C, Mn, Cr, Ni, Mo and Si. C is mainly present as carbon concentrations on the boundaries between martensite and ferrite which probably derive from the separation of austenite. Mn is mainly distributed in fine and clear particles in austenite. Cr and Ni are mainly presented as aggregates of different sizes on the boundaries between ferrite and austenite. Mo and Si are mainly distributed in the austenite structure. N is mainly dispersed at the boundaries between ferrite, austenite and martensite.

All in all, 18Ni800 steel has an austenite structure with a ratio of 0.3:1 ferrite and martensite phase. The element compositions of C, Mn, Cr, Ni,Mo and Si are mainly scattered at the boundaries between austenite and other constituent phases, and N is mainly distributed on the surface of ferrite, austenite and martensite.