What is Sulfur

Sulfur is a non-metallic element. It is one of the elements of the oxygen group and is located in the third period of the periodic table.

Monomorphic sulfur is usually a yellow crystal. There are many different isomers of sulfur monomers, including rhombohedral sulfur, monoclinic sulfur, and elastic sulfur. Elemental sulfur is usually found in nature as a sulfide, sulfate, or monomer. Sulfur monomers are insoluble in water, slightly soluble in ethanol, and readily soluble in carbon disulfide.

Sulfur is an important constituent of proteins in the human body and is important for human life activities. Sulfur is mainly used in the production of fertilizers, gunpowder, lubricants, insecticides and antifungal agents.

Sulfur dioxide generated by the combustion of sulfur and sulfur-containing ores combines with water in the air to form sulfurous acid. Sulfite reacts chemically with oxygen in the air to form sulfuric acid, resulting in sulfuric acid rain.

For humans, simple sulfur is usually non-toxic and harmless. Other sulfur-containing compounds, on the other hand, may be somewhat toxic. Sulfur compounds are generally more toxic.

The Effect of Sulfur on Superalloys

Unlike other trace elements, sulfur is a completely harmful element in superalloys.

First, sulfur in superalloys is polarized at grain or phase boundaries and weakens them. This segregation becomes a conduit for crack initiation and extension. When the sulfur content is high, the harm produced by segregation is further increased.

Secondly, sulfur prevents solidification of the alloy and affects the solidification process. It causes segregation of other elements and precipitation of harmful phases.

When the sulfur content is greater than 0.009%, the room and high temperature transient properties of the alloy decrease sharply with increasing sulfur content, and the durability and fatigue properties also decrease sharply.

When the alloy is stretched, cracks are mainly generated at grain boundaries. Sulfur is easily polarized at grain boundaries. As the sulfur content increases, the sulfur at grain boundaries also increases. When the sulfur content is greater than 0.009%, the grain boundaries are greatly weakened. This causes a sharp decrease in the strength of the alloy.

In addition, at high temperatures, the temperature promotes the thermal activation of sulfur. This causes a portion of the sulfur to diffuse into the grain boundaries, resulting in further weakening of the grain boundaries at elevated temperatures. As a result, the effect of the decrease in high temperature tensile properties with increasing sulfur is amplified.

Finally, changes in sulfur content also have a significant effect on the creep-fatigue interaction. At low sulfur content, it is a strengthening effect and the cycle endurance strength is higher than the monotonic endurance strength, while at high sulfur content, the weakening effect causes the cycle endurance strength to be lower than the monotonic endurance strength.

Conclusion

Sulfur is a non-metallic element. It is regarded as a harmful element in superalloys. It reduces the strength, transient properties, durability and creep-fatigue interaction of the alloy.

We manufacture a wide range of superalloys in accordance with strict standards and can strictly control the sulfur content. Please contact us for any inquiries regarding superalloys.

2023.07.18