Sulphur
Sulphur is an element that occurs in nature very often and also in elementary form. People have been using this element for over 7,000 years. During that time this element was used as a preservative and for disinfection. Today sulphur is used in many areas of industry.
Sulphur is an alloying element which, like lead, is used in the production of free-cutting steels. Sulphur forms inclusions of manganese sulphide in the metal structure, which increase chip breaking. As a result, sulphur-alloyed steels can be machined very well by turning, milling and drilling.
Sulphur has a negative influence on the rust resistance of steels. The influence of moisture can produce sulphur dioxide and sulphuric acid, which attack and corrode the alloy. For this reason it must be checked where steel grades with added sulphur are used.
The influence of sulphur on mechanical properties of steel:
| Property | Influence | Degree |
|---|---|---|
| Rust resistance | Decrease | - 1 |
| Hardness | no bearing | 0 |
| Strength | no bearing | 0 |
| Yield strength | no bearing | 0 |
| Elasticity | no bearing | 0 |
| Heat resistance | no bearing | 0 |
| Carbide formation | no bearing | 0 |
| Wear resistance | no bearing | 0 |
| Nitratability | no bearing | 0 |
| Strain | Decrease | - 1 |
| Reduction of area | Decrease | - 1 |
| Notched Impact Strength | Decrease | - 1 |
| Forgeability | Decrease | - 3 |
| Scaling | no bearing | 0 |
| Machinability | Improvement | + 3 |
Trivia
Sulphur was already known in China and Egypt 5,000 years before the calendar as a bleaching agent for textiles, disinfectant and as a medicine. The ancient Greeks used it to conserve wine. In ancient warfare it was used as a weapon for burning. The German monk Berthold Schwarz rediscovered black powder, which was already used by the Chinese in 1044. For a very long time it was the only known explosive material.
See also
Accompanying Elements
Steel does not only consist of iron and carbon. Other elements can influence the properties of steel.
Read moreAlloying Elements
There is a large number of different alloying elements. Each one influences the material properties.
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