Carbon element is the basic element in iron and steel and the carbon element content can serve a  reference to distinguish iron from steel. Generally, those with carbon element content <1.7% are steel, and those >1.7% are iron.

 

The carbon in iron and steel presents as compound state and free state. The most carbon in steel exists in the state of compound, while in iron, in the free state. The sum of compound carbon and free carbon is called the total carbon.

 

Carbon content can directly affect the property of steel. When the carbon content is high, the hardness and intensity of steel increases, while its melting point, plasticity and ductility decrease, to make the steel difficult to be processed. The intensity and hardness of iron increase with the carbon content.

sulfur in steel is a kind of detrimental element to cause the hot shortness for steel, decease its mechanical performance. It is unfavorable to corrosion resistance and weldability of steel. In order to promote the machinability of steel, the content of sulfur can be increased. However, the sulfur content is generally low in the alloy.

 

The measurement of carbon element is generally computed by total carbon, with common analysis methods of gas capacity method and nonaqueous titration method. (as per GB/T 223.69-1997)

 

The sample is burnt in 1,250¡æ oxygen flow, loaded and borne by far infrared carbon sulfur crucibles, converting carbon oxygen into carbon dioxide, and the mixed gas after burning is collected through the gas remained after desulfuration into the measurement cylinder to meter volume and then absorbed by potassium hydroxide to test the gas volume difference and work out the carbon content through pressure sensor.

 

The measurement of sulfur element is usually computed by iodometry and acid-base titration method. (as per GB/T 223.68-1997)

 

The sample is burnt in 1,250¡æ oxygen flow, loaded and borne by far infrared carbon sulfur crucibles, converting sulfur oxygen into sulfur dioxide gas, and the sulfur dioxide gas after burning absorbed by water produces sulfurous acid. Employ the iodine solution to titrate amylum in the iodine solution to indicate end point color and titrate the iodine solution volume difference to work out the sulfur content through pressure sensor.