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How Does Carbon & Sulfur Analyzer Analyze C, S Elements
2020 07 20

How Does Carbon & Sulfur Analyzer Analyze C, S Elements

How does Carbon & Sulfur analyzer analyze C and S elements?

The carbon and sulfur elements are important to determine the quality and specification of the steel.

When the carbon content above 1.70% can be called cast iron, below 1.7% is called steel. Steel with carbon content between 0.25% and 0.60% is called medium-carbon steel, steel with carbon content less than 0.25% is called low-carbon steel, and steel with carbon content less than 0.25% is called carbon steel. The content of less than 0.04% is called industrial pure iron.

Crbon plays an important role in the performance of a steel analyzer, as the carbon content increases, the hardness and strength of the steel increases, and its toughness and plasticity increase. If the carbon content decreases, the hardness and strength decrease, while the toughness and plasticity increase.

It is widely used in metallurgy, foundry, machinery, vehicle, ore, and other industries. Moreover, it can also be easily and quickly analyzed and tested at the stages of raw material acceptance, pre-furnace analysis and finished product inspection. The presence of sulfur in steel will deteriorate the quality of steel, reduce its mechanical properties and corrosion resistance, weldability. In particular, the sulfur in steel, if present in the state of iron sulfide, due to its low melting point(about 1000℃), will cause the steel “Hot brittle” phenomenon, that is , thermal deformation, high temperature work to produce cracks, affecting the quality and life of the product.

Therefore, the lower the sulfur content in steel, the better. General requirements, ordinary steel sulfur content of less than 0.050%, tool steel in the sulfur content of less than 0.045%, the sulfur content of high quality steel is less than 0.020%. Given the importance of carbon and sulfur content to the quality and performance of steel, it is important to detect the carbon and sulfur content in steel, So the carbon and sulfur content is important.

There are several general methods of measurement

1. Infrared photometry 

The carbon and sulfur in the specimen were oxidized to carbon dioxide and sulfur dioxide gas by high temperature heating under oxygen-rich conditions. The gas enters the corresponding absorption cell after treatment and absorbs the corresponing infrared radtiation, which is forwarded as a signal by the detector and output by computer processing. This method has the characteristics of accuracy, speed and high sensitivity, which can be used for both high and low carbon and sulfur content. Carbon & Sulfur Analyzer using this method has a higher degree of automation and is suitable for occasions with higher analytical accuracy requirements.

2. Volumetric method

Commonly used methods are gas volume and non-aqueous titration for carbon, iodine and acid-base titration for sulfur. In particular, the gas volume method to measure carbon, iodine amount of legal sulfur, both fast and accurate, the lower limit of carbon content of 0.050%, the lower limit of sulfur content for the 0.005% for most occasions.

3. Weighting method

Carbon dioxide is absorbed by alkaline asbestos and the carbon content is determined from the “increment”. Sulfur is measured by the wet method, in which the sample is decomposed and oxidized by acid, transformed into sulfate, and then barium chloride is added to the hydrochloric acid medium to generate the sulfur contetn. Barium sulfate, precipitated, filtered, washed, burned, weighed and finally calculated to give the sulfur content. The disadvantage of the gravimetric method is that it is slow, it is not suitable for onsite carbon and sulfur analysis in companies, while the advantage is that it has a high degree of accuracy and is suitable for standard laboratories and reserach institutions.

4. Electrical conductivity

The conductivity method for the determination of carbon and sulfur is characterized by accuracy, rapidity and sensitivity, with the disadvantage of a narrow measurment range and the use of more reagents. This method is suitable for the dtermination of low carbon and low sulfur.

5. For the determination of carbon and sulfur content in metals, there are ICP method, direct reading spectrometry, X-ray fluorescence method, mass spectrometry, chromatography, activation analysis, etc., each of which has its own advantage and scope of application.


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