The five element is the most important element in the iron and steel is the most basic element, the content of the five elements of a direct impact on the performance and grades of metal, so it is particularly important to detect the five elements. The following are the five elements of the role and inspection basis:
The role of carbon element in steel is that it is the main basis for distinguishing between steel or iron, and the amount of carbon containing more than one point seven percent is iron, which is less than one point seven percent of the said steel. A combination of state and free state of carbon in steel. Steel carbon most the state exists, in the iron carbon in the free state exists, the combined carbon and free carbon and total carbon. Carbon content directly affects the performance of steel, while the carbon content is high, the hardness and strength of the steel increases, but its melting point, ductility and ductility decrease, so that steel is difficult to process. Iron strength and hardness increase with increasing carbon.
Sulfur is a harmful element in steel. It makes steel hot shortness phenomenon, reduce the mechanical properties of the steel, steel resistance corrosion and can be welded adverse, in free cutting steel, in order to improve the machinability of steels, can increase the sulfur content, in general alloy sulfur content are low. Determination of elemental carbon are generally for the determination of total carbon content, the commonly used analytical methods have gas volumetric method and non water titration (according to the standard of GB / T 223.69-1997), specimen in 1250 DEG C oxygen flow in combustion, the carbon dioxide into carbon dioxide, after the combustion of mixed gas removal of sulfur after left more than gas collection in pump constant volume and then by potassium hydroxide absorption, the determination of the volume of a gas, by a pressure sensor for the carbon content. Determination of sulfur element is generally used by the method of iodine or acid-base titration method (based on 223.68-1997 GB/T standard), the test sample in the oxygen flow at 1250 C, so that sulfur dioxide gas, sulfur dioxide gas after burning, and then use water to generate sub sulfuric acid, iodine liquid in the starch indicator of the end color, the volume of the titration of iodine, sulfur content by pressure sensor.
Manganese is one of the important elements in the alloy, it is usually a solid solution and compound form. Manganese is a good agent and a desulfurization agent, can reduce the thermal brittleness caused by sulfur, and then improve the thermal performance of steel, improve the workability of steel. Increase the manganese content, can improve the strength and hardness of steel. Determination of manganese, commonly used analytical methods have silver -- over oxidation of manganese sulfate ammonium oxidation photometric method (according to the standard of GB / T 223.63-1988) sample dissolved in hydrochloric acid. In a certain pH conditions and silver nitrate as catalyst, ammonium persulfate to permanganate absorbance determination.
The phosphorus in the steel are present in solid solution phosphides, sometimes assumes phosphate inclusions exist in the form of. Phosphorus in steel can improve the tensile strength and corrosion resistance of the steel, improve the cutting performance of steel, but also can reduce the high temperature performance and increase the brittleness, infrared carbon sulfur analyzer, which affects the ductility and toughness of steel. The phosphorus is a harmful element in steel. Determination of the phosphorus, the commonly used analytical methods with sodium fluoride and stannous chloride molybdenum blue method (according to the standard of GB / T 223.61-1988) in acidic solution, with potassium permanganate oxidation, metaphosphate oxidized to phosphate, and ammonium molybdate formed molybdenum heteropoly acid, stannous chloride reduction to molybdenum blue. Determination of the absorbance.
Silicon element is a useful element in steel, it can enhance the tensile strength, elasticity, acid resistance, heat resistance and corrosion resistance of the steel, and can increase the resistance coefficient of steel, and it is also an effective agent for steel. Silicon is mainly in the form of iron in steel. Determination of silicon, the commonly used analytical method with ferrous reduction -- silicon molybdenum blue photometric method (according to the standard of GB / T 223.5-1997) in acidic solution, the silicic acid and ammonium molybdate formed yellow silicon molybdenum heteropoly acid complexes, with stannous chloride reduction into silicon molybdenum blue, and its absorbance was measured.
