Samokhvalov G. The structure and properties of Low-carbon and Low-alloyed steels containing impurities of arsenic

Investigations object - physical, mechanical and technological properties, performances, corrosion resistance of Low-alloyed and Low-carbon steels, containing impurities of arsenic Subject of investigations–mechanism of phosphorus, sulphur and arsenic impurities influense on diffusion and solubility of carbon, dispersity pearlite rise. The basic method of investigations- X-raying analysis, electronic-microscopical, metalografic and corrosion resistance investigations, testes of mechanical properties. This thesis is devoted to the research of arsenic impurity influence on physical, mechanical and technological properties, performances, corrosion resistance of Low-alloyed and Low-carbon steels. The solution of this task is given, which made it possible to change the Limited content of arsenic in steels and to give practical recommendation on field application steels expansion, containing impurities of arsenic. It is shown experimentally by criterion of tongh-brittle change of iron-arsenic alloys and bycrack of steels 16Д, 15ХСНД and 20Г2АФпс, that the introduction of AS in a-iron up to 0,4 % and to steel up to 0,19 % doesn’t Lead to substantial decrease of their plasticity and ductility at the account of density dislocations inrease, subgrain grinding, dispersity pearlite rise. For the first time temperature range of phosphorus and arsenic influence on reversible brittleness of Low-alloyed and Low-carbon steels have been experimentally determined and distinguished. The temperature range of 525-565 oC is connected with intercrystalline inner absorbtion phosphorus, but 625-665 oC – arsenic. The obtained results of arsenic influence on physical and mechanical properties, performancies and corrosion resistance of Low-alloyed and Low-carbon steels on the ground of general analysis and conclusion a great number of industrial experiments, as well as theoretical conclusions enabled to recommend to raise upper Limited Level of arsenic content in ДСТУ 2651-94 (GOST 380-94) and GOST 19281-89 up to 0,15% for Largesection and structural shapes of carbon and Low-alloyed steel. Performance testings of pit prop made of steel 20Г2AФпс in the period of 2000-2005 in real conditions ”Yuzhnodonbasskaya №1” mill showed high reliability and durability along with good corrosion resistance.