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Structure and properties of forming austenitic X5CrNi18-9 stainless steel in a cold working

Ozgowicz W., Kurc A.

Journal of Achievements in Materials and Manufacturing Engineering

2009

Vol. 33, nr 1

19-26

Purpose: The aim of the paper is to analyze the influence of the degree of rolling reduction on the structure forming and changes of mechanical properties in cold-rolled sheet-metals of austenitic X5CrNi18-9 stainless steel. Design/methodology/approach: The examinations contained metallographic observations of the structure on a light microscope and on the scanning electron microscope (SEM), researches of mechanical properties in a static tensile test and microhardness measurements made by Vickers’s method. The analysis of the phase composition was carried out on the basis of X-ray researches. In the qualitative X-ray analysis the comparative method was applied. Fractographic tests of the fracture after the decohesion of samples in a static tensile test at room temperature were executed in a SEM. Findings: It has been found that plastic deformation in a cold working of austenitic stainless steel type X5CrNi18-9 induced in its structure martensitic transformation . › .’. The occurrence of martensite phases .’ in the investigated steel structure has an essential meaning in manufacturing process of forming sheet-metals from austenitic steel. Research limitations/implications: The X-ray phase analysis in particular permitted to disclose and identify the main phases on the structure of the investigated steel after its deformation within the range from 10% to 70%. Moreover, the results of the X-ray quantitative analysis allowed to determine the proportional part of martensite phases .` in the structure of investigated steel in the examined range of cold plastic deformation. Practical implications: The analysis of the obtained results permits to state that the amount of martensite phases .` in the investigated steel structure increases with the degree of deformation in the cold rolling. Besides, a good correlation was found between changes of the structure and the effects of investigations of the mechanical properties. Originality/value: Good correlation between changes of the structure and the effects of investigations of the mechanical properties in the austenitic X5CrNi18-9 stainless steel was found.

Przemiana fazowa z ferrytycznej w austenityczną w azotowanych bezniklowych stalach nierdzewnych

Tuliński M., Jurczyk K., Jurczyk M.

Inżynieria Materiałowa

2006

Vol. 27, nr 3

292-295

W niniejszej pracy podjęto próbę otrzymania nanokrystalicznej, bezniklowej, austenitycznej stali nierdzewnej metodami mechanicznej syntezy i azotowania. Opracowano skuteczną metodę wytwarzania takiej stali z proszków czystych metali Fe, Cr i Mo. Przemianę fazową z ferrytycznej w austenityczną na skutek azotowania materiału, potwierdzono analizą rentgenowską. Zmiany morfologii materiału na poszczególnych stadiach procesu śledzono wykorzystując skaningowy mikroskop elektronowy. Mikrotwardość otrzymanego materiału zbadano metodą Vickersa i jest ona prawie dwukrotnie większa niż dla materiału wytworzonego konwencjonalnymi metodami (odpowiednio 378 HV i 195 HV). Efekt ten jest związany z rozdrobnieniem struktury materiału i uzyskaniem nanostruktury.

In this work nanocrystalline nickel-free nitrogen-containing austenitic stainless steel were prepared by mechanical alloying, heat treatment and nitrogen absorption of mixture of elemental crystalline Fe, Cr and Mo powders. Phase transformation from ferritic to austenitic was confirmed by XRD analysis. Morphology was investigated by SEM technique. Microhardness of obtained material is almost two times higher (378 to 195 HV respectively) than in commercial microcrystalline austenitic stainless steel. This effect is directly connected with structure refinement.