Analysis of features of stainless steels in dissimilar welded joints in chloride inducted corrosion

5th ModTech International Conference - Modern Technologies in Industrial Engineering

Topolska, S.^1 ; Labanowski, J.^2

Silesian University of Technology, Faculty of Mechanical Engineering, Institute of Engineering Materials and Biomaterials, Konarskiego 18A, Gliwice

44-100, Poland^1

Gdask University of Technology, Faculty of Mechanical Engineering, Department of Materials and Welding Engineering, G. Narutowicza 11/12, Gdask

80-233, Poland^2

关键词: Austenitic microstructure;    Chemical compositions;    Crack resistance;    Lower temperatures;    Partial transformation;    Stable structures;    Strength property;    Two-phase structures;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/227/1/012130/pdf
DOI  :  10.1088/1757-899X/227/1/012130

来源: IOP

【 摘 要 】

Stainless steels of femtic-austenitic microstructure that means the duplex Cr-Ni-Mo steels, in comparison with austenitic steel includes less expensive nickel and has much better mechanical properties with good formability and corrosion resistance, even in environments containing chloride ions. Similar share of high chromium ferrite and austenite, which is characterized by high ductility, determines that the duplex steels have good crack resistance at temperatures up to approximately -40°C. The steels containing approximately 22% Cr, 5% Ni, 3% Mo and 0.2% N crystallizes as a solid solution δ, partially transforming from the temperature of about 1200°C to 850°C into the phase α. The stable structure of considered steels, at temperatures above 850°C, is ferrite, and at lower temperatures the mixture of phase γ+α +σ. The two-phase structure α+γ the duplex steel obtains after hyperquenching at the temperature of stability of the mixture of α+γ phases, and the share of the phases depends on the hyper quenching attributes. Hyperquenching in water, with a temperature close to 1200°C, ensures the instance in the microstructure of the steel a large share of ferrite and a small share of the high chromium austenite. This causes the increase of strength properties and reducing the plasticity of the steel and its resistance ability to cracking and corrosion. Slower cooling from the mentioned temperature, for example in the air, enables the partial transformation of the a phase into the γ one (α → γ) and increasing the share of austenite in the steel structure. It leads to improvement of plasticity properties. In the paper are presented the results of investigations of heteronymous welded joints of duplex steel and austenitic one. The results include the relation between the chemical composition of steels and their weldability.