| dc.description.abstract | This study investigated the effects of mechanical properties and corrosion resistance of EN series and low nickel stainless steels in as-cast, thermal cycling, and heat-treated steels, respectively. EN series and low nickel stainless steel tensile test were used in the experiment, divided into as-cast, three thermal cycles, ten thermal cycles and heat treatment, and then processed into tensile test according to JIS Z2201 13B specifications for stretching and volume measurement. Subsequently,analysed the effect of as-cast and thermal cycling and heat treatment on the microstructure and mechanical properties of the material.
Grinded and polished the longitudinal section of the sample after the tensile test, observed the microstructure of the base and precipitates with an optical microscope (OM), and analyzed the number, size and distribution of carbide particles using image analysis software to research carbide particles effect on the mechanical properties of the alloy. Through scanning electron microscopy (SEM), determined the type of precipitate, used the diffraction peak produced by X-ray powder diffractometer (XRD) to confirm the type of precipitate, and use the potentiostat to analyze the corrosion resistance and the speed of the corrosion rate.
The experimental results showed that all the test bars meet the requirements of the specification, among which the LNSS test bar 8 is the most prominent at room temperature mechanical properties (YS: 292MPa, UTS: 499MPa and EL: 29%); the high temperature mechanical properties are the best with EN1.4848 (30.9 MPa) , UTS: 32MPa and EL: 51%); What’s more, after three thermal cycles, the mechanical properties of high temperature showed an increasing trend; after ten thermal cycles, the mechanical properties of EN1.4849 all improved.The main reason is that after three thermal cycles,the total number of carbide particles first increases and then decreases. After thermal cycling, carbides precipitate at the base or grain boundaries, which will produce precipitation free zone (PFZ).PFZ has the greatest influence on the mechanical properties and corrosion resistance of EN series and low nickel stainless steel, and the continuous distribution of precipitates on the grain boundaries will reduce the elongation and toughness of the stainless steel. | en_US |