Papers by Author: Long Mei Wang

Abstract: The anodic polarization curves of 2Cr13 stainless steel with various RE contents in 3.5% NaCl neutral solutions have been measured by electrochemical methods. The effect of Ce on pitting corrosion resistance of 2Cr13 stainless steel has been studied by the metallographic examination. The results show that sulfide and other irregular inclusions are modified to round or oval-shaped Ce2O2S and CeS after adding Ce to 2Cr13 stainless steel.Ce makes sulfide, and other irregular inclusions change to dispersed round or oval-shaped Ce inclusions, effectively inhibits the occurrence of pitting corrosion, thereby enhancing the corrosion resistance of 2Cr13 stainless steel.

Abstract: A primary study on the resistance to high-temperature-oxidation of 430 ferrite stainless steel and its oxidation process before and after the addition of RE elements was reported. Results show that the oxidation resistance of 430 ferrite stainless steel after adding RE is indeed great. The value of oxidation rate of Sample 1 (without adding RE) is 2.87 times higher than Sample 2, respectively at 1423K after oxidizeing for totally 144h. And the dense and adherent Cr2O3 scale and FeCr2O4 scale are formed and played the protection role to the 430 ferrite stainless steel. In the internal oxidation layer, the pinning effect of silicon dioxide is strengthened by RE.

Abstract: The oxidation resistance of FeCrNi heat-resisting steel at 1150°C and 1200°C is analyzed and studied using XRD, SEM and EDS techniques. The results show that the oxidation resistance of the heat-resisting steel is improved remarkably after adding yttrium. The value of oxidation rate of experimental Sample 1 (without adding Y) is 3.25 times and 1.56 times higher than Sample 2, respectively at 1150°C and 1200°C after oxidizeing for totally 144h. On the surface of the heat-resisting steel containing Y, the dense and adherent Cr₂O₃ scale and FeCr₂O₄ scale are formed and played the protection role. In the internal oxidation layer, the pinning effect of silicon dioxide is strengthened by Y, and Y has a pining effect directly.

Abstract: In this paper, the effect of N addition on mechanical properties of 21Cr-11Ni austenitic heat-resisting stainless steel was investigated. Scanning electron microscopy was used to study the fracture surfaces in the steels. N in 21Cr–11Ni heat-resisting steel can play a role of stabling austenite and ensuring the structure and mechanical properties in high temperatures. Fracture is changed from cleavage to ductile fracture to 21Cr–11Ni heat-resisting steel, and the strength of test steel are improved at room temperature by adding N, the tensile strength is increased by 8.33%. And the creep rupture strength is improved. The fracture time of the steel containing 0.2% N is 3.2 times higher than the steel containing 0.14% N at 1144K.

Abstract: The effect of Ce on modifying inclusions of 2Cr13 stainless steel was studied by metallographic examination, SEM and electron spectroscopy. Thermodynamic calculation was used to analyze the formation of RE inclusions in 2Cr13 stainless steel. The result shows that MnS can be entirely replaced by Ce2O2S and CeS that are spherical.

Abstract: The anodic polarization curves of 2205 duplex stainless steel with various RE contents in 3.5% NaCl neutral solutions have been measured by electrochemical methods, The effect of rare earth on pitting corrosion resistance of 2205 duplex stainless steel has been studied by the metallographic examination. The results show that RE can effectively depress pitting corrosion, while the irregular inclusions of Al2O3, sulfide in the shape of clump are transformed into tiny dispersive round or oval RE inclusions, and it plays a good role in pitting resistance.

Abstract: The effect of rare earth metals on modifying inclusions of 2205 duplex stainless steel was studied by metallographic examination, SEM and electron spectroscopy. Thermodynamic calculation was used to analyze the formation of RE inclusions in 2205 duplex stainless steel. According to the composition of 2205 duplex stainless steel liquid and thermodynamic data, it may calculate and predict the kinds of RE inclusions. And the result shows that aluminosilicate complex inclusion and sulfide inclusion can be entirely replaced by RE2O2S and RES that are spherical.

Abstract: The effects of rare earth metals on the inclusions and the mechanical properties of 2205 duplex stainless steel were studied by metallographic examination, scanning electron microscope (SEM) and energy spectrum analysis. The results show that the morphologies and sizes of non-metallic inclusions in 2205 duplex stainless steel are changed, and rare earth metals played a very good role of modifying inclusions. The fracture mode of 2205 duplex stainless steel is typical cleavage fracture, but quasi-cleavage and dimple fracture after adding RE into the steel, and the spherical inclusions of rare earth oxysulfide in the dimple are the main factors for this transformation. The transverse impact toughness of 2205 duplex stainless steel is improved obviously by RE. In comparison with 2205 duplex stainless steel without RE, the transverse impact toughness of 2205 duplex stainless steel with RE is increased 20.49% at -40°C, and the room temperature strength are improved, the elongation and reduction of area have been improved 11.67%, 24.55% respectively.

Abstract: The effect of rare earth metals on inclusions and impact toughness of 2205 duplex stainless steel were studied by SEM and electron spectroscopy. Thermodynamic calculation was used to analyze the formation of RE inclusions in 2205 duplex stainless steel. The result shows that aluminosilicate compound inclusion and sulfide inclusion can be entirely replaced by RE2O2S and RES. Fracture is changed from cleavage to ductile fracture by adding RE to the 2205 duplex stainless steel, and the spherical rare earth oxysulfide inclusions-RE2O2S in the dimple are the main factors. The transverse impact value of 2205 duplex stainless stainless steel has been improved obviously by RE. The transverse impact value of RE-2205 is increased 20.49% at the temperature of -40°C, comparing with 0RE-2205.