The effect of aging temperature on erosion corrosion （E-C） behavior of 17-4PH stainless steels in dilute sulphuric acid slurry containing solid particles was studied by using self-made rotating E-C apparatus. The ef...The effect of aging temperature on erosion corrosion （E-C） behavior of 17-4PH stainless steels in dilute sulphuric acid slurry containing solid particles was studied by using self-made rotating E-C apparatus. The effect of impact velocity on EC behavior of 17 4PH steels at different aging temperatures was analyzed. Surface micrographs of the specimens after E C test were observed by using scanning electron microscope （SEM）. The results showed that under the condition of the same solution heat treatment, when aging temperature ranged from 400 ℃ to 610℃, the hardness reached the highest value near the temperature 460℃. The characteristics of E-C for 17-4PH stainless steels at different aging temperatures were as follows： pure erosion （wear） was dominant, corrosion was subordinate and at the same time corrosion promoted erosion. The effect of aging temperature on E-C rate of 17-4PH steels was not significant at low impact velocity, but it was found that E-C resistance of 17-4PH steels aged near 460℃ was the most excellent due to the best precipitation strengthening effect of fine and dispersed e-Cu phase. With a prerequisite of appropriate corrosion resistance, the precipitation hardening could significantly improve the E-C resistance of the materials.展开更多
Effect of nitrogen content on the microstructure and erosion-corrosion (E-C) behavior of stainless steel (containing about 25%Cr,5%-6%Ni,and 1%-2%Mo) was investigated by using optical microscope(OM),potentiodynamic po...Effect of nitrogen content on the microstructure and erosion-corrosion (E-C) behavior of stainless steel (containing about 25%Cr,5%-6%Ni,and 1%-2%Mo) was investigated by using optical microscope(OM),potentiodynamic polarization curve and immersion method,a self-made rotating disk apparatus and scanning electron microscopy (SEM) and so on. The results show that with the increase of nitrogen content from 0 (no adding) to 0.485 wt.%,the Creq/Nieq ratio of the tested materials decreases from 4.14 to 1.23 and the ferrite volume percentage of the steel tested linearly decreases approximately from 90% to 10%. The effect of nitrogen content on polarization behavior of the studied steel was not signifi cant. All the passive current densities ( Ip) and pure corrosion rates (Vc) of the different N content specimens in the acidic solution (slurry containing 0.1 M H2SO4+0.06%Cl-+0.4%F-,the simplified zinc hydrometallurgy slurry) are too low and nearly negligible. Whereas the pure erosion rates (Ve ) of the four scenarios of the steels tested (N content,wt.%:N1,no adding; N2,0.143%; N3,0.289%; N4,0485%,respectively) are much higher than their Vc values. The V e values of the tested steels are in the order of N4 > N1 > N3 > N2,at the same time,the total weight loss rates (V t ) follow the order of N4 > N1 >N3 > N2,too. N2 steel consisting of approximately equal volume fractions of ferrite (α) and austenite (c) exhibits the most excellent E-C resistance and erosion resistance,while the stainless steels possessing the big difference between α phase and c phase,such as N1 steel nearly possessing single ferrite or N4 steel nearly possessing single austenite,show poorer E-C resistance and erosion resistance.展开更多
The effect of nonmetallic inclusions in the droplet of the stainless steel covered electrode on the porosity was researched.The result shows that the nonmetallic inclusions in the droplet are spherical,their compositi...The effect of nonmetallic inclusions in the droplet of the stainless steel covered electrode on the porosity was researched.The result shows that the nonmetallic inclusions in the droplet are spherical,their composition is different from the one of slag and the inclusions have the character of “inner formation”.When the ratio of rutile to ilmenite in the coated material is increased, the droplet becomes coarse, the content of nonmetallic inclusion in the droplet decreases,and the porosity sensitivity in the weld metal also decreases.When the ratio of fledspar to ilmenite in the coated material is increased, the droplet becomes fine,the content of nonmetallic inclusion in the droplet increases, and the porosity sensitivity in the weld metal increases. When the ratio of Fe_2O_3 to ilmenite in the coated material is increased, the droplet becomes fine, the content of nonmetallic inclusion decreases, while the porosity sensitivity does not reduce.展开更多
文摘The effect of aging temperature on erosion corrosion （E-C） behavior of 17-4PH stainless steels in dilute sulphuric acid slurry containing solid particles was studied by using self-made rotating E-C apparatus. The effect of impact velocity on EC behavior of 17 4PH steels at different aging temperatures was analyzed. Surface micrographs of the specimens after E C test were observed by using scanning electron microscope （SEM）. The results showed that under the condition of the same solution heat treatment, when aging temperature ranged from 400 ℃ to 610℃, the hardness reached the highest value near the temperature 460℃. The characteristics of E-C for 17-4PH stainless steels at different aging temperatures were as follows： pure erosion （wear） was dominant, corrosion was subordinate and at the same time corrosion promoted erosion. The effect of aging temperature on E-C rate of 17-4PH steels was not significant at low impact velocity, but it was found that E-C resistance of 17-4PH steels aged near 460℃ was the most excellent due to the best precipitation strengthening effect of fine and dispersed e-Cu phase. With a prerequisite of appropriate corrosion resistance, the precipitation hardening could significantly improve the E-C resistance of the materials.
基金supported by the postdoctoral foundation for Yituo Group Co., Ltd., P. R. China (No.TKJ2008-27)the doctoral foundation for Henan Polytechnic University, Henan (No. B2006-17)
文摘Effect of nitrogen content on the microstructure and erosion-corrosion (E-C) behavior of stainless steel (containing about 25%Cr,5%-6%Ni,and 1%-2%Mo) was investigated by using optical microscope(OM),potentiodynamic polarization curve and immersion method,a self-made rotating disk apparatus and scanning electron microscopy (SEM) and so on. The results show that with the increase of nitrogen content from 0 (no adding) to 0.485 wt.%,the Creq/Nieq ratio of the tested materials decreases from 4.14 to 1.23 and the ferrite volume percentage of the steel tested linearly decreases approximately from 90% to 10%. The effect of nitrogen content on polarization behavior of the studied steel was not signifi cant. All the passive current densities ( Ip) and pure corrosion rates (Vc) of the different N content specimens in the acidic solution (slurry containing 0.1 M H2SO4+0.06%Cl-+0.4%F-,the simplified zinc hydrometallurgy slurry) are too low and nearly negligible. Whereas the pure erosion rates (Ve ) of the four scenarios of the steels tested (N content,wt.%:N1,no adding; N2,0.143%; N3,0.289%; N4,0485%,respectively) are much higher than their Vc values. The V e values of the tested steels are in the order of N4 > N1 > N3 > N2,at the same time,the total weight loss rates (V t ) follow the order of N4 > N1 >N3 > N2,too. N2 steel consisting of approximately equal volume fractions of ferrite (α) and austenite (c) exhibits the most excellent E-C resistance and erosion resistance,while the stainless steels possessing the big difference between α phase and c phase,such as N1 steel nearly possessing single ferrite or N4 steel nearly possessing single austenite,show poorer E-C resistance and erosion resistance.
文摘The effect of nonmetallic inclusions in the droplet of the stainless steel covered electrode on the porosity was researched.The result shows that the nonmetallic inclusions in the droplet are spherical,their composition is different from the one of slag and the inclusions have the character of “inner formation”.When the ratio of rutile to ilmenite in the coated material is increased, the droplet becomes coarse, the content of nonmetallic inclusion in the droplet decreases,and the porosity sensitivity in the weld metal also decreases.When the ratio of fledspar to ilmenite in the coated material is increased, the droplet becomes fine,the content of nonmetallic inclusion in the droplet increases, and the porosity sensitivity in the weld metal increases. When the ratio of Fe_2O_3 to ilmenite in the coated material is increased, the droplet becomes fine, the content of nonmetallic inclusion decreases, while the porosity sensitivity does not reduce.
