The investigation on the behavior of RE in microalloyed steel containing Nb and Ti indicates RE still have the effect of purifying molten steel and metamorphose inclusions even when the composition of S is pretty low(...The investigation on the behavior of RE in microalloyed steel containing Nb and Ti indicates RE still have the effect of purifying molten steel and metamorphose inclusions even when the composition of S is pretty low(S<0 003%). The optimum performance of the experimental steels can be obtained when w RE / w O+S is controlled around 3 9. The content of solid solution RE can reach 1×10 -5 ～1×10 -4 order of magnitude in ultra low sulfur steel. The additions of RE can reduce the segregation of S and P at the grain boundary, delay the dynamic recrystallization, refine the grain and second phase particles, and promote the precipitation of (Nb, Ti)(C, N). RE also exhibit the microalloying effect in steel.展开更多
Studies were made of the symmetric tensile-compressive low cycle fatigue behaviour and the influence of dynamic strain aging(DSA)pre-treatment of 18-8 austenitic stainless steel. Within the testing amplitude range of ...Studies were made of the symmetric tensile-compressive low cycle fatigue behaviour and the influence of dynamic strain aging(DSA)pre-treatment of 18-8 austenitic stainless steel. Within the testing amplitude range of strain.±0.5 % to±1.5 %,the three processes of cyclic hardening,cyclic saturation and cyclic softening were observed.In the same amplitude of strain,the peak stress of the samples pre-treated by DSA is higher than that of solid-solu- tion and cold working pre-treatment,but no remarkable differences of the fatigue lives of them were found.TEM observation shows that the uniform and stable dislocation networks with high density form after DSA pre-treatment,which increases the cyclic peak stress.The cyclic softening results from the low dislocation density and elongated cell structure with low energy.展开更多
The influence of rare earth lanthanum and cerium on impact property of structural alloy steel with extra low sulfur and oxygen was studied by impact test and microanalysis. The results showed that rare earths increase...The influence of rare earth lanthanum and cerium on impact property of structural alloy steel with extra low sulfur and oxygen was studied by impact test and microanalysis. The results showed that rare earths increased impact power of the steel when their contents were about 0.005%. Proper addition of rare earths could purify grain boundaries and decrease amount of inclusions, and reduced the possibility of crack growth along grain boundaries and through inclusions. Therefore, such steel could absorb more crack growth energy while it was impacted. However, if the content of rare earths is excessive, the grain boundary would be weakened and brittle-hard phosphates and Fe-RE intermetallic would be formed, which worsened impact toughness of steel.展开更多
The effect of [S] on strength and toughness of low alloy steel plates inwhich sum of [P], [N], T[O] is less than 8x10^(-5) and the effect of T[O] on strength and toughnessof the steel plates in which sum of [S], [P], ...The effect of [S] on strength and toughness of low alloy steel plates inwhich sum of [P], [N], T[O] is less than 8x10^(-5) and the effect of T[O] on strength and toughnessof the steel plates in which sum of [S], [P], [N] is less than 7x10^(-5) were investigated. It isfound that the strength of the steel plates decreases with increasing [S] content when [S] is lessthan 4x10^(-5). When [S] varies within the range of 4x10^(-5)-1.2x10^(-4), [S] has no significanteffect on strength of the steel. The strength of the steel plates increases with increasing T[O]content when T[O] is less than 30x10^(-6), but decreases with increasing T[O] when T[O] is more than3x10^(-5). The difference between the LETT in plate length direction and LETT in width directiondecreases with decreasing [S] content. However, even when [S] is decreased to 9x10^(-6), thedifference of the LETT is still 16℃. When T[O] varies between 1.8x10^(-5) and 5.2x10^(-5), the lowtemperature impact toughness of the steel plates slowly decreases with T[O] increasing. When T[O]increases to more than 5.2x10^(-5), the low temperature toughness of the steel rapidly decreaseswith increasing T[O] content.展开更多
在宝钢炼钢厂300 t RH-KTB上进行了超低碳超低硫钢的预熔渣深脱硫试验。试验共12炉,预熔渣加入量为4 kg/t。试验结果表明,在RH平均初始w(S)为42.1×10-6条件下,处理终点平均w(S)达到30×10-6,最低w(S)达到22×10-6,最高脱...在宝钢炼钢厂300 t RH-KTB上进行了超低碳超低硫钢的预熔渣深脱硫试验。试验共12炉,预熔渣加入量为4 kg/t。试验结果表明,在RH平均初始w(S)为42.1×10-6条件下,处理终点平均w(S)达到30×10-6,最低w(S)达到22×10-6,最高脱硫率达到36.6%,平均脱硫率达到28.6%,取得了较好的深脱硫效果。采用预熔渣处理过程钢中w(TO)及w(N)均有所降低。试验炉次钢中最低w(TO)为12×10-6,平均w(TO)为13.3×10-6,最低w(N)为11×10-6,平均w(N)为13.8×10-6。RH终点钢中的夹杂物主要是Al2O3,95.1%的夹杂物小于5μm。展开更多
In order to reduce the content of oxygen and sulfur in steel, and produce low-sulfur and low-oxygen steel, study on slag has been carried out. Refining slag system of CaO-SiO2-Al2O3 is put forward with the considerati...In order to reduce the content of oxygen and sulfur in steel, and produce low-sulfur and low-oxygen steel, study on slag has been carried out. Refining slag system of CaO-SiO2-Al2O3 is put forward with the consideration of slag amount from converter, oxidizability of slag and activity of oxygen in molten steel. On this basis, refining slagging system for low-sulfur and low-oxygen steel has been developed combined with the modification of slag from converter and composition control of refining slag in LF treatment process. The results show that oxygen content is not more than 15×10-6, as well as sulfur content is as low as 0.005% in tube blank steel. And it achieves the production of low-sulfur and low-oxygen steel.展开更多
Based on the fact of long period deep desulfurization treatment in LF,the relationships among top slag constituent in LF,molten steel constituent,stirring ability of blowing argon,molten steel temperature and desulphu...Based on the fact of long period deep desulfurization treatment in LF,the relationships among top slag constituent in LF,molten steel constituent,stirring ability of blowing argon,molten steel temperature and desulphurization rate were analyzed.Through the experiments,the parameters about treatment technology of top slag in LF,the [Als] content in molten steel,slag charge match,molten steel temperature and the argon flow for stirring have been optimized.The desulphurization treatment period in LF can be shortened by 5～8 minutes.The target sulfur content in molten steel can be controlled below 30 ppm within one LF treatment period which is only 36 minutes.The LF treatment period of ultra-low sulfur steel can primarily match with the continuous casting period,multi-heat continuous casting can be ensured.展开更多
文摘The investigation on the behavior of RE in microalloyed steel containing Nb and Ti indicates RE still have the effect of purifying molten steel and metamorphose inclusions even when the composition of S is pretty low(S<0 003%). The optimum performance of the experimental steels can be obtained when w RE / w O+S is controlled around 3 9. The content of solid solution RE can reach 1×10 -5 ～1×10 -4 order of magnitude in ultra low sulfur steel. The additions of RE can reduce the segregation of S and P at the grain boundary, delay the dynamic recrystallization, refine the grain and second phase particles, and promote the precipitation of (Nb, Ti)(C, N). RE also exhibit the microalloying effect in steel.
文摘Studies were made of the symmetric tensile-compressive low cycle fatigue behaviour and the influence of dynamic strain aging(DSA)pre-treatment of 18-8 austenitic stainless steel. Within the testing amplitude range of strain.±0.5 % to±1.5 %,the three processes of cyclic hardening,cyclic saturation and cyclic softening were observed.In the same amplitude of strain,the peak stress of the samples pre-treated by DSA is higher than that of solid-solu- tion and cold working pre-treatment,but no remarkable differences of the fatigue lives of them were found.TEM observation shows that the uniform and stable dislocation networks with high density form after DSA pre-treatment,which increases the cyclic peak stress.The cyclic softening results from the low dislocation density and elongated cell structure with low energy.
基金Project supported bythe Ministry of Science and Technology of China (2002BA315A-5)
文摘The influence of rare earth lanthanum and cerium on impact property of structural alloy steel with extra low sulfur and oxygen was studied by impact test and microanalysis. The results showed that rare earths increased impact power of the steel when their contents were about 0.005%. Proper addition of rare earths could purify grain boundaries and decrease amount of inclusions, and reduced the possibility of crack growth along grain boundaries and through inclusions. Therefore, such steel could absorb more crack growth energy while it was impacted. However, if the content of rare earths is excessive, the grain boundary would be weakened and brittle-hard phosphates and Fe-RE intermetallic would be formed, which worsened impact toughness of steel.
基金This research was supported by the State Key Fundamental Research Project (973 Project), (No. G199806150)
文摘The effect of [S] on strength and toughness of low alloy steel plates inwhich sum of [P], [N], T[O] is less than 8x10^(-5) and the effect of T[O] on strength and toughnessof the steel plates in which sum of [S], [P], [N] is less than 7x10^(-5) were investigated. It isfound that the strength of the steel plates decreases with increasing [S] content when [S] is lessthan 4x10^(-5). When [S] varies within the range of 4x10^(-5)-1.2x10^(-4), [S] has no significanteffect on strength of the steel. The strength of the steel plates increases with increasing T[O]content when T[O] is less than 30x10^(-6), but decreases with increasing T[O] when T[O] is more than3x10^(-5). The difference between the LETT in plate length direction and LETT in width directiondecreases with decreasing [S] content. However, even when [S] is decreased to 9x10^(-6), thedifference of the LETT is still 16℃. When T[O] varies between 1.8x10^(-5) and 5.2x10^(-5), the lowtemperature impact toughness of the steel plates slowly decreases with T[O] increasing. When T[O]increases to more than 5.2x10^(-5), the low temperature toughness of the steel rapidly decreaseswith increasing T[O] content.
文摘在宝钢炼钢厂300 t RH-KTB上进行了超低碳超低硫钢的预熔渣深脱硫试验。试验共12炉,预熔渣加入量为4 kg/t。试验结果表明,在RH平均初始w(S)为42.1×10-6条件下,处理终点平均w(S)达到30×10-6,最低w(S)达到22×10-6,最高脱硫率达到36.6%,平均脱硫率达到28.6%,取得了较好的深脱硫效果。采用预熔渣处理过程钢中w(TO)及w(N)均有所降低。试验炉次钢中最低w(TO)为12×10-6,平均w(TO)为13.3×10-6,最低w(N)为11×10-6,平均w(N)为13.8×10-6。RH终点钢中的夹杂物主要是Al2O3,95.1%的夹杂物小于5μm。
文摘In order to reduce the content of oxygen and sulfur in steel, and produce low-sulfur and low-oxygen steel, study on slag has been carried out. Refining slag system of CaO-SiO2-Al2O3 is put forward with the consideration of slag amount from converter, oxidizability of slag and activity of oxygen in molten steel. On this basis, refining slagging system for low-sulfur and low-oxygen steel has been developed combined with the modification of slag from converter and composition control of refining slag in LF treatment process. The results show that oxygen content is not more than 15×10-6, as well as sulfur content is as low as 0.005% in tube blank steel. And it achieves the production of low-sulfur and low-oxygen steel.
文摘Based on the fact of long period deep desulfurization treatment in LF,the relationships among top slag constituent in LF,molten steel constituent,stirring ability of blowing argon,molten steel temperature and desulphurization rate were analyzed.Through the experiments,the parameters about treatment technology of top slag in LF,the [Als] content in molten steel,slag charge match,molten steel temperature and the argon flow for stirring have been optimized.The desulphurization treatment period in LF can be shortened by 5～8 minutes.The target sulfur content in molten steel can be controlled below 30 ppm within one LF treatment period which is only 36 minutes.The LF treatment period of ultra-low sulfur steel can primarily match with the continuous casting period,multi-heat continuous casting can be ensured.
