The low-energy, multi-impact fracture resistance and the abrasiveness of the cross-rolled low alloy white cast iron grinding balls were studied after heat treatments at residual rolling temperature. Moreover, the mean...The low-energy, multi-impact fracture resistance and the abrasiveness of the cross-rolled low alloy white cast iron grinding balls were studied after heat treatments at residual rolling temperature. Moreover, the means by which they are damaged and characters of the wear surface were analyzed. The results show that high resistance to impact fracture and high abrasiveness can be achieved after appropriate heat treatment at residual rolling temperature. This kind of heat treatment technology has several advantages under low impact and hard abrasive. These results are very useful for determining the optimized heat treatment technology at residual rolling temperatures.展开更多
The effect of manganese on the as-cast structure and hardening behavior of high chromium white cast iron subjected to sub-critical treatment was studied.The results indicate that the fraction of retained austenite and...The effect of manganese on the as-cast structure and hardening behavior of high chromium white cast iron subjected to sub-critical treatment was studied.The results indicate that the fraction of retained austenite and the manganese distribution in as-cast alloys are controlled by manganese content.The manganese distribution in as-cast alloys is not homogeneous.The manganese content in carbide is higher than that in matrix.Whether the secondary hardening occurs or not and the peak hardness of secondary hardening is controlled by manganese content in retained austenite in as-cast structure.Higher manganese content can cause more retained austenite.The secondary hardening occurs in sub-critical treating process if the fraction of retained austenite is high.展开更多
The effect of cooling rate on structure and properties of wear-resistant low chromium cast iron after 40% hot deformation was investigated by metallographic and scanning electron microscope. The results show that the ...The effect of cooling rate on structure and properties of wear-resistant low chromium cast iron after 40% hot deformation was investigated by metallographic and scanning electron microscope. The results show that the cooling rate is closely related to the structure and properties, and for the cast iron, the best comprehensive mechanical properties were obtained by forced air cooling with a cooling rate as about 7 ℃/s. The reason and regularity for the change of mechanical properties were analyzed.展开更多
The influence of heating temperature on mechanical properties of low chromium wear resistant cast iron containing rare earth elements was studied by means of metallographic examination, scanning electron microscopic e...The influence of heating temperature on mechanical properties of low chromium wear resistant cast iron containing rare earth elements was studied by means of metallographic examination, scanning electron microscopic examination and mechanical property test. The experimental results show that heating temperature has great effect on impact toughness (α_k), bending fatigue (σ_(bb)) and relative toughness (σ_(bb)×f), but little effect on hardness (HRC). When the specimen was held at 960 ℃ for 3 h, it has better comprehensive mechanical properties, and the reason and regularity of the change for mechanical properties of the cast iron were reviewed.展开更多
The effect of rare earth elements on dynamics of thermal fatigue crack′s propagation in low alloy white cast iron was studied. The results show that the generation and growth of the thermal fatigue crack can be restr...The effect of rare earth elements on dynamics of thermal fatigue crack′s propagation in low alloy white cast iron was studied. The results show that the generation and growth of the thermal fatigue crack can be restrained and the activation energy for the crack′s propagation can be increased by adding a certain amount of RE, and especially, the restraint for the thermal fatigue crack′s propagation is more evident under the combined action of RE and heat treatment at high working temperatures, which can be attributed to the segregation of RE to interfaces, the participation of granular carbides and the change of eutectic carbide morphology.展开更多
The valence electron structure of alloying austenite of 3C-15Cr high chromium white cast iron with different Mn contents from 1% to 6% is analyzed by BLD method and EET. Results show that the addition of Mn has major ...The valence electron structure of alloying austenite of 3C-15Cr high chromium white cast iron with different Mn contents from 1% to 6% is analyzed by BLD method and EET. Results show that the addition of Mn has major influence on the valence electron structure of the alloying austenite, especially on that of Fe-C, Fe-C-Cr and Fe-C-Cr-Mn unit cells of it. The effect becomes weak when Mn content is over 4%. Based on the effect of nA, FcD, the weighting of each unit cell and the degree of undercooling on phase transition of the austenite, we can calculate the retained austenite content of as-cast structure of the high chromium white cast iron. The calculation results coincide well with those of the experiment. The phase transition characters of the austenite in high chromium white cast iron can be forecasted through valence electron structure analysis of alloying austenite by BLD method and EET on the basis of Fe-C-Cr equilibrium phase diagram.展开更多
The effect of austempering temperature on the microstructure and properties of a high chromium white cast iron was investigated with the Rietveld refinement method. The result shows that the upper bainite exists in th...The effect of austempering temperature on the microstructure and properties of a high chromium white cast iron was investigated with the Rietveld refinement method. The result shows that the upper bainite exists in the sampie austempered at 623 K and the martensite, lower bainite, M7C3, and retained austenite exist in the samples austempered at 563 K and 593 K. The relative content of the retained austenite increases with increasing the austemper- ing temperature from 563 K to 623 K. The higher hardness, impact toughness and impact abrasive wear resistance can be obtained for the specimen austempered at 593 K.展开更多
基金Item Sponsored by Guiding Program of Science and Technology Research of Jilin Province of China (20000513)
文摘The low-energy, multi-impact fracture resistance and the abrasiveness of the cross-rolled low alloy white cast iron grinding balls were studied after heat treatments at residual rolling temperature. Moreover, the means by which they are damaged and characters of the wear surface were analyzed. The results show that high resistance to impact fracture and high abrasiveness can be achieved after appropriate heat treatment at residual rolling temperature. This kind of heat treatment technology has several advantages under low impact and hard abrasive. These results are very useful for determining the optimized heat treatment technology at residual rolling temperatures.
文摘The effect of manganese on the as-cast structure and hardening behavior of high chromium white cast iron subjected to sub-critical treatment was studied.The results indicate that the fraction of retained austenite and the manganese distribution in as-cast alloys are controlled by manganese content.The manganese distribution in as-cast alloys is not homogeneous.The manganese content in carbide is higher than that in matrix.Whether the secondary hardening occurs or not and the peak hardness of secondary hardening is controlled by manganese content in retained austenite in as-cast structure.Higher manganese content can cause more retained austenite.The secondary hardening occurs in sub-critical treating process if the fraction of retained austenite is high.
文摘The effect of cooling rate on structure and properties of wear-resistant low chromium cast iron after 40% hot deformation was investigated by metallographic and scanning electron microscope. The results show that the cooling rate is closely related to the structure and properties, and for the cast iron, the best comprehensive mechanical properties were obtained by forced air cooling with a cooling rate as about 7 ℃/s. The reason and regularity for the change of mechanical properties were analyzed.
文摘The influence of heating temperature on mechanical properties of low chromium wear resistant cast iron containing rare earth elements was studied by means of metallographic examination, scanning electron microscopic examination and mechanical property test. The experimental results show that heating temperature has great effect on impact toughness (α_k), bending fatigue (σ_(bb)) and relative toughness (σ_(bb)×f), but little effect on hardness (HRC). When the specimen was held at 960 ℃ for 3 h, it has better comprehensive mechanical properties, and the reason and regularity of the change for mechanical properties of the cast iron were reviewed.
文摘The effect of rare earth elements on dynamics of thermal fatigue crack′s propagation in low alloy white cast iron was studied. The results show that the generation and growth of the thermal fatigue crack can be restrained and the activation energy for the crack′s propagation can be increased by adding a certain amount of RE, and especially, the restraint for the thermal fatigue crack′s propagation is more evident under the combined action of RE and heat treatment at high working temperatures, which can be attributed to the segregation of RE to interfaces, the participation of granular carbides and the change of eutectic carbide morphology.
文摘The valence electron structure of alloying austenite of 3C-15Cr high chromium white cast iron with different Mn contents from 1% to 6% is analyzed by BLD method and EET. Results show that the addition of Mn has major influence on the valence electron structure of the alloying austenite, especially on that of Fe-C, Fe-C-Cr and Fe-C-Cr-Mn unit cells of it. The effect becomes weak when Mn content is over 4%. Based on the effect of nA, FcD, the weighting of each unit cell and the degree of undercooling on phase transition of the austenite, we can calculate the retained austenite content of as-cast structure of the high chromium white cast iron. The calculation results coincide well with those of the experiment. The phase transition characters of the austenite in high chromium white cast iron can be forecasted through valence electron structure analysis of alloying austenite by BLD method and EET on the basis of Fe-C-Cr equilibrium phase diagram.
基金Item Sponsored by Key Project on Natural Science for the Education Department of Anhui Province (2006KJ080A)
文摘The effect of austempering temperature on the microstructure and properties of a high chromium white cast iron was investigated with the Rietveld refinement method. The result shows that the upper bainite exists in the sampie austempered at 623 K and the martensite, lower bainite, M7C3, and retained austenite exist in the samples austempered at 563 K and 593 K. The relative content of the retained austenite increases with increasing the austemper- ing temperature from 563 K to 623 K. The higher hardness, impact toughness and impact abrasive wear resistance can be obtained for the specimen austempered at 593 K.
