Effect of Ce-Mg-Si （light RE） and Y-Mg-Si （heavy RE） nodulizers on the microstructures and mechanical properties of heavy section ductile iron was investigated to develop the material of spent-nuclear-fuel contain...Effect of Ce-Mg-Si （light RE） and Y-Mg-Si （heavy RE） nodulizers on the microstructures and mechanical properties of heavy section ductile iron was investigated to develop the material of spent-nuclear-fuel containers. Two as-casts were treated by the same quality percentage of light RE and heavy RE, respectively. Four positions were chosen to stand for different solidification cool-ing rates of specimens. The tensile strength, elongation and impact toughness of specimens treated by heavy RE were all higher than those of the specimens treated by light RE. With the decrease of cooling rate, the mechanical properties of two specimens decreased, and the fracture morphology changed from ductile fracture to brittle fracture. The improving effect of mechanical properties between heavy RE and light RE was obvious due to the better anti-degradation property of heavy RE. While the solidification process lasted for more than 250 min, the improving effect was not obvious due to serious spheroidalization decaying.展开更多
To improve the mechanical properties of heavy section ductile cast iron, bismuth(Bi) was introduced into the iron. Five castings with different Bi content from 0 to 0.014 wt.% were prepared; and four positions in the ...To improve the mechanical properties of heavy section ductile cast iron, bismuth(Bi) was introduced into the iron. Five castings with different Bi content from 0 to 0.014 wt.% were prepared; and four positions in the casting from the edge to the center, with different solidifi cation cooling rates, were chosen for microstructure observation and mechanical properties test. The effect of the Bi content on the graphite morphology and mechanical properties of heavy section ductile cast iron were investigated. Results show that the tensile strength, elongation and impact toughness at different positions in the fi ve castings decrease with a decrease in cooling rate. With an increase in Bi content, the graphite morphology and the mechanical properties at the same position are improved, and the improvement of mechanical properties is obvious when the Bi content is no higher than 0.011wt.%. But when the Bi content is further increased to 0.014wt.%, the improvement of mechanical properties is not obvious due to the increase of chunky graphite number and the aggregation of chunky graphite. With an increase in Bi content, the tensile fracture mechanism is changed from brittle to mixture ductile-brittle fracture.展开更多
基金supported by National Natural Science Foundation of China(51174068,51374086)
文摘Effect of Ce-Mg-Si （light RE） and Y-Mg-Si （heavy RE） nodulizers on the microstructures and mechanical properties of heavy section ductile iron was investigated to develop the material of spent-nuclear-fuel containers. Two as-casts were treated by the same quality percentage of light RE and heavy RE, respectively. Four positions were chosen to stand for different solidification cool-ing rates of specimens. The tensile strength, elongation and impact toughness of specimens treated by heavy RE were all higher than those of the specimens treated by light RE. With the decrease of cooling rate, the mechanical properties of two specimens decreased, and the fracture morphology changed from ductile fracture to brittle fracture. The improving effect of mechanical properties between heavy RE and light RE was obvious due to the better anti-degradation property of heavy RE. While the solidification process lasted for more than 250 min, the improving effect was not obvious due to serious spheroidalization decaying.
基金supported by the National Natural Science Foundation of China(Nos.51174068 and 51374086)
文摘To improve the mechanical properties of heavy section ductile cast iron, bismuth(Bi) was introduced into the iron. Five castings with different Bi content from 0 to 0.014 wt.% were prepared; and four positions in the casting from the edge to the center, with different solidifi cation cooling rates, were chosen for microstructure observation and mechanical properties test. The effect of the Bi content on the graphite morphology and mechanical properties of heavy section ductile cast iron were investigated. Results show that the tensile strength, elongation and impact toughness at different positions in the fi ve castings decrease with a decrease in cooling rate. With an increase in Bi content, the graphite morphology and the mechanical properties at the same position are improved, and the improvement of mechanical properties is obvious when the Bi content is no higher than 0.011wt.%. But when the Bi content is further increased to 0.014wt.%, the improvement of mechanical properties is not obvious due to the increase of chunky graphite number and the aggregation of chunky graphite. With an increase in Bi content, the tensile fracture mechanism is changed from brittle to mixture ductile-brittle fracture.
