Study On Producing Boron-iron Composite Material By Suspend Casting

The developing of nuclear-industry takes a chance for searching high-boron steel. As a shielding material, the high-boron steel combines the boron and iron's anti-radiant excellence and it also have superiority in price. The high-boron steel as a prospective shielding material has already gained enough attention and deeply research. The routine high-boron steel series shielding materials join boron into carbon-steel. In common carbon-steel, a lot of boron will promote to separate out eutectic structure in casting Fe-B-C alloy. The metallurgical structures of Fe-B-C casting alloy are matrix and eutectic structure. The boride distributing in the casting Fe-B-C alloy likes a net and it will increase the alloy's brittleness and reduce alloy's toughness. High temperature normalizing treatment could not change the boride's figure and location.At present, the research about high-boron steel aim at controlling the content of boron and taking alloying measure. But all the ways can regulate and boost the capability of high-boron steel at a low percent of boron. The content of boron is too low to apply it to nuclear industry. In addition, alloying, such as join Ti element into carbon-steel is expensive and it can't apply abroad.This experiment program to produce boron-iron composite material by a new technology which be called suspend casting to overcome the limitation of common technology to manufacture high-boron steel. The suspend casting is propitious to thin crystal grain and organization. Join suspending agent into metal can enhance the intensity and plasticity during or after the crystallization time. The suspend casting can also reduce the segregation of casting and increase the density of casting. By the way, it can enhance the uniformity of the material. Because of all the excellence spoke above, the suspend casting can boost casting's high-temperature mechanical capability. Meanwhile, the material designer can design the character of composition material through controlling the amount of suspending agent. Take use of the character of suspend casting to overcome the limitation of orthodox technology producing high-boron steel. Through adding a lot of boride grain to steel, lots of boride grains don't melt and disperse in the casting. It changes the crystal concreting mode and transforms the concreting organization. So, it can avoid occurring lots of high-boron phase eutectic structure and enhance the intensity and toughness of material.The outcome of the test shows that: taking use of suspend casting technology to manufacture the high-boron phase/iron composition material is a available measure to solve the contradiction between increasing boron content and material's mechanical capability.If fill some precondition such as choosing appropriate base metal and suspending agent, taking suspending agent covering technology, it can reduce the amount of melting suspending agent. B₄C nickel plating can efficiently separate B₄C and Fe, and relax the reaction between B₄C and Fe. It can also reduce the Fe₂B phase separating out from the base metal. All the Fe₂B phases distribute in the base metal as lots of independent islands and don't connect to net each other. So the material's toughness increases. Otherwise, the diameter of suspending agent works on the material's capability and affects boron element's distributing.While the diameter of Fe-B grain suspending agent is during 0.1mm to 0.4mm, with the diameter increasing, the toughness of composition material increases. Meanwhile, the boron element distributes more uniformly. But the B₄C grain's diameter doesn't show the similar relationship with the material's impact toughness. The other way round, with the diameter of B₄C grain increasing, the tensile strength of composition material increases. In the test, although heat treatment can't change the high-boron phase's distributing, it can evidently enhance base metal's capability and improve the mechanical capability of composition material.