微量Zr/B/Ti对C71500合金铸态组织和力学性能的影响

Effects of Trace Zr,B,Ti on Microstructure and Mechanical Properties of AS Cast C71500 Alloys

通过硬度测试、金相和电镜观察、能谱分析以及差热分析等方法研究微量元素Zr,Ti和B对C71500合金铸态组织和性能的影响。结果表明,微量Zr,Ti和B对合金有明显的晶粒细化和性能强化作用。微量的B即可强烈地细化合金的铸造组织,Zr虽然也在一定程度上具有细化作用,但效果没有B明显。Ti和B的复合添加并没有在B的基础上进一步细化晶粒,但显著地提高合金的硬度。随着晶粒细化程度的提高,枝晶偏析逐渐减弱,铸锭的三晶区消除,断面呈现全部等轴晶。

The effects of microalloying elements Zr,Ti and B on the microstructure and mechanical properties of as cast C71500 alloys are investigated by hardness test,Optical Microscopy,Scanning Electron Microscopy,Energy Dispersive Spectrum and Differential Scanning Calorimetry.The comparative investigations indicate that the grain size is reduced by addition of the trace alloying elements and the hardness property is increased obviously.The solidification microstructure is markedly refined by race boron addition and the grain size is also decreased by Zirconium addition although not so obvious.Moreover,there is little further drop of grain size when B is added together with Ti compared to addition of boron alone,yet hardness property get visible improvement further.As the reduction of grain size constitutional segregation decrease and the microstructure morphology throughout the castings is changed from a coarse grained dendritic structure to a fine grained equiaxed structure accompanied by the elimination of tri-crystal region structure.