Cr含量对核用近α钛合金组织与性能的影响

Effect of Cr Content on the Microstructure and Mechanical Properties of Near-α Titanium Alloy for Pressure Vessel of Nuclear Reactor

以核用新型Ti-Al-V-Zr系近α钛合金为研究对象,在基础合金上添加0.76%(质量分数,下同)与1.52%的Cr元素,研究了Cr含量对近α钛合金组织及性能的影响规律。结果表明:Cr促进了组织中次生α的析出,Cr的添加导致了针状组织中V的富集;XRD结果显示:合金中的β相含量随Cr含量增加而增加;Cr元素的加入,在不降低合金塑性的条件下,可以显著提高合金的室温抗拉强度和屈服强度,这与合金的组织状态有关。示波冲击试验发现:Cr含量在0.76%左右时,合金的冲击韧性值最大,屈强比最高。断口结果表明:Cr含量在0.76%的T2合金比其他合金断口处颈缩明显,韧窝深,且撕裂棱较小,断裂路径曲折,这与合金的组织中次生α相的数量与形状有关。

The effects of Cr content on the microstructures, phases, tensile properties and impact properties of the Ti-Al-V-Zr alloys with addition of 0.76%~1.52% Cr were investigated for nucleus applications. Microstructural analyses were carried out using scanning microscopy, X-ray diffraction and quantitative microprobe analysis. The addition of Cr refines the microstructure of the modified alloys, and promotes the formation of the acicular α grains. XRD results show that the total amount of β phase increases with the increase of Cr content. The addition of Cr improves the strength significantly but not improves the plasticity of the modified alloys. T2 alloy has much higher value of the impact toughness and energy among all the studied alloys. The experimental results indicate that the fracture in Ti-Al-V-Zr alloys is influenced by Cr addition considering the influence of the number and the shape of the second α phase. They have the great potential to become new candidates for nucleus applications.