EB炉熔炼TC4钛合金热轧板材的组织性能研究

Microstructure and Properties of TC4 Titanium Alloy Hot-rolled Sheet by Electron Beam Cold Bed Furnace Melting

摘要:

以工业化电子束冷床炉（EB炉）熔炼的TC4钛合金扁锭为研究对象，对其进行热轧变形，研究单向和换向热轧工艺对TC4钛合金板材显微组织与力学性能的影响。结果表明：TC4钛合金扁锭显微组织为魏氏组织，经过热轧塑性变形后，晶界已充分破碎，α相集束发生扭折、变形和破碎，且纵横交错分布，呈网篮状。随着热轧换向次数的增加，片状α相纵横交错越明显，降低了其在轧向和横向的各向异性，换向二次热轧的板材综合性能最优。TC4钛合金的断裂转变形式为单向热轧RD方向的韧性断裂、TD方向的韧性+准解理混合型断裂→换向一次热轧RD方向的韧+脆混合型断裂、TD方向的韧性+准解理混合型断裂→换向两次热轧的韧性断裂。热轧板材主要是α-Ti和β-Ti的基体相。单向热轧板材的晶粒在<0001>方向存在择优取向；换向一次热轧板材的晶粒取向主要介于<0001>和<"1" ?2"1" ?0>晶向之间；换向二次热轧板材晶粒取向向<01"1" ?0>方向移动，其晶粒取向介于<0001>和<01"1" ?0>方向之间。

Abstract:

The effects of unidirectional and reversal hot rolling on the microstructure and mechanical properties of TC4 titanium alloy ingot melted by electron beam cold bed furnace were studied. The results show that the microstructure of TC4 titanium alloy slab is Widmannstatten structure. After hot rolling plastic deformation, the grain boundary is fully broken, and the α phase bundle is twisted, deformed and broken, and it is criss-crossed and distributed in a basket shape. With the increase of the number of reversing hot rolling, the lath-like α phase cross-section is more obvious, which reduces the anisotropy in the rolling direction and the transverse direction, and the comprehensive performance of the reversing secondary hot-rolled sheet is optimal. The fracture transformation forms of TC4 titanium alloy are unidirectional hot-rolled RD ductile fracture, TD ductile + quasi-cleavage mixed fracture reversed one-time hot-rolled RD ductile + brittle mixed fracture, TD ductile + quasi-cleavage mixed fracture reversed two-time hot-rolled ductile fracture. The hot-rolled sheet is mainly a matrix phase of α-Ti and β-Ti. The grain orientation of the unidirectional hot-rolled sheet has a preferred orientation in the <0001> direction; the grain orientation of the reversing once hot-rolled sheet is mainly between <0001> and<"1" ?21 ?0>crystal orientation; the grain orientation of the sheet moves toward <01"1" ?0>, and its grain orientation is between <0001> and <01"1" ?0>. Key words: Electron beam cold bed furnace; TC4 titanium alloy; reversing hot rolling; microstructure; mechanical properties