δ相对GH4169合金强韧性的影响规律研究

Influence of δ Phase on strength and toughness of GH4169 Alloy

摘要:

通过断裂韧度J0.2BL以及冲击韧性测试研究了δ相百分含量对GH4169合金韧性的影响。结果表明,随固溶温度增加,δ相含量从1.54%降低到0.045%,晶粒尺寸从12.59 μm长大到35.21 μm,δ相含量对拉伸强度无显著影响,但断裂韧度J0.2BL从112 KJ/m增加到355 KJ/m, 冲击韧性从35 J增加到75 J。δ相的析出会导致其周边出现无γ″相析出区,当大量δ相沿晶界分布时,则沿晶界形成无强化相析出带,在应力作用下,δ相与无强化相析出区基体的应变差会导致界面开裂、形成孔洞。在无强化相析出区孔洞快速连接形成裂纹,裂纹沿晶扩展与空洞汇合,降低了裂纹扩展阻力,加速了裂纹的扩展。因此δ相的存在为裂纹提供了扩展通道,降低了材料的塑韧性。

关键词:GH4169合金;δ相;强韧性;裂纹扩展

Abstract:

The influence of the δ phase on the toughness of GH4169 alloy was investigated by means of the fracture toughness J0.2BLand instrumented impact experiment. Experimental results indicate that with the increase of solution temperature, δ phase content reduced from 1.54% to 0.045%, and grain size grew up from 12.59 to 35.21 μm. δ phase content has no obvious effect on the strength of the material, but the fracture toughnessJ0.2BL increased from 112 KJ/m to 355 KJ/m, the impact toughness increased from 35 J to 75 J. δ phase is mainly distributed along the grain boundary, there is no strengthening phase precipitation around it. The zone with no strengthening phase near the grain boundary will be formed, it promote the crack propagation along the grain boundary. Moreover, the δ phase itself is the intermetallic compound. Under certain plastic deformation conditions, it is easy to separate from micro plastic zone and form a cavity. In the micro plastic zone, the cavities are rapidly interlinked to form a crack, and the crack grows along the grain boundary with the cavity, which reduces the crack propagation resistance and accelerates the crack propagation. Therefore, the presence of δ phase provides an extended channel for the crack and reduces the toughness of the material.

Key words:GH4169 alloy; δ phase; strength and toughness; crack propagation