一种高Al+Ti镍基高温合金在双相区和单相区的热塑性变形行为  

Hot Deformation Behavior of a Nickel-Base Superalloy with High Al and Ti Contents in Dual-Phase and Single-Phase Ranges

作　　者：赵广迪 武金江 Zhao Guangdi;Wu Jinjiang(University of Science and Technology Liaoning,Anshan 114051,China)

机构地区：[1]辽宁科技大学,辽宁鞍山114051

出　　处：《稀有金属材料与工程》2023年第2期630-638,共9页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51904146)。

摘　　要：高Al、Ti含量镍基变形高温合金开坯塑性的严重恶化已经成为制约其广泛应用的瓶颈。这类合金的热塑性特征受γ′析出相的显著影响,但以往关于γ′对其热变形行为影响的研究均未考虑晶界强化元素的干扰。本研究制备了一种不含C、B、Zr等晶界强化元素的高Al+Ti镍基变形高温合金铸锭并对其进行了充分的均匀化处理,重点研究了该合金在1060℃(γ/γ′双相区)和1170℃(γ单相区)的塑性变形行为。结果表明,γ单相区的变形抗力远小于γ/γ′双相区,且γ单相区的热塑性明显更好。有趣的是在γ单相区的流变曲线上出现了明显的屈服降现象,而在γ/γ′双相区并未出现。这可能由于在γ单相区有更多Al、Ti被释放,这些以溶质形式存在的Al、Ti能有效阻碍位错移动并最终将其锁定。在γ/γ′双相区和γ单相区开裂的模式均为沿晶开裂,说明在热加工过程中这类合金的晶界是最薄弱环节。当对数应变达到0.36时在γ/γ′双相区和γ单相区均已发生不连续动态再结晶(DDRX),且随着应变的增大DRX晶粒数量明显增多,但晶粒尺寸无明显变化。由于一次γ′对晶界具有钉扎作用,γ单相区的DRX晶粒尺寸明显大于γ/γ′双相区,但前者DRX晶粒的颗粒密度明显更小。总之,γ单相区变形抗力明显更低且热塑性更好的主要原因是,其DRX晶粒的快速长大会迅速降低原始晶界附近的位错密度。The severe deterioration of thermal plasticity for nickel-base wrought superalloys with high Al and Ti contents during cogging has become the bottleneck for their wide application, and their thermal plasticity can be significantly affected by the γ′ precipitation.However, previous studies about the role of γ′ in hot deformation behaviors of such alloys did not consider the interference of grain boundary strengthening elements. In this research, a high Al+Ti nickel-base superalloy ingot without adding grain boundary strengthening elements C, B and Zr was prepared and fully homogenized. Afterwards, the hot deformation behaviors of this as-homogenized ingot at 1060 ℃(γ/γ′ dual-phase range) and 1170 ℃(γ single-phase range) were investigated. The results show that, the deformation resistance in γ single-phase range is much lower than that in γ/γ′ dual-phase range, and the plasticity of γ single-phase range is much better. Interestingly,in γ single-phase range a typical yield drop phenomenon appears, while no such phenomenon appears in γ/γ′ dual-phase range. This may be because the release of more Al and Ti solutes in γ single-phase range hinders the movement of dynamic dislocations and finally locks them.Both the γ single-phase and γ/γ′ dual-phase ranges show intergranular cracking, which indicates that initial grain boundaries are the weakest link in hot working process of such alloys. When the logarithmic strain reaches 0.36, discontinuous dynamic recrystallization(DDRX) has occurred in both the γ single-phase and γ/γ′ dual-phase ranges, and with the increase of strain the number of DRX grains increases significantly, but the DRX grain size has no obvious change. Owing to the pinning effect of γ′ to grain boundaries, the DRX grain size in γ single-phase range is much greater than that in the γ/γ′ dual phase range, but the number density of DRX grains in the γsingle-phase range is much smaller. The main reason for the lower deformation resistance and better thermal plasti

关 键 词：镍基高温合金 热塑性变形 动态再结晶 γ′相 

分 类 号：TG146.15[一般工业技术—材料科学与工程]