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利用X射线衍射仪(XRD)、金相显微镜(OM)、维氏硬度计和万能电子拉伸试验机,研究了N i47Ti44Nb9形状记忆合金冷轧板材中的B2相沿轧向(RD)和横向(TD)的织构,以及热处理对冷轧板材硬度、显微组织、拉伸性能和恢复应变的影响。结果表明:冷轧板材的织构主要由较强的{111}丝(即γ-丝)和较弱的{332}丝组成。沿轧向,强组分向γ-丝中的{111}<110>靠近,而沿横向,强组分靠近γ-丝中的{111}<112>;随淬火温度提高,冷轧板材的硬度缓慢下降,超过500℃后,硬度急剧下降,到700℃以后硬度基本不变;冷轧板材在550℃发生明显再结晶,700℃处理后再结晶晶粒发生长大;随淬火温度提高,沿轧向(RD)和横向(TD)的应力诱发马氏体相变临界应力(σM)和可恢复应变(εr)降低。低于550℃淬火板材,沿轧向的临界应力σM高于沿横向方向的,而沿横向的可恢复应变εr较高,高于550℃淬火,沿横向的临界应力σM提高,可恢复应变εr沿轧向和横向的数值接近。
The effects of B2 phase along rolling direction (RD) and transverse direction (Ra) on N i47Ti44Nb9 shape memory alloy cold rolled sheet were investigated by X-ray diffraction (XRD), optical microscope (OM), Vickers hardness tester and universal tensile tester. TD) texture, as well as heat treatment on the cold rolled sheet hardness, microstructure, tensile properties and recovery strain. The results show that the texture of cold-rolled sheet mainly consists of stronger {111} filaments (ie, γ-filaments) and weaker {332} filaments. Along the rolling direction, the strong component is close to the {111} <110> in the γ-filament while the strong component is close to {111} <112> in the γ-filament along the transverse direction. As the quenching temperature increases, The hardness decreased slowly, and the hardness dropped sharply after 700 ℃. The hardness remained unchanged after 700 ℃. The cold-rolled sheet recrystallized obviously at 550 ℃ and the recrystallized grains grew up after treated at 700 ℃. With the increase of quenching temperature, Stress induced martensitic transformation critical stress (σM) and recoverable strain (εr) reduction along the rolling direction (RD) and transverse direction (TD). Below 550 ℃, the critical stress σM along the rolling direction is higher than along the transverse direction, while the recoverable strain εr along the transverse direction is higher. When the temperature is above 550 ℃, the critical stress σM increases and the recoverable strain εr Close to the value along the rolling and horizontal.