【摘要】：鎂合金作為21世紀最輕的金屬材料受到日益廣泛的重視,其低密度、高比強度及易于回收等優(yōu)點使鎂合金在越來越多的領(lǐng)域得到廣泛應(yīng)用。而ZK60鎂合更是一種典型的高強鎂合金,但其在鑄造過程中容易產(chǎn)生晶間化合物MgZn相,導(dǎo)致熱軋過程中熱裂傾向及加工硬化嚴重,軋制性能差。本文以自制ZK60鎂合金為研究對象,通過均勻化-熱軋-冷軋-退火的變形工藝,從變形機理和織構(gòu)變化角度研究軋制溫度、道次變形量、軋制方式及退火處理對金相組織、織構(gòu)及力學性能的影響,具體結(jié)論如下:(1)軋制溫度升高,會促使合金中非基面滑移系啟動,導(dǎo)致動態(tài)再結(jié)晶程度增加,晶粒細化。400℃軋制時平均晶粒尺寸最小為9.35μm,同時(0002)基面織構(gòu)最弱。(2)增加道次壓下量會提高組織中位錯密度,促進動態(tài)再結(jié)晶程度增加,從而降低平均晶粒尺寸,同時(0002)基面織構(gòu)強度增加。但變形量太大會降低組織均勻性,從而影響力學性能。(3)交叉軋制會促進二次孿晶生成,同時非基面滑移系的啟動促使晶間變形加劇,導(dǎo)致動態(tài)再結(jié)晶程度增加,細化晶粒。晶粒細化有利于晶粒旋轉(zhuǎn)和晶界移動,改變軋制方向會迫使原先向軋制方向旋轉(zhuǎn)的晶粒向TD方向偏移,最終導(dǎo)致(0002)基面織構(gòu)強度由8.61降到7.12,,織構(gòu)類型由(0001)[0(?)10](0°,120°)轉(zhuǎn)變?yōu)?0001)[(?)(?)30](0°,139.11°)和((?)105)[2(?)11](20.16°,18.02°,60°)。晶粒細化和織構(gòu)弱化導(dǎo)致合金塑性提高,各向異性降低。(4)退火溫度升高,會加快靜態(tài)再結(jié)晶完成時間,提高合金的力學性能,但退火溫度過高會導(dǎo)致晶粒粗化,降低強度和塑性。延長退火時間,合金的強度和塑性會先增加后下降。同時合理的退火工藝會降低織構(gòu)強度。本文最終的退火工藝選擇為340℃×1h。(5)通過顯微硬度測試法表征合金退火時的靜態(tài)再結(jié)晶過程,得出靜態(tài)再結(jié)晶完成時間,從而計算出20%冷軋量的ZK60鎂合金激活能Q為58.8KJ/mol,并得出該合金在不同退火溫度下的靜態(tài)再結(jié)晶分數(shù)與保溫時間關(guān)系的方程。
[Abstract]:Magnesium alloys, as the lightest metal materials in the 21st century, have been paid more and more attention. Their advantages of low density, high specific strength and easy to be recovered have made magnesium alloys widely used in more and more fields. ZK60 magnesium bonding is a typical high strength magnesium alloy, but it is easy to produce intergranular compound MgZn phase in the casting process, which leads to the hot cracking tendency and work hardening in hot rolling process, and the rolling performance is poor. In this paper, the microstructure of ZK60 magnesium alloy was studied by homogenization, hot rolling, cold rolling and annealing, from the point of view of deformation mechanism and texture change, rolling temperature, pass deformation, rolling mode and annealing treatment. The effects of texture and mechanical properties are as follows: (1) the increase of rolling temperature will lead to the initiation of non-base slip system of the alloy and increase the degree of dynamic recrystallization. The average grain size is 9.35 渭 m and (0002) texture is the weakest. (2) increasing pass reduction will increase dislocation density and increase dynamic recrystallization. Thus the average grain size is reduced and the (0002) basal texture strength is increased. However, the amount of deformation can reduce the homogeneity of microstructure and affect the mechanical properties. (3) Cross rolling will promote the formation of secondary twins, and the starting of non-basal slip system will aggravate the deformation between grains and increase the degree of dynamic recrystallization. Refine the grain. Grain refinement is beneficial to grain rotation and grain boundary movement. Changing rolling direction will force the original rolling direction to shift to TD direction, resulting in the (0002) base texture strength decreasing from 8.61 to 7.12%. The texture types changed from (0001) [0 (?) 10] (0 擄, 120 擄) to (0001) [(?) 30] (0 擄, 139.11 擄) and (?) 105) [2 (?) 11] (20.16 擄, 18.02 擄, 60 擄). Grain refinement and texture weakening increase the plasticity and decrease the anisotropy of the alloy. (4) annealing temperature increases the completion time of static recrystallization and improves the mechanical properties of the alloy, but too high annealing temperature will lead to grain coarsening. Reduce strength and plasticity. When annealing time is prolonged, the strength and plasticity of the alloy will increase first and then decrease. At the same time, reasonable annealing process will reduce the texture strength. In this paper, the final annealing process is 340 鈩，

本文編號：2402008