铝合金辊底炉淬火工艺与7075板材淬火变形的规律研究

Research on the quenching process of aluminum alloy roller bottom furnace and the regularity of quenching deformation of 7075 plate

7075铝合金具备高比强度、热变形性、较优焊接性能和良好耐蚀性能等独特优势,在航空航天等领域被广泛应用。热处理工序的专用辊底炉是高端高精铝材生产的关键“卡脖子”短板装备和产能瓶颈装备,淬火板形的控制非常重要。为了对铝合金中厚板淬火过程的热应力与变形量进行预测和控制,本文利用数值模拟方法,研究连续辊式淬火过程不同喷水量与不同水量比对铝板温度场、应力场以及形变场的影响,用SolidWorks建立7075铝合金淬火过程的几何模型,用Fluent模拟铝板在不同喷水量和水量比的温度场,计算铝板淬火敏感区间的平均冷速,将铝板温度场导入ANSYS中计算应力场和形变场。结果表明,厚度为80 mm的7075铝合金厚板,在水量比为1∶1时中心面冷却不均匀,铝板尾部淬火敏感区间的冷速达10.35℃/s。淬火过程中铝板最大内应力值随时间的增加由头部向尾部后移并且数值递减;沿厚度的1/4和3/4处应力值最小;由于窄缝嘴射流冷却区冷却强度很大,水淬7 s时此区域应力值最大为132 MPa;水量比为1.2且喷水量较大时,整个冷却过程中总变形最小、内应力也最小。研究工作对现实生产工程中控制淬火板形提供了一定的参考意义。

7075 aluminum alloy has unique advantages such as high specific strength,excellent thermal deformation,superior welding performance and good corrosion resistance,which is widely used in aerospace and other fields.The dedicated roller bottom furnace for heat treatment process is a key bottleneck equipment and production capacity bottleneck equipment for high-end high-precision aluminum production,and the control of quenching plate shape is very important.In order to predict and control the thermal stress and deformation during the quenching process of aluminum alloy medium and thick plates,this paper uses numerical simulation methods to study the effects of different water spray rates and water flow ratios on the temperature,stress and deformation fields of aluminum plates during the continuous roller quenching process.SolidWorks software is used to establish a geometric model of the quenching process of 7075 aluminum alloy,and Fluent is used to simulate the temperature fields of aluminum plates under different water spray rates and water flow ratios.The average cooling rate of the sensitive zone of aluminum plate quenching is calculated,and the temperature field of aluminum plates is imported into ANSYS software to calculate the stress and deformation fields.The results showed that the 7075 aluminum alloy thick plate with a thickness of 80 mm had uneven cooling on the central surface at a water ratio of 1∶1,and the cooling rate in the quenching sensitive zone of the aluminum plate's tail end reached 10.35℃/s.The maximum stress value of aluminum plates during the quenching process shifts backwards from the head to the tail and decreases with time;The minimum stress value is at 1/4 and 3/4 of the thickness;Due to the high cooling intensity of the narrow slit nozzle jet cooling zone,the maximum stress value in this area is 132 MPa after 7 seconds of water quenching.During the entire cooling process,the minimum total deformation and minimum stress occur when the water ratio is 1.2 and the water spray amount is large.This study can ultimately provide reference for controlling the quenching plate shape in practical production engineering.