7B50铝合金超厚板淬火残余应力的中子衍射研究

The ultra-thickness plate of 7B50 aluminum alloy with high strengh and toughness, good corrosion resistance and welding performance will be used for the beam and frame of large domestic airplane as the load bearing components. The quenching process that results in high strengh also leaves high residual stress. Effected by the quenching residual stress, the ultra-thickness plate of 7B50 aluminum alloy receives gross deformation after machining and then cann’t be assembled with other components. So analysis and control of the quenching residual stress becomes one of the key technologies in production of ultra-thickness plate of 7B50 aluminum alloy. Spray quenching is an advanced process, which could adjust the cooling velocity to obtain the samples with supersaturation and low residual stress. Among the methods of residual stress measurement, neutron diffraction can provide nondestructively 3D-mapping of residual stress in engineering component, and therefore becomes the most effective technique in characterizing quenching residual stress of ultra-thickness plate of 7B50 aluminum alloy. In this subject, in combination of finite element simulation, neutron diffraction will be used as the key technique to study the three dimensional distribution of residual stress induced by spray quenching and optimize the process of spray quenching. This study will provide experimental and theoretical instruction for application of the ultra-thickness plate of 7B50 aluminum alloy in beam and flame component of large domestic airplane.

7B50铝合金由于具有高的强度和韧性、良好的焊接和耐腐蚀性能，其超厚板将用于国产大飞机的横梁和框架承力结构部件。7B50铝合金的高强度通过淬火工艺获得，同时引入高的残余应力。受淬火残余应力的影响，7B50铝合金超厚板遇到了加工严重变形的问题，将导致无法装机使用。淬火残余应力的分析和控制成为7B50铝合金超厚板制备的关键技术之一。喷淋淬火是一种先进的淬火工艺，通过调整不同阶段的冷却速度可获得过饱和状态且低残余应力的样品。在诸多应力测量方法中，中子衍射技术能够无损测量工程部件的三维残余应力分布，成为表征7B50铝合金超厚板淬火残余应力最有效的方法。因此，以中子衍射为核心手段，结合有限元模拟方法，探索喷淋淬火残余应力的三维分布，优化喷淋淬火工艺，为7B50铝合金超厚板应用于国产大飞机的框梁结构件提供实验和理论指导。

7B50铝合金由于具有高的强度和韧性、良好的焊接和耐腐蚀性能，其超厚板将用于国 产大飞机的横梁和框架承力结构部件。研究和控制淬火残余应力是 7B50 铝合金超厚板具有低残余应力、耐腐蚀性能的关键，通过调整不同阶段的冷却速度可获得过饱和状态且低残余应力的样品。. 本申请利用多级淬火工艺制备了7B50 铝合金淬火样品，利用中子衍射技术和有限元模拟技术获得了淬火残余应力的分布，两种方法取得了较好的一致性。实验与模拟结果表明，多级淬火工艺能够有效的降低淬火残余应力，同时不会造成额外的力学性能损失。