We have developed a multi-stage variable speed (MSV) isothermal forming process based on strain rate sensitivity (SRS) analysis, and successfully produced a large size of rib-web component of magnesium alloy from a cylindrical billet. The obtained rib-web component has been processed into parts for mechanical properties examination and the examination results met the standard of being safely used in aircrafts. The process parameters of the forming technology and microstructure change were explicitly linked by the SRS coefficient. The finite element (FE) simulation and SRS distribution were implemented to identify the relationship among process parameters, shaping characteristics, and microstructure development. The MSV speed process was employed for reducing the forming load, refining grain sizes and increasing the strength of the component. With the selected process parameters the maximum forming load was reduced to be less than 20 MN, which is 55.3% lower than that used in the same process with the initial constant speed unchanged. Fine dynamic recrystallization (DRX) were observed from all parts of the forged cover plate including the convex, ribs, and web region. It was also found that higher strain resulted in more uniform distribution of fine β-Mg₁₇Al₁₂ precipitates and larger DRX volume fraction. Importantly the developed isothermal forming process with severe plastic deformation can be applied for obtaining grain refinement so improving the mechanical properties of Mg products.

我们已经基于应变率敏感性（SRS）分析开发了多级变速（MSV）等温成型工艺，并成功地从圆柱坯生产了大尺寸的镁合金肋腹板组件。所获得的肋腹板组件已被加工成用于机械性能检查的零件，并且检查结果符合在飞机上安全使用的标准。SRS系数明确链接了成形技术和微观结构变化的工艺参数。进行了有限元（FE）模拟和SRS分布，以识别工艺参数，成形特性和微结构发展之间的关系。采用MSV速度工艺来减少成形负荷，细化晶粒尺寸并提高组件的强度。使用选定的工艺参数，最大成型载荷减少到小于20 MN，这比相同工艺中初始恒定速度不变的情况下降低了55.3％。从锻造盖板的所有部分（包括凸部，肋部和腹板区域）都观察到了精细的动态重结晶（DRX）。还发现较高的应变导致细β-Mg的分布更均匀₁₇ Al ₁₂沉淀，DRX体积分数更大。重要的是，可以将已开发的具有严重塑性变形的等温成型工艺用于获得晶粒细化，从而改善镁产品的机械性能。