The aim of this work is to generate an advantageous compressive residual stress distribution in the surface area of hot-formed components by intelligent process control with tailored cooling. Adapted cooling is achieved by partial or temporal instationary exposure of the specimens to a water–air spray. In this way, macroscopic effects such as local plastification caused by inhomogeneous strains due to thermal and transformation-induced loads can be controlled in order to finally customise the surface-near residual stress distribution. Applications for hot-formed components often require special microstructural properties, which guarantee a certain hardness or ductility. For this reason, the scientific challenge of this work is to generate different residual stress distributions on components surfaces, while the geometric as well as microstructural properties of AISI 52100 alloy stay the same. The changes in the residual stresses should therefore not result from the mentioned changed component properties, but solely from the targeted process control. Within the scope of preliminary experimental studies, tensile residual stresses in a martensitic microstructure were determined on reference components, which had undergone a simple cooling in water (from the forming heat), or low compressive stresses in pearlitic microstructures were determined after simple cooling in atmospheric air. Numerical studies are used to design two tailored cooling strategies capable of generating compressive stresses in the same components. The developed processes with tailored cooling are experimentally realised, and their properties are compared to those of components manufactured involving simple cooling. Based on the numerical and experimental analyses, this work demonstrates that it is possible to influence and even invert the sign of the residual stresses within a component by controlling the macroscopic effects mentioned above.

这项工作的目的是通过具有定制冷却功能的智能过程控制，在热成型部件的表面区域中产生有利的压缩残余应力分布。适应性冷却是通过将样品部分或暂时地静置在水-空气喷雾中来实现的。以此方式，可以控制宏观效应，例如由于热和相变引起的载荷而由不均匀应变引起的局部塑化，以便最终定制表面附近的残余应力分布。热成型部件的应用通常需要特殊的微观结构特性，以保证一定的硬度或延展性。因此，这项工作的科学挑战是要在组件表面产生不同的残余应力分布，AISI 52100合金的几何和微观结构特性保持不变。因此，残余应力的变化不应该由提到的已更改的组件属性引起，而应仅由目标过程控制引起。在初步实验研究的范围内，确定马氏体微观结构中的拉伸残余应力是在参考部件上确定的，这些参考部件已经在水中进行了简单的冷却（通过成形热），或者在大气中进行了简单的冷却之后就确定了珠光体组织中的低压缩应力。空气。数值研究用于设计两种量身定制的冷却策略，这些策略能够在相同的组件中产生压缩应力。通过量身定制的冷却工艺已通过实验得以实现，并将其性能与涉及简单冷却的制造部件的性能进行比较。根据数值和实验分析，这项工作表明可以通过控制上述宏观效应来影响甚至反转组件内残余应力的符号。