T-TRIP: Investigation of transformation induced plasticity during precipitation formation in quenched and tempered steels and maraging steels

T-TRIP：调质钢和马氏体时效钢沉淀形成过程中相变诱发塑性的研究

• 批准号: 428958028
• 负责人: Professor Dr.-Ing. Volker Schulze
• 金额: --
• 依托单位: Institut für Angewandte Materialien - Werkstoffkunde (IAM-WK)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/428958028?language=en
• 关键词: TRIP; Investigation; transformation; induced; plasticity

The T-TRIP project aims to investigate more closely the so far not systematically studied transformation induced plasticity (TRIP) during the precipitation formation in steels under mechanical stresses. For this purpose, a selection of steels from the class of martensitic aging (maraging) steels and tempering steels are investigated as example materials. The choice of these steel classes results from important technological applications. Heat-treated steels are usually tempered after hardening, resulting in carbide formation. Since residual stresses due to manufacturing are commonly present in steel components, the precipitation reaction occurs under the influence of an internal load. This applies in particular to modern surface hardening methods by means of electro-magnetic induction or lasers. Martensitic aging steels are used, for example, in welding processes or in additive manufacturing. These processes result in extremely high cooling rates and associated thermally induced residual stresses. Due to the layer wise processing, re-heating of already solidified areas occurs and a precipitation formation under the influence of stresses and increased temperatures is initiated. From both classes steel compositions which differ in the volume content of the precipitates will be selected for this investigation. The experiments include dilatometry for the measurement of the TRIP effect at various applied tensile and compressive stresses as well as isothermal and continuous temperature control. In addition, the influence of the applied stress on the resulting mechanical properties of the material is to be investigated. As indicators for this, the yield strength and the hardness after the heat treatment are to be determined. In the next step, the transferability between the steel classes will be examined in order to determine the influence of the precipitation type (carbides in tempered steels as well as intermetallic phases in martensitic aging steels) on the transformation induced plasticity. The properties of the matrix as well as the morphologies of the precipitates will be characterized by means of X-ray and electron microscopic methods.The findings of the mechanical experiments are then to be interpreted and evaluated with the help of the results from the microscopic characterization in order to give a more detailed insight into the mechanisms during martensitic aging and tempering. The determined dependencies of the measured transformation induced plasticity will be described by means of suitable models for both steel classes. In particular, the dependence on the precipitated volume content for the respective steels should be correlated with the transformation plasticity constant characteristic of the TRIP effect. Finally, from the results and created models the transfer to the technological application in the field of heat treatment and component distortion can be made possible.

T-TRIP 项目旨在更仔细地研究迄今为止尚未系统研究的钢在机械应力下析出形成过程中的相变诱发塑性 (TRIP)。为此，我们研究了马氏体时效（马氏体时效）钢和回火钢中的一些钢作为示例材料。这些钢种的选择源于重要的技术应用。热处理钢通常在硬化后进行回火，从而形成碳化物。由于制造产生的残余应力通常存在于钢部件中，因此在内部载荷的影响下会发生析出反应。这尤其适用于通过电磁感应或激光的现代表面硬化方法。马氏体时效钢用于焊接工艺或增材制造等领域。这些过程导致极高的冷却速率和相关的热致残余应力。由于逐层加工，已固化区域会重新加热，并在应力和温度升高的影响下开始形成沉淀。从这两个类别中，将选择析出物体积含量不同的钢成分用于本次研究。实验包括膨胀测量法，用于测量各种施加的拉应力和压应力下的 ​​TRIP 效应以及等温和连续温度控制。此外，还需要研究施加的应力对材料机械性能的影响。作为其指标，测定热处理后的屈服强度和硬度。下一步，将检查钢种之间的可转移性，以确定沉淀类型（回火钢中的碳化物以及马氏体时效钢中的金属间相）对相变诱导塑性的影响。基体的性质以及沉淀物的形态将通过 X 射线和电子显微镜方法进行表征。然后借助微观表征结果来解释和评估机械实验的结果为了更详细地了解马氏体时效和回火过程中的机制。将通过两个钢种的合适模型来描述所测量的相变诱发塑性的确定的依赖性。特别地，对各种钢的析出体积含量的依赖性应与TRIP效应的相变塑性常数特征相关。最后，根据结果和创建的模型，可以将其转移到热处理和部件变形领域的技术应用。