The mechanical properties after tempering and intercritical annealing of medium manganese steels with 4 wt% Mn for forging applications are presented. After forging with subsequent air cooling, heat treatments were performed, specifically tempering from 250 and 450 °C and intercritical annealing between 600 and 675 °C. Tensile properties, Charpy V-notch impact toughness, and hardness were determined and compared with microstructural features characterized by metallography and synchrotron measurements, leading to the classification of six different heat treatment stages for medium manganese steels. Furthermore, the effects of different alloying additions (boron 0.0016–0.0057 wt%, molybdenum 0.2 wt%, and aluminum 0.5 wt%) are discussed with respect to the mechanical properties. It is shown that boron increases the impact toughness more effectively in the tempering regime, while the molybdenum alloyed samples exhibit higher toughness after intercritical annealing. Most of the materials and heat treatment states follow the inverse relationship between toughness and strength, while the aluminum alloyed samples show a superior toughness after tempering.

中文翻译：

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空气硬化 4 wt% 中锰钢的回火和临界间退火

介绍了用于锻造应用的含 4 wt% Mn 的中锰钢在回火和临界间退火后的机械性能。锻造和随后的空气冷却后，进行热处理，特别是从 250 到 450 °C 的回火和在 600 到 675 °C 之间的临界间退火。确定拉伸性能、夏比 V 型缺口冲击韧性和硬度，并将其与通过金相和同步加速器测量表征的微观结构特征进行比较，从而对中锰钢进行六种不同热处理阶段的分类。此外，还讨论了不同合金添加量（硼 0.0016–0.0057 wt%、钼 0.2 wt% 和铝 0.5 wt%）对机械性能的影响。结果表明，硼在回火状态下更有效地提高了冲击韧性，而钼合金样品在临界间退火后表现出更高的韧性。大多数材料和热处理状态遵循韧性和强度的反比关系，而铝合金样品在回火后表现出优异的韧性。