Abstract This study encompasses a comprehensive account of the abrasive wear properties of carbide-free, ultrahigh-strength bainitic steels processed through ausforming at three different temperatures well below the recrystallization stop temperature followed by bainitic transformation at temperatures close to the Ms temperature. Five medium-carbon, high-silicon compositions were designed for the study by suitably varying the alloying levels of carbon, vanadium, niobium, molybdenum, and aluminum. While ausforming at lower temperatures enabled a large number of nucleation sites leading to significant refinement of bainitic laths, the decomposition of austenite at relatively low transformation temperatures was accelerated due to the presence of a high dislocation density, thus enabling completion of bainitic transformation in a reasonable length of time. The steels were characterized in respect of microstructural features and mechanical properties, besides evaluation of wear resistance through a high-stress abrasive wear testing method with natural granite abrasives. The microstructures comprised different fractions of bainitic ferrite and/or granular bainite (56–68%), martensite (0–25%), besides a significant fraction of retained austenite (20–34%) manifesting as pools and also interlath films, depending on the ausforming conditions and subsequent cooling paths. A tensile strength of 1900 MPa level was achieved with hardness exceeding 500 HV for the medium-temperature ausformed steel containing a high carbon content that also showed lowest mass loss in the wear test. The hardness-to-mass loss ratio appeared highly promising with some of the carbide-free bainitic steels on par with or better than the reference martensitic steel. The high work-hardening capability as a consequence of the strain-induced austenite to martensite transformation was considered as the main factor for the superior abrasive wear resistance of the carbide-free bainitic steels.

中文翻译：

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高应力磨粒磨损条件下无碳化物中碳贝氏体钢的特性

摘要 本研究全面介绍了在远低于再结晶停止温度的三种不同温度下通过奥氏成形加工的无碳化物、超高强度贝氏体钢的磨料磨损性能，然后在接近 Ms 温度的温度下进行贝氏体转变。通过适当改变碳、钒、铌、钼和铝的合金含量，设计了五种中碳、高硅成分用于研究。虽然在较低温度下的奥氏体成形能够产生大量的成核位点，从而导致贝氏体板条的显着细化，但由于存在高位错密度，奥氏体在相对较低的转变温度下分解加速，从而能够在合理的时间内完成贝氏体转变。除了通过使用天然花岗岩磨料的高应力磨料磨损测试方法评估耐磨性外，还对钢的微观结构特征和机械性能进行了表征。显微组织包括不同比例的贝氏体铁素体和/或粒状贝氏体 (56-68%)、马氏体 (0-25%)，除了显着比例的残余奥氏体 (20-34%) 表现为熔池和板间膜，具体取决于在 ausforming 条件和随后的冷却路径。对于含有高碳含量的中温 ausformed 钢，其抗拉强度达到 1900 MPa 水平，硬度超过 500 HV，在磨损试验中也显示出最低的质量损失。一些无碳化物贝氏体钢的硬度与质量损失比与参考马氏体钢相当或更好。由于应变引起的奥氏体向马氏体转变而产生的高加工硬化能力被认为是无碳化物贝氏体钢具有优异耐磨性的主要因素。