Abstract A medium-carbon steel AISI 1045 was hardened by a laser heat treatment (LHT), a multi-pin ultrasonic impact treatment (UIT), and two combined laser-ultrasonic surface treatments (UIT + LHT and LHT + UIT processes) to improve the wear resistance of the surface layer. The paper is focused on detecting the relationship between the surface roughness and microstructure, phase state, hardness, residual stress of the specimens hardened by the LHT, UIT and combined UI + LHT/LHT + UIT processes, and their wear and friction behaviors. The hardened plane specimens were examined after the short-term (15 min) and long-term (45 min) wear tests under oil-lubricated conditions in the quasi-static and dynamic loads. The analysis of the surface morphologies and cross-section profiles of the worn tracks were assessed by an optical 3D measurement system and scanning electron microscopy (SEM). The wear mechanisms are also discussed. Results showed that the combined LHT + UIT treatment provides a lower surface roughness (Ra ~0.25 μm) and a highest surface hardness (~11,000 HV0.05) while the combined UIT + LHT treatment leads to the deeper hardened zone by 1.5–2 times. As compared to the untreated specimen (dynamic tests), the wear loss magnitudes were respectively decreased by ~5%, 35%, 42%, and 84% after the UIT, LHT, combined UIT + LHT and LHT + UIT processes. The LHT + UIT-processed specimen has the highest wear resistance owing to the formation of the fine-grained martensitic microstructure, more flattened surface microrelief, and the absence of the oxide film.

中文翻译：

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结合激光相变硬化和超声波冲击应变硬化增强 AISI 1045 钢的耐磨性

摘要 一种中碳钢 AISI 1045 通过激光热处理 (LHT)、多针超声冲击处理 (UIT) 和两种激光-超声联合表面处理（UIT + LHT 和 LHT + UIT 工艺）硬化，以改善表层的耐磨性。重点检测了LHT、UIT和UI+LHT/LHT+UIT复合工艺淬火后试样的表面粗糙度与显微组织、相态、硬度、残余应力的关系及其磨损和摩擦行为。在准静态和动态载荷下在油润滑条件下进行短期（15 分钟）和长期（45 分钟）磨损试验后，对硬化平面试样进行了检查。通过光学 3D 测量系统和扫描电子显微镜 (SEM) 评估磨损轨迹的表面形态和横截面轮廓。还讨论了磨损机制。结果表明，联合 LHT + UIT 处理提供了较低的表面粗糙度 (Ra ~0.25 μm) 和最高的表面硬度 (~11,000 HV0.05) 而联合 UIT + LHT 处理导致更深的硬化区 1.5-2 倍. 与未处理的试样（动态测试）相比，在 UIT、LHT、组合 UIT + LHT 和 LHT + UIT 工艺后，磨损损失幅度分别降低了约 5%、35%、42% 和 84%。LHT + UIT 处理的试样由于形成细晶马氏体显微组织，更平坦的表面微浮雕，具有最高的耐磨性，