Hsieh Ping-Yu, Wu Bo-Ding, Hung Fei-Yi
Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan.
Materials (Basel). 2024 Nov 28;17(23):5851. doi: 10.3390/ma17235851.
This study selected 17-4PH (Type 630) precipitation-hardening stainless steel as the raw material. After subjecting the material to precipitation hardening and softening heat treatments, the effects of these treatments on the microstructural characteristics and mechanical properties were investigated, along with a thermal fatigue test. The results showed that after the precipitation hardening heat treatment, the ultimate tensile strength and hardness of 17-4PH stainless steel increased. However, the ductility was around 2%, indicating a severe brittleness effect, which is unfavorable for ordnance applications. A double aging treatment for 12 h resulted in a combination of softness and ductility, with an ultimate tensile strength of 900 MPa, ductility of 26%, and hardness HRC 28. These material properties are suitable for cold forging in ordnance and other applications. In addition, a thermal fatigue test was conducted on the softened 17-4PH material from 750 °C to room temperature. After 3000 thermal cycles, there was no significant change in material properties, ensuring it can withstand 3000 rounds of gunfire in a barrel with excellent durability. Furthermore, XRD and fracture surface analysis confirmed that the softening mechanism of 17-4PH stainless steel and its high-temperature phase stability could provide a reference for cold forging and high-temperature applications.
本研究选用17-4PH（630型）沉淀硬化不锈钢作为原材料。对该材料进行沉淀硬化和软化热处理后，研究了这些处理对微观结构特征和力学性能的影响，并进行了热疲劳试验。结果表明，沉淀硬化热处理后，17-4PH不锈钢的抗拉强度和硬度增加。然而，伸长率约为2%，表明存在严重的脆化效应，这对于军械应用是不利的。12小时的双重时效处理导致了柔软性和延展性的结合，抗拉强度为900MPa，伸长率为26%，硬度为HRC 28。这些材料性能适用于军械及其他应用中的冷锻。此外，对软化后的17-4PH材料在750℃至室温下进行了热疲劳试验。经过3000次热循环后，材料性能没有显著变化，确保其在枪管中能够承受3000发子弹射击，具有出色的耐久性。此外，XRD和断口分析证实，17-4PH不锈钢的软化机制及其高温相稳定性可为冷锻和高温应用提供参考。
