Li Ji, Wo Yujie, Wang Zhigang, Ren Wenhao, Zhang Wei, Zhang Jie, Zhou Yang
School of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
Hubei Key Laboratory of High-Quality Special Steel, Daye Special Steel Co., Ltd., Huangshi 435001, China.
Materials (Basel). 2024 Jun 5;17(11):2754. doi: 10.3390/ma17112754.
With the development of the petroleum industry, the demand for materials for oilfield equipment is becoming increasingly stringent. The strength increase brought about by time strengthening is limited in meeting the needs of equipment development. The GH3625 alloy with different strength levels can be obtained through cold deformation and heat treatment processes. A study should be carried out to further develop the potential mechanical properties of GH3625. In this study, the GH3625 alloy was cold drawn with different reductions in area (0-30%) and heat treated, and its mechanical properties were tested. The microstructure of the alloy during deformation and heat treatment was characterized by methods such as optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) based on the principles of physical metallurgy. The strength increase caused by dislocation strengthening was calculated from the dislocation density, tested by X-ray diffraction (XRD). The calculated value was compared to the measured value, elucidating the strengthening effect of cold deformation and heat treatment. The results showed that the yield strength and yield ratio of the cold-drawn alloy significantly reduced after aging at 650 °C and 760 °C. Heat treatment can make a cold-deformed material recover, ablate dislocations, and greatly reduce the dislocation density in the microstructure of the GH3625 alloy, which was the main factor in the decrease in yield strength. The work-hardening gradient of the cold-drawn material varied greatly with different reductions in area. When the reduction in area was small (10%), the hardness gradient was obvious. When it increased to 30%, the alloy was uniformly strengthened as the deformation was transmitted to the axis. This study can provide more mechanical performance options for GH3625 alloy structural components in the petrochemical industry.
随着石油工业的发展，对油田设备材料的需求日益严格。时效强化所带来的强度提升在满足设备发展需求方面存在局限。通过冷变形和热处理工艺可获得不同强度水平的GH3625合金。应开展研究以进一步开发GH3625的潜在力学性能。在本研究中，对GH3625合金进行不同面积缩减率（0 - 30%）的冷拔并进行热处理，测试其力学性能。基于物理冶金原理，采用光学显微镜（OM）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）等方法对合金在变形和热处理过程中的微观结构进行表征。由位错密度计算位错强化引起的强度增加，并通过X射线衍射（XRD）进行测试。将计算值与测量值进行比较，阐明冷变形和热处理的强化效果。结果表明，冷拔合金在650℃和760℃时效后屈服强度和屈强比显著降低。热处理可使冷变形材料恢复、消除位错，并大幅降低GH3625合金微观结构中的位错密度，这是屈服强度降低的主要因素。冷拔材料的加工硬化梯度随面积缩减率的不同变化很大。当面积缩减率较小时（10%），硬度梯度明显。当增加到30%时，随着变形传递至轴线，合金得到均匀强化。本研究可为石化行业中GH3625合金结构部件提供更多力学性能选择。
