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Effects of preheating and cooling on the crack defects of laser solid formed Rene 104 superalloy parts
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ( IF 2.6 ) Pub Date : 2020-03-10 , DOI: 10.1177/0954405420909182
Weisheng Ying 1 , Fuzhu Han 1 , Junhua Wang 1
Affiliation  

In this study, laser solid forming technology has been used to fabricate Rene 104 nickel-based superalloy parts, and severe crack problems were found during the laser solid forming process. To solve the crack problems, the effects of preheating and cooling on the microstructure and crack defects of the laser solid forming Rene 104 superalloy were experimentally investigated. The experimental results demonstrated that crack intensity in parts obtained using laser solid forming decreased with the increase in the preheating temperature. However, when the cooling process was not controlled, the parts obtained using laser solid forming would still exhibit severe crack problems even if the preheating temperature was increased to 750 °C. Therefore, instead of natural cooling, a slow cooling strategy was used after the laser solid forming process in the experiments. It was proved that decreasing the cooling rate of the substrate also helped in eliminating the cracks. Using the slow cooling strategy, crack-free Rene 104 superalloy parts could be fabricated at a relatively low preheating temperature. Moreover, it was found that the multiple growth direction of columnar dendrites under high preheating temperature restricted the propagation of cracks. The microsegregation of Al and Ti in the interdendritic regions decreased when the slow cooling strategy was used, leading to improvements in ductility. Aside from the evolution of the microstructure, the relief of thermal stress during the slow cooling process was another important reason for eliminating the cracks.

中文翻译:

预热和冷却对激光固体成形 Rene 104 高温合金零件裂纹缺陷的影响

本研究采用激光固体成形技术制造了Rene 104镍基高温合金零件,在激光固体成形过程中发现了严重的裂纹问题。为解决裂纹问题,实验研究了预热和冷却对激光固体成形Rene 104高温合金组织和裂纹缺陷的影响。实验结果表明,随着预热温度的升高,激光固体成形零件的裂纹强度降低。然而,当冷却过程没有得到控制时,即使预热温度提高到750°C,使用激光固体成形获得的零件仍然会出现严重的裂纹问题。因此,不是自然冷却,实验中在激光固体成形过程之后使用了缓慢冷却策略。事实证明,降低基材的冷却速度也有助于消除裂纹。使用缓慢冷却策略,可以在相对较低的预热温度下制造无裂纹的 Rene 104 高温合金部件。此外,还发现在高预热温度下柱状枝晶的多重生长方向限制了裂纹的扩展。当采用缓冷策略时,Al 和 Ti 在枝晶间区域的微观偏析减少,导致延展性提高。除了微观结构的演变外,缓冷过程中热应力的释放是消除裂纹的另一个重要原因。事实证明,降低基材的冷却速度也有助于消除裂纹。使用缓慢冷却策略,可以在相对较低的预热温度下制造无裂纹的 Rene 104 高温合金部件。此外,还发现在高预热温度下柱状枝晶的多重生长方向限制了裂纹的扩展。当采用缓冷策略时,Al 和 Ti 在枝晶间区域的显微偏析减少,导致延展性提高。除了微观结构的演变外,缓冷过程中热应力的释放是消除裂纹的另一个重要原因。事实证明,降低基材的冷却速度也有助于消除裂纹。使用缓慢冷却策略,可以在相对较低的预热温度下制造无裂纹的 Rene 104 高温合金部件。此外,还发现在高预热温度下柱状枝晶的多重生长方向限制了裂纹的扩展。当采用缓冷策略时,Al 和 Ti 在枝晶间区域的微观偏析减少,导致延展性提高。除了微观结构的演变外,缓冷过程中热应力的释放是消除裂纹的另一个重要原因。可以在相对较低的预热温度下制造无裂纹的 Rene 104 高温合金部件。此外,还发现在高预热温度下柱状枝晶的多重生长方向限制了裂纹的扩展。当采用缓冷策略时,Al 和 Ti 在枝晶间区域的微观偏析减少,导致延展性提高。除了微观结构的演变外,缓冷过程中热应力的释放是消除裂纹的另一个重要原因。可以在相对较低的预热温度下制造无裂纹的 Rene 104 高温合金部件。此外,还发现在高预热温度下柱状枝晶的多重生长方向限制了裂纹的扩展。当采用缓冷策略时,Al 和 Ti 在枝晶间区域的微观偏析减少,导致延展性提高。除了微观结构的演变外,缓冷过程中热应力的释放是消除裂纹的另一个重要原因。当采用缓冷策略时,Al 和 Ti 在枝晶间区域的微观偏析减少,导致延展性提高。除了微观结构的演变外,缓冷过程中热应力的释放是消除裂纹的另一个重要原因。当采用缓冷策略时,Al 和 Ti 在枝晶间区域的微观偏析减少,导致延展性提高。除了微观结构的演变外,缓冷过程中热应力的释放是消除裂纹的另一个重要原因。
更新日期:2020-03-10
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