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电子束增材制造 K438 研究进展

Research progress of K438 by electron beam additive manufacturing

  • 摘要: K438镍基高温合金具有优异的耐热腐蚀性能和高温抗氧化性能,被广泛应用于低于900 ℃工况的航空发动机涡轮叶片等热端部件。区别于传统制备工艺,增材制造 (Additive Manufacturing, AM) 技术因其生产流程短、组织成分均匀以及部件高温力学性能良好等优点,成为“不可焊性”K438高温合金的理想工艺。AM中,激光源增材制造 (Laser Source Additive Manufacturing, LSAM) 容易产生热应力聚集,因而具有较高的开裂敏感性;电子束选区熔化 (Selective Electron Beam Melting, SEBM) 技术基于真空环境条件和粉末床预热程序,可以精确控制温度变化,显著降低制件内部的残余热应力,从而减少裂纹数量。本文针对SEBM制备K438高温合金的研究现状进行了综述,总结了工艺成形过程中工作环境、工艺参数和后处理对K438高温合金质量的影响,以及K438高温合金在不同工艺状态下的相组织演变。

     

    Abstract: K438, Nickel-based superalloy, has excellent heat-corrosion resistance and high-temperature oxidation resistance, and is widely used in hot components of aero-engines such as turbine blades under working conditions of 900 ℃. Different from traditional preparation process, Additive Manufacturing (AM) technology has become an ideal process for "non-weldable" K438 superalloy due to its advantages of short production process, homogeneous microstructure and good high-temperature mechanical properties of components. Laser Source Additive Manufacturing (LSAM) in AM technology is prone to thermal stress accumulation and thus has a high susceptibility to cracking. Selective Electron Beam Melting (SEBM) technology is based on vacuum environmental conditions and powder bed preheating procedures, which can precisely control temperature changes and significantly reduce the residual thermal stress inside the workpiece, thereby reducing the number of cracks. In this paper, the current research status of K438 superalloy prepared by SEBM is reviewed, including the influence of working environment, process parameters and post-treatment technology on the quality of K438 superalloy, and the microstructure evolution trend of K438 superalloy under different process conditions, as well as the evolution of the phase organization of K438 superalloy under different process conditions.

     

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