常规超声方法检测钢轨铝热焊焊缝时，不同区域焊缝的检测需更换不同K值的探头，检测速度慢且由于光斑和灰斑等缺陷反射很弱，很容易造成漏检。超声相控阵声束具有可偏转和聚焦的特点，使得声波反射能量足够大且不用频繁更换探头。通过对含已知机械加工缺陷和未知自然缺陷的钢轨铝热焊焊缝试样进行检测，验证了超声相控阵方法检测铝热焊焊缝的可行性和有效性。通过与常规超声检测方法进行对比，得出超声相控阵检测钢轨铝热焊焊缝具有速度快、效率高、重现性好和检测结果直观等优点。

While applying conventional ultrasound tests method to detect the rail joint of aluminum-thermic welding, for different detecting regions, it is needed to use different K property of probes, also, it is hard to detect the flaws of light spot and gray spot for the reason of signal reflecting, so utilizing focus and deflect of ultrasonic phased array to overcome conventional ultrasound tests method inadequacy. Through detecting rail joint of aluminum-thermic welding with nature and machining flaws, the effectiveness of ultrasonic phased array method was validated as compared with results of conventional ultrasound test. The experiment results showed the ultrasonic phased array inspection for rail joint of aluminum-thermic had fast detection speed and high efficiency; the result could be shown visually and reproducible.