螢光磁粉探傷廣泛應用於鐵磁性材料表面和近表面微小缺陷的檢測。自動化的缺陷識別系統很大程度的提高了檢測效率，在對探測結果進行圖像處理時，工件表面產生的背景和缺陷磁痕的對比度直接影響磁粉探傷的可靠性。本文從表面 粗糙度的基本參數出發，對其引起工件表面背景磁痕堆積的機理進行了模擬研究。進一步的，研究了表面粗糙度大小與螢光磁粉探傷系統缺陷識別極限的關係。

Magnetic particle inspection (MPI) technique is widely applied to locate fine defects on the surface and sub-surface of ferromagnetic parts. Automated defect recognition system has improved inspection efficiency significantly compared with manual inspection. However the test piece background during fluorescent MPI and its contrast with crack indication have a significant influence on the reliability of inspection results for picture processing by automated defect recognition system. This paper addresses the fundamental principles of magnetic particle accumulation on test piece surfaces by simulation on the basis of surface roughness parameters. Furthermore, a study has been performed regarding the relationship between surface roughness (Ra) and detecting limit for a fluorescent magnetic particle inspection (MPI) system.