不鏽鋼及其他的鐵系金屬被歸類為不可鑽石車削加工，因為在鑽石與鐵金屬之間所產生的熱化學反應將造成不可接受的磨耗。近年來已有研究將不鏽鋼試片在低溫的狀態（<450℃）用離子氮化來增加沃斯田鐵基材中的鐵原子與氮原子形成γ-Fe4N的硬層。本研究鑽石車削的實驗在下列加工參數中完成：單點鑽石刀具、最大切削速度180m/min、最大切深至5μm以及使用少量的無機油當作切削液。結果顯示在相同的參數下車削不鏽鋼時會獲得快速的刀具磨耗和不好的表面粗糙度，而車削經過離子氮化的試片會得到3nm以下的表面粗糙度且刀腹磨耗小於0.5μm。可發現經由表面處理之鋼材所造成之刀具磨耗比無表面處理時改善許多。 本研究將不同鉻含量鋼材，STAVAX不鏽鋼、H13工具鋼與SKD61工具鋼，三種材料在電漿離子滲氮表面處理後，經由單點鑽石車削加工，在不同鉻含量鋼材中刀具磨耗會隨鉻含量減少而有明顯降低情形。 Stainless steel and other ferrous metals are normally classified as not diamond turnable for the unacceptable tool wear caused by the thermal-chemical reaction between diamond and ferrous metals. In the present research, stainless steel specimens were plasma nitrided at a relatively low temperature (<450oC) to prevent the depletion of Cr content at the austenite matrix and to give a hardened layer where Fe atoms are bonded to nitrogen atom to form γ’-Fe4N. Diamond turning experiments were subsequently carried out under the following machining conditions: single crystal diamond tool, cutting speed up to 180 m/min, cut depth up to 5um and light mineral oil as the cutting fluid. The results showed that, given the same machining conditions while rapid tool wear and poor surface finish were obtained when diamond turning the untreated stainless steel, surfaces with Ra around 8nm and flank wear up to 5um were observed on turning the plasma treated surface where too much CrxN instead of FexN were formed on the surface. Surfaces with Ra better than 3 nm and very low tool wear (<0.5um flank wear) were achieved on turning the plasma nitrided stainless steel. This means that the surface treatment has profound effects on the tool wear and it is possible to reduce tool wear and improve surface finish by carefully modifying the microstructure of the surface.