引擎應用之滾針軸承，常需要採用表面處理。目前最多採用電鍍銅、鍍銀的處理方式。在電鍍過程中，使用酸清洗脫脂，與電鍍製程都會有氫析出滲透至基材，而導致氫脆的現象。一般鋼材中，氫的擴散是一種可逆反應，可使用加熱烘烤使氫擴散出基材。去氫烘烤效果，可用測氫設備來驗證，其中OE-GDS可分析出氫含量比例與基材中深度位置等關係。 保持器用材料SCM-415，在熱處理採用滲碳氮化法，電鍍後其拉伸強度與韌性皆有明顯損失，其缺口拉伸強度損失率甚至可達48%，去氫烘烤後拉伸強度雖可回復，但材料延性會有所損失。 比對測氫結果發現，烘烤時間越久，去氫效果越佳，氫殘留含量與其延性成相對比例關係。而去氫烘烤對於減低氫脆的效果，在於氫於基材內部會平均分佈，其次才是減少氫含量。表面滲碳氮化層為強氫補集位置，會影響氫擴散能力與速度，所以容易於表面形成富氫層，而在斷口金相中也發現表面滲碳層為氫源而影響破裂型態與裂痕成長模式，而沿晶破裂、脆性穿晶破裂與氫致韌斷等破裂機構形成不同斷面金相特徵。 Hydrogen embrittlement is a serious problem of metal after plating process in engineering. The cage of needle roller bearing, it applies to high speed and high performance engine, usually has silver or copper plating to reduce the friction and heating. The “baking” process is working to rid metal of hydrogen. We can use the “hydrogen determination” and “OE-GDS” to study the baking effect of hydrogen consistency in SCM-415. We find short time baking process only cause the hydrogen re-distribution in this metal and the hydrogen trap will effect the result. From result of tensile and SSRT notch tensile test, we find the HE will cause reducing ductility of material. Including Intergranular, dimple and quasi-cleavage will appear in the fractography of test, and depend on hydrogen concentration position. Most failure modes of HE are the intergrainular fracture.
