leometwu的部落格

照片有點失焦. out of focus.

滲碳後只有左右兩側未經再加工, 保留了滲碳時產生的晶界氧化. 此面刀痕輕磨後拋光, 可輕易看出晶界氧化現象. (見下面第3張照片以後)

較黑處是刀痕低凹處. Darker area is the bottom of the turning marks. IGO presented as darker lines along grain boundaries.

晶粒內都是麻田散鉄. 晶界氧化處, 合金被氧吃掉了. 硬化能較低, 淬不出麻田散鉄. 只得到 Fine Pearlite (dark area) along grain boundaries severely reduce bonding strength between grains of tempered Martensites(light area).

只做金相檢驗. 沒做破損分析. 確切起裂處是1還是2 ? 不得而知. Fatigue crack origin: 1, or 2 ? is not known because only the microstructure inspection is requested.