熱處理環節對鋼鐵材料之機械性質影響甚大，而手工具用鋼料之熱處理，旨在使手工具產品之硬度、扭力值達到一定標準，並使其擁有良好的耐磨耗性與細緻的金相組織。本文使用兩種含碳量0.66%的鉻鉬鋼，代號CM1及CM2，此兩種材料有別於目前市售螺絲起子用具所使用的SAE6150、SAE8660、AISI-S2鋼料，未有使用至手工具產品生產上，對其最直接的熱處理為調質熱處理，而由於其含碳量在0.66%，因而沃斯回火熱處理亦可做為其熱處理製程的選項，因而對CM1及CM2施與兩種不同的熱處理，比較其兩者經不同處理後的差異，並應用於十字頭端(Phillips Bits)之內置螺絲起子頭，產品的技術指標以芯部硬度58-62HRC、破壞扭力值達到220 kg-cm，疲勞壽命20000次為目標。
最終得到，CM1於沃斯回火，以200℃，30分鐘之鹽浴，較CM1使用調質製程時的機械性質較為好；而CM2使用沃斯回火與使用調質後之機械性質相差無幾，因而使用淬火860℃，持溫30分鐘，回火225℃，60分鐘為最佳參數，可得到最大扭力值。CM1工件經沃斯回火處理後，芯部硬度達到60.1HRC，扭力值227.8 kg-cm；CM2工件經調質處理後芯部硬度達到59.5HRC，扭力值219.9 kg-cm。CM1與CM2工件經沃斯回火處理後表面有脫碳現象，兩者之壽命並未達20000次循環之標準，後續應與表面處理議題相結合，應可改善疲勞壽命之問題。

The heat treatment process is crucial to the mechanical properties of steel materials. The purpose of heat treatment for hand tool steels is to gain fine microstructure and great abradability. The two Cr-Mo steel materials used in this study named CM1 and CM2 respectively, differs from commercially available materials such as SAE6150, SAE8660 and AISI-S2. The most direct heat treatment process for these two steels is quench and temper (QT). Because the carbon content of these two steels is 0.66%, Austempering is also a considerable heat treatment option to do.
We exerted QT and Austempering on the screwdriver bits in the shape specification of length 25 mm, 1/4 in. hex., Ph.2 tip made of CM1 and CM2. After these two heat treatment process, we will compare the mechanical properties of the treated specimens. The technical indicators are the hardness of the treated specimen between HRC58-62, the torque value reaches 220kg-cm, and the fatigue life must reaches 20,000 cycles.
Finally, we known that CM1 product after Austempering in 200℃ salt bath held for 30 minutes will get better mechanical properties than the QT one. The mechanical properties of CM2 products after Austempering in 200℃salt bath held for 30 minutes are closed to the QT one.
The CM1 product after the Austempering process with austenizing 880℃ holding for 30minutes and 200℃salt soaking for 30 minutes will get 60.1 HRC center hardness, 227.8kg-cm fracture torque value. The CM2 product after the QT process with austenizing 860℃ holding for 30minutes and temper at 225℃holding for 30 minutes will get 59.5 HRC center hardness, 219.9kg-cm fracture torque value.
There is decarbonized zone on the surface of austempered specimen, including CM1 and CM2 products, so the fatigue life of all the specimens didn’t reach the goal of 20,000 cycles fatigue life. The follow-up study will be to do with the issue of surface treatment, such as surface decarburization and shot peening. It will be valid for promoting the fatigue life.

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