- 期刊
中碳鉻鉬鋼AISI4140之雷射表面硬化處理
Laser Surface Hardening of AISI 4140 Steel
摘要
本研究旨在探討雷射表面硬化處理對鉻鉬鋼之組織與機械性質之影響。研究方法為將AISI 4140中碳鉻鉬鋼製作成具圓截面之拉伸試桿，以原有之熱軋延狀態以及經淬火回火處理後，分別利用雷射進行表面硬化處理。雷射參數為：連續式CO2雷射、功率1000W，配合三種掃描速度（5mm／sec、7.5mm／sec以及10mm／sec），於試桿圓周表面以等間隔方式（45°）沿軸向掃描八道。將雷射處理後之試桿分別進行拉伸試驗、破斷面觀察、橫截面微硬度量測以及金相組織觀察等。研究結果顯示：AISI 4140鋼經雷射處理所得之表面硬化層為麻田散鐵組織，微硬度呈大幅的提升，達到Hv 666－801；硬化層深度則達到0.88－1.65mm；不論是熱軋延狀態或淬火回火狀態，雷射表面處理使其降伏強度與抗拉強度值均為提高，但增幅隨雷射掃描速度的增加而減緩。經雷射處理之試桿的拉伸破斷面型態由延性破壞變為脆性破壞模式。
並列摘要
The effects of laser surface hardening on mechanical properties of AISI 4140 steel have been studied. The laser surface hardening were carried out with continuous CO2 laser beam which scanned eight times as axial direction on the AISI 4140 steel surface of a circular cross-section, and the parameters of laser hardening were power of 1000 W and three scanning rate of 5, 7.5 and 10 mm/sec respectively. Two types of heat treatment, either hot rolling or quenching-tempering was performed prior to laser hardening. The microstructure, surface hardness, hardened depth, and tensile properties of the specimens were investigated. It was found that the structure of laser hardening layer was martensite. It was also detected that the hardness of AISI 4140 steel was promoted apparently to Hv 666-801, and the hardened depth was attained to 0.88-1.65 mm. It had significant effect on the tensile strength of the hardened specimens as either hot rolling or quenching-tempering. Furthermore, the fracture type was turned brittle into ductile when the laser hardened specimen was broken during the tensile test.