17-4 PH不銹鋼雷射披覆銲件之機械特性探討

Mechanical Properties of Laser-cladded 17-4 PH Stainless Steel

10.6409/JMSE.200503.0051

吳寭政(Hsien-Cheng Wu)；陳鈞(Chun Chen)

17-4 PH不銹鋼 ； 雷射披覆 ； 機械特質 ； 氫脆 ； 17-4PH stainless steel ； laser cladding ； mechanical property ； hydrogen embrittlement

材料科學與工程

37卷1期（2005 / 03 / 01）

51 - 55

繁體中文

本研究應用與雷射同軸之送粉噴嘴，進行17-4 PH不銹鋼之雷射披覆處理，並探討經後熱處理披覆試片之拉伸機械性質、疲勞裂縫成長特性及缺口拉伸強度等。經H900 (482℃/1hr+AC)處理披覆試片之強度，均較經固溶+H1150M (760℃/2hr+AC+621℃/4hr+AC)處理之披覆試片或母材爲高，但其伸長率較低。在衝擊韌性方面，經H900之披覆試片，衝擊值較經固溶+H1150M處理之母材或披覆試片爲低。疲勞裂縫成長試驗結果顯示，母材經固溶+H1150M熱處理試片之裂縫成長速率(da/dN)最慢，次爲經H900之披覆試片，而母材經固溶+H900處理試片之da/dN最快。H900披覆試片對氫脆敏感性，高於經H1150M處理之披覆試片。H900披覆試片隨氫氧壓力增加，缺口拉伸拉伸強度迅速降低；H1150M披覆試片之缺口拉伸强度隨氫氧壓力增加僅少量降低，此氫脆敏感性的降低，回復沃斯田鐵(Reverted austenite)的大量生成爲其主要原因。

An investigation was conducted to evaluate the mechanical properties of laser-cladded 17-4 PH specimens via a coaxial powder feed nozzle. Various postweld heat treatments were also performed on laser-cladded specimens, and the results of mechanical testing were compared to those of the base plate. Tensile and yield strengths of cladded specimens after a H900 treatment (482℃/1h) was higher, but with lower ductility and impact toughness, than those of the base plate or cladded specimens subjected to solution and H1150M (760℃/2h+621℃/4h) treatments. Laser-cladded and H900-treated specimens exhibited the fatigue crack growth rate higher than H1150M-but lower than H900-treated base plates. Results of notched tensile tests in hydrogen indicated that laser-cladded specimens were more susceptible to hydrogen embrittlement in H900-than in H1150M-treated conditions. The reduction of notched tensile strength with increasing the hydrogen pressure was quite obvious in the former and seemed insignificant in the latter. The extensive formation of reverted austenite in H1150M-treated specimens was responsible for the reduced susceptibility to hydrogen embrittlement.