Effect of processing conditions on the corrosion performance of laser surface-melted AISI 440C martensitic stainless steel

Abstract Laser surface melting of AISI 440C martensitic stainless steel was achieved using a 2.5-kW continuous wave Nd:YAG laser. The pitting corrosion behavior of laser surface-melted specimens processed under different processing conditions in 3.5% NaCl solution at 23 °C was studied by potentiodynamic polarization technique. The corrosion resistance of all laser surface-melted specimens was significantly improved, as evidenced by a shift from active corrosion to passivity, a wide passive range and a low passive current density. The pitting potential of the laser surface-melted specimens P08-440C-25 (laser power=0.8 kW, scanning speed=25 mm/s) and P12-440C-25 (laser power=1.2 kW, scanning speed=25 mm/s) was increased to 260 and 200 mV (SCE), respectively, and was much higher than that of the conventionally heat-treated AISI 440C. The pitting corrosion characteristics of the laser surface-melted specimens were strongly dependent on the processing conditions which resulted in different microstructures. The enhanced corrosion resistance was attributed to the dissolution or refinement of carbide particles and the presence of retained austenite. The amount of carbides in the melt layer, which indirectly determine the Cr content in solid solution and hence, the corrosion resistance, was related to the amount of C remaining in solid solution and to decarburization. The pit morphology of the laser surface-melted specimen was also studied.

[1]  Y. Miyata,et al.  Effect of Retained Austenite on Corrosion Performance for Modified 13% Cr Steel Pipe , 2001 .

[2]  J. Bello,et al.  Laser surface treatment and corrosion behaviour of martensitic stainless AISI 420 steel , 1992 .

[3]  R. Colaço,et al.  Effect of the processing parameters on the proportion of retained austenite in laser surface melted tool steels , 1998 .

[4]  E. Mccafferty,et al.  Corrosion Behavior of Laser‐Surface Melted and Laser‐Surface Alloyed Steels , 1986 .

[5]  R. Colaço,et al.  Phase selection during laser surface melting of martensitic stainless tool steels , 1997 .

[6]  Peter R. Strutt,et al.  Laser surface melting of high speed tool steels , 1978 .

[7]  R. Colaço,et al.  Influence of the processing conditions on the abrasive wear behaviour of a laser surface melted tool steel , 1999 .

[8]  J. Damborenea,et al.  Corrosion behaviour of steels after laser surface melting , 2000 .

[9]  H. Man,et al.  Cavitation erosion and pitting corrosion behaviour of laser surface-melted martensitic stainless steel UNS S42000 , 2000 .

[10]  R. Colaço,et al.  Phase selection during solidification of AISI 420 and AISI 440C tool steels , 1996 .

[11]  Osman T. Inal,et al.  Laser surface melting and alloying of type 304L stainless steel , 1995 .

[12]  H. C. Man,et al.  Cavitation erosion and pitting corrosion of laser surface melted stainless steels , 1998 .

[13]  Leif Åhman,et al.  Microstructure and its effect on toughness and wear resistance of laser surface melted and post heat treated high speed steel , 1984 .