Surface Hardening of a Vermicular Cast Iron Used for Integral Molding Valve Seat by High Power Laser

Surface hardening intergal molding valve seat of a vermicular cast Iron was done by Nd:YAG high power laser. The effect of laser parameters on microstructure, hardness and surface quality were conducted by scanning electron microscopy (SEM) ,optical microscopy (OM) and microhardness tester. The results show that The hardening layer of free defect can be obtained with suitable laser processing conditions. The shape of crescent can be observed in the laser hardening layer.The hardening layer consists of melted zone and heat-affected zone.Ledeburite, martensite and remainder austenite can be observed in the melted zone.The heat-affected zone consists of martensite and remainder austenite with retained vermicular graphite.Laser hardening layer has no-uniformity distribution of rigidity due to no-equilibrium calefaction and cooling.The defect of sunen disfigurement can be restrained by reducing heat-input in the ending zone.

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Surface Melting of Cast Iron With a High Power Laser Beam

MRS Proceedings ◽

10.1557/proc-8-517 ◽

1981 ◽

Vol 8 ◽

Cited By ~ 1

Author(s):

Ylva Nilsson

Keyword(s):

Cast Iron ◽

Laser Beam ◽

Partial Melting ◽

High Power ◽

Surface Hardening ◽

Beam Diameter ◽

High Power Laser ◽

Power Laser ◽

Scanning Rate ◽

Alloy Addition

ABSTRACTAn investigation is done on partial surface hardening and alloying on cast iron by means of a high power laser beam. Samples of cast iron have been covered with alloying material i.e. Ti, Cr, Si, V and Nb respectively. The samples were irradiated with a 2.5 kW laser beam. A partial melting of the surface occured and the alloys were dissolved. The carbide structure in the resolidified part was governed by the alloy addition. The carbide structure was metallographicly analysed. The effect of different parameters as beam diameter, scanning rate, power and alloy content have been investigated and the crack frequency has been evaluated.

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Thermal Shock on Cylinder Head Induced by High Power Laser

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.170-173.266 ◽

2012 ◽

Vol 170-173 ◽

pp. 266-269

Author(s):

Ming Pang ◽

Chang Zhen Liu ◽

Zhi Min Xie ◽

Guang Hui Xu

Keyword(s):

Cast Iron ◽

Thermal Shock ◽

Cylinder Head ◽

Ccd Camera ◽

Optical Microscope ◽

High Power Laser ◽

Power Laser ◽

Fatigue Specimen ◽

Graphite Cast Iron ◽

Scanning Electron

Experiment of thermal shock was conducted by laser on cylinder head of graphite cast iron. Infrared pyrometers were mounted on the top of the workbench to sample the transient surface temperatures. The high resolution CCD camera was employed to sample transient images of the cylinder head. Microstructure of thermal shocking specimen was characterized by scanning electron microscopy (SEM) and optical microscope (OM). Mechanical properties of thermal fatigue specimen were evaluated by hardness. Results show that microstructure and hardness are not obviously changed, which mean that cylinder head of graphite cast iron has performance stabilization within the rang of thermal shocking temperature.

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