Laser cladding and hardfacing
Laser assisted metal deposition to produce wear resistant overlay
Laser assisted surface modification and cladding to increase wear resistance for mining, mineral and food processing, and power generation.
The challenge
Many components used in power generation such as steam regulating valve heads and seats are subjected to high pressure steam and particle impingement erosion. Premature wear results in inefficient power generation, steam loss and eventual expensive shutdown of the power plant. Client approached CSIRO to develop wear resistant hardfacing overlay to reduce wear and deposition process in order to extend service life. Another work relates to extensive abrasive wear in the body of the break-in picks used in resource sectors. Premature wear in the pick body forces expensive shutdown of shearer drum for replacement.
Steam valve head heavily eroded by high temperature erosion. Refurbished by laser cladding with cobalt base superalloy overlay.
Our response
The work needed to use appropriate alloy deposits on the face of the workpiece. Laser cladding process was used to produce fusion bonded homogenised overlay with minimum dilution and heat affected zone in the workpiece.
Break-in pick heavily worn out at only 8 hours after operation. New pick body which is laser clad with tungsten carbide and cobalt base overlay.
The results
High power laser beam was used in conjunction with metal powder to develop cladding process parameters and to deposit hardfacing overlay free of defects and cracking with minimum dilution and heat affected zones in the workpiece. Coupon samples were produced and representative wear tests were utilised to assess the wear performance in the laboratory. Several real components were received from clients to deposit wear resistant overlay. CSIRO provided the cladding services for field evaluations. Plant engineers assessed service performance and this provided longer service life well beyond designed operating service life.
A) Cross section laser clad overlay over a test sample showing small HAZ and minimum dilution. Arrow indicates interface with no defects. B) Typical weld overlay showing extensive dilution and distortion.