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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.

Two metal objects of steam valve, before and after photo. First object cylinder plus upside down cone on top. Indication of erosion and external damage. After shot same sized image after refurbished by laser cladding image smoothed over with no indication of erosion or damage
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.

Two metal cylinder like objects with cone attatched. First (before image) black with rough surfaces second image (after) after laser clad enhancement, has polished and smooth look to it
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.

Two images of test samples highlighting dilation and defects. Image A indicates minimal damage and image B indicates extensive dilution
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.