LASER CLADDING HIGH PERFORMANCE MATERIALS FOR SMALL MODULAR REACTOR SYSTEM COMPONENTS John M. Haake Titanova, Inc Why Lasers • Laser generates controllable optical energy that can be used to modify materials Photons = Pure Energy – Controllable in.................. There are NO Electric or Magnetic fields •Power Insensitive to electric or magnetic fields •Direction Photons do not interact no matter how many you have •Only optical interactions – Energy Type •Radiation = Instantaneous heating = instantaneous Control Why Lasers Now • Most cost effective heat source for low dilution Weld Overlays [WOL] • Very high powers = high deposition rate • Lower costs • Flexible options – In-Situ Temperature control – In-situ beam shape control • Many options with the same Laser Focus Configuration – Direct Diode Top-Hat Line Source 17 X < 0.4 mm line @ focus - 200 mm Process Axis for heat treating, cladding, paint stripping, surface melting, composite manufacturing Process axis for autogenous welding, wire feed welding and brazing The line source is necessary to achieve thin flat low dilution clads. 4 Advanced Fiber Coupled Diode Laser Optical components Benefits of Diode Laser Cladding • Welded 100% dense = No porosity • Very Low dilution = High Corrosion resistance • Very Low dilution = Elimination of solidification cracks • Small heat affected zone = less distortion • High quench rates = finer grain structure = higher corrosion potentials • Line Source allows for much wider thinner clads • Less Preheat required • Much smoother clads = less post machining • High Deposition Efficiency [ > 20 lbs./hr. ] • Highly controllable [Laser Tempering] • Smaller wavelength=higher photon energy = More absorption – Enables Hot and Cold wire feed cladding – Enables strip cladding – Enables spray and fuse cladding • Small Size – Enables in-field cladding 6 Methods for Laser Cladding • Powder cladding – Preplaced and Collinear • • Thermal Spray and laser fuse Wire feed cladding – Vertical wire feed cladding • Hybrid processes – Cold wire feed – Hot wire feed • LISI - Laser Induced Surface Improvement 7 Diode Laser Wire Feed Cladding Cold Wire Wire Dia. = 0.045” Wire feed Speed = 15 in/min Process speed = 3.3 mm/sec 0.45 lbs/hour Diode laser Wire Feed Cladding Advantages Easy to implement Amenable to portability Out of position cladding possible Disadvantages of Cold Wire feeding Higher dilutions larger HAZ Slower speeds Potential Solution HOT WIRE FEEDING 8 Titanova Hot Wire Results Inconel 625 Wire Cr 20.63%, Fe 0.1 % Ni 66.9%, Mo 8.3% Inconel 625 0.045” wire 200 ipm Wire feed speed, 8 mm/sec surface speed 0.080” (2mm) thick Compatible with Power Feed Cladding 5 – 6 lbs /hour deposition Laser Fused Dilution >99% efficiency @ 4000W 15- 25 lbs an hour with 10000W Cr 20.5% Range 14.6 – 20.8 Fe 7.6% Range 0.1- 14% Ni 59.1% Range 66% - 44% Mo 7.5% Range 8.1-5.1 % 9 EPRI Diode Laser Weld Overlay Investigation EPRI - Scope of Work Recap • Perform test matrix to develop hot wire laser welding overlay techniques and parameters for temperbead • Developed low dilution welding parameters for application on the Stainless steel side of the WOL • Performed WOL on LAS/SS test coupon • Perform the following testing on the WOL – Metallurgical examination – UT examination Completed WOL 6 lbs/hr Deposition rate Three weld layers Inspection of WOL • Metallurgical Examination – Lack of bond – Presence of un-temper martensite – Any other detrimental metallurgical features • UT examination •Metallurgical examination revealed no defects •UT examination revealed no lack of bond or other weld defects Development of Temperbead Welding Parameters – Hot Wire Laser WOL Traverse 3 - T3 600 500 47.2 weld 4 Hardness (HK 0.5) 400 300 200 weld 3 40 30 weld 5 weld 6 weld 7 88 weld 8 weld 9 100 weld 10 Distance from Surface (mm) 0 0 0.2 0.4 0.6 0.8 1 1.2 Microhardness traverse at location T3 – Right hand toe of the weld SA-533 Location of microhardness traverses Left hand toe Knoop indentation Laser Tempering the WOL The Same Lasers can be used to temper the WOL • On the fly beam shaping • In-situ Temperature Control Overview Laser Beam Shapes - Clad Profile Comparison Dilution held constant 23 3 q q Wetting angle Gaussian shape beam – round spot 24 q Rectangular shape beam More desirable 3 25 q Line shape beam Clad Morphology – Spot vs. Line Source Dilution held constant Gaussian Profile Rectangular Profile • Less risk of entrapped pores Line Profile Laser Cladding - What is Desirable from a High deposition Rate Perspective • THIN, FLAT, LOW DILUTION clads • Increased deposition efficiency without loss of good morphology • WOL Material insensitivity • Base material insensitivity • Gas coverage insensitivity • Base material shape insensitivity • Base material position insensitivity • Edge definition – inside and outside edges • Tempering Toe of the Weld • In Situ Repair - Zero defects • System robustness 18 Proposed WOL weld puddle and HAZ control • The Primary laser is the “work horse” it melts the clad material and creates the weld puddle • The Secondary low power laser is used to influence the weld puddle shape • Maintaining a molten state is a strategic location longer • Affecting surface tension properties in a beneficial way • Tempering the toe of the previous overlay • Maintaining the S length Patent Pending 19 Separation of Complex Variables Robust High power Laser cladding systems Primary Laser • Maximized High power lasers WELD puddle creator • Maximized deposition rates • Extensive peripheral cooling • Expensive Cladding nozzles Customized • Peripheral Cooling • Gas coverage $ Secondary Laser WELD puddle manipulator Secondary lower power laser Optimized for flexibility Optimized for beam manipulation Independent from Primary laser Not collinear with Primary laser Inexpensive Patent Pending 20 Examples of 4000W Line Cladding Source with Varying Secondary Laser Power near Right Hand Toe 0 Watts Secondary Laser on Right 110 Watts 36:1 210 Watts 19:1 632 Watts 6:1 Not optimized 1050 Watts 4:1 Patent Pending 21 Potential Benefits of In-situ Puddle Shape control • • • • • • • • • • • • • • • • Increase deposition rates = cm2/W Improved morphology [flatter thinner clads] Lowering dilution [ Less heat for tie in] Clad material independence Based material independence Cover gas independence Base work piece shape or position independence In situ defect mitigation [fixing blow holes] Outside Edge definition Edge definition around holes Inside fillet definition In Situ defect mitigation Thinner clads with less defects Control of solidification cracking issues Improving wire feed laser cladding 3D build up Patent Pending Conclusion • Diode Lasers are the best heat source for Low dilution Cladding which inherently overcomes many issues associated with WOL’s. • Diode laser can produce excellent first pass chemistries with thin deposition layers • Diode Laser powers are such that >20 lbs./hr. are now possible • Diode Laser are inherently controllable enabling in-situ temperature control • The same laser can be used to Temper the previous pass thus making temper bead welding much easier to implement. Thank You John M. Haake [email protected] 636-487-0060
© Copyright 2024 ExpyDoc
