Centre for Laser Processing of Materials (CLPM)

Overview

Enhancing service life by surface treatment and recovering component after post damage could have significant economic benefits. Die tool costs 10% of cast part. Repair and refurbishment are increasingly common practices, seeking to maximize unit lifetime, availability and profitability.

Key Features

• Repair is possible without preheating of the components/tools
• Low heat input to the component, so less damage 
• Narrow soft zone created with relatively high hardness 
• Fully automated and repeatable
• Precise deposition and less post processing

Potential Applications

• Pressure die casting tools 
• High Temperature Extrusion tools
• Hot Forging tools 
• Hot forming and Punching tools

Intellectual Property Development Indices (IPDI)

• Successfully completed testing of repaired PDC tools on real-time conditions (Case study)

Microstructure of Post Clad Heat treatment

Microhardness comparison at different conditions

Overview

Modified 9Cr-1Mo (P91) steel finds its usage in high temperature applications such as in supercritical and ultra super critical power plants. The weldability issues in P91 steel such as formation of delta ferrite in the fusion zone reducing the creep properties, hydrogen induced cracking due to high hardness in as-welded condition and Type-IV cracking in the intercritical zone away from the Heat Affected Zone (HAZ) are expected to be obviated through low heat input welding technique. Autogenous laser welding a low heat input technique when applied on 6 mm thick P91 steel plates using high beam quality (Gaussian,K>0.96) DC035 slab CO2 laser using a focal spot size of 180 µm could successfully address the above stated challenges.

Key Features

• Welds free from both hot and cold cracks and also fusion zone free of delta ferrite and no intercritical soft zone. 
• The welds have 100 % joint efficiency with failure away from the weld in tensile testing and the welds have sufficient bend ductility.

Potential Applications

• Power plant 
• Nuclear industry

Intellectual Property Development Indices (IPDI)

• Performance and stability are validated at coupon level

Laser weld Macrograph-P91 steel

Laser Welded 9Cr1Mo plates after bend test

Major Patents / Publications

Major Publications

1. B. Shanmugarajan, G. Padmanabham, Hemant Kumar, S.K. Albert and A.K.Bhaduri, “Autogenous laser welding investigations on modified 9Cr-1Mo (P91) steels”, Science & Technology of Welding and Joining, Vol.6, No.6, 2011, p528

Overview

Heavy engineering industries use various big and expensive components like Turbo shaft. A localize wear or other damage on a critical location can lead to scrapping the entire component. A turbo shaft is such component which gets wear on the bearing seat area. Refurbishment was done by removing the damaged layer and rebuilding a new clad layer using laser clad deposition method. A Cobalt based powder was chosen for the refurbishment to improve the wear properties and enhance the life of the refurbished component. Defect-free coating of 1.8 mm thickness across the contour of seating area was produced by diode laser cladding with following characteristics: 

Key Features

• Negligible porosity 
• Controlled heat input 
• Minimal heat affected region 
• Precise and controlled process 
• No distortion

Potential Applications

• Turbo shafts 
• Steam turbine and gas turbines

Intellectual Property Development Indices (IPDI)

• Refurbished shaft was used by end user and demonstrated excellent performance

Repair Process

As-coated Surface & Finish Grinded Surface

Overview

In power plants, degradation of various components like coal nozzle tips, boiler tubes, burner spreaders, etc, due to various modes of wear, erosion and corrosion, is a common problem leading to their replacement during maintenance schedules. Such tribological systems, working in high temperature aggressive environments, require suitable surface modification solutions for life enhancement.

Key Features

• Highly controlled process 
• Flexibility to adopt the process for different components 
• Selective clad coating where needed 
• Excellent metallurgical bond between coating and surface 
• No post clad heat treatment required

Potential Applications

• Baffle plates 
• Boiler tube 
• Burner spreaders etc

Intellectual Property Development Indices (IPDI)

• Field trial in an actual power plant showed negligible wear after 15 month of service

Erosion in Burner tip plates

Burner tip plates after 15months of field trials showing intact laser cladded plate and worn out uncoated plate at top

Major Patents / Publications

Major Publications

1. “A novel method of pulsed laser cladding for effective control of melting of WC particulates in NiCr-WC composite coatings” Manish Tak, SM Shariff, Vikram Sake, G Padmanabham, Proceedings of 31st International Congress of Laser & Electro optic (ICALEO), p515-523, 2012
2. “Characteristics and erosive wear performance of Ni-Cr based coatings on SS-310 steel by diode laser cladding and weldoverlay processes”, Proceeding of International conference on Surface Modification Technologies (SMT-23)

Overview

Grey cast iron finds extensive applications in the Glass mould industries and automotive industries for making of components like dies, gears, links, cylinder block, cylinder head, clutch plate etc. Many times, the size of the cast component is large and a small localize wear can lead to scrapping the entire component. Repair of cast iron has been very challenging due to presence of free carbon in the form of graphite flakes which forms COx gases during deposition and these gases get entrapped during the deposition process resulting in porosity. Transverse cracking is another deterrent in repair which occurs due to interfacial stresses associated with formation of hard and brittle heat affect zone. Laser cladding due to its advantages like minimal and controlled energy input can minimise the heat affected zone and minimise the formation of COx gases. Repair solutions with or without pre-heating were developed successfully.

Key Features

• Negligible porosity 
• Crack free deposition 
• No distortion 
• Minimal heat affected region

Potential Applications

• Glass Mould Dies 
• Cylinder Heads 
• Cam Shafts 
• Gear Boxes 
• Heavy engineering equipment and machine beds

Intellectual Property Development Indices (IPDI)

• Performance and stability are validated at laboratory scale
• Prototypes are generated 
• Field trials are underway

Repaired Area

Cross-sectional hardness profile of laser clad repaired grey cast iron

Overview

Hemming beds or forming dies are widely used in the automotive industry. The edges which are used for forming are subjected to high wear and require hardening to improve the bed’s life. Laser hardening provide an excellent control on the energy input enabling hardening of cast iron without melting. The surface temperature regulation system available at ARCI provides added control while processing 3D contours as well negligible change in the surface finish can eliminate the requirement of any post hardening machining.

Key Features

• Selective and localised hardening process 
• No coolant or quenching medium required 
• Uniform hardened layer throughout the processed area 
• Negligible change in the surface roughness 
• Compressive stresses in the hardened region 
• Automation possible, No human errors 
• Case depth 0.8 - 1.2 mm with ~55HRc uniform hardness throughout the bed Material (GGG70L Nodular Cast Iron)

Potential Applications

• Hemming beds and Forming dies made of cast iron and steels

Intellectual Property Development Indices (IPDI)

• Laser hardened hemming beds were used by end user with excellent performance compared to flame hardened beds

Hemming Bed

Cross-sectional hardness profile of laser hardened Hemming bed (Material: Nodular cast iron GGG70L)

Overview

The proposed AUSC boiler will have IN617 and IN625 parts / components in very high volume. However, nickel-based alloys are known as difficult-to-machine materials due to high strength and low thermal conductivity that make the cutting forces and cutting temperature very high leading to a short tool life. Hence, machining cost of these parts will be very high. Laser Assisted Machining (LAM), the material is locally heated and softened by an intense laser source prior to material removal, without melting or sublimation of the work piece as depicted in fig. This enables the difficult-to-machine materials to be machined more easily and with low machine power consumption, which leads to increase in material removal rate and productivity.

Key Features

• Softening of the material by heating
• Reduction in tool forces
• Better finish
• Lower tool wear

Potential Applications

• Component made of hard to machine alloys
• Ni based super alloys, Ti-based alloys, ceramics

Intellectual Property Development Indices (IPDI)

• Performance and stability are validated at laboratory scale
• Scale-up and prototype module fabrication underway(Arial Narrow 10 pt – Not more than 3 bullet points of one line)

Laser Assisted Machining Setup

Overview

Crankshaft is one of the critical parts in an automotive engine, generally made of medium carbon steel requiring good wear resistance at contact areas (at bearings contact region and pin area) coupled with high load-bearing capacity. Laser surface transformation hardening process provides excellent surface finish with elimination of post-process machining requirement, no part distortion and easy adaptation to any dimension. Excellent control on the energy input leads to a uniform hardened layer across the component. A two-wheeler air-compressor crankshaft made of En18D material was successful;ly laser hardened and field trialled. Hardness in the range of 500 – 650 HV with a uniform case depth of about 300 μm was achieved. Net residual stress in the treated layer was ~ -310 MPa with 2-3% retained austenite. Laser hardened crankshafts showed 30% more life in field trials

Key Features

• Selective and localised hardening process
• No coolant or quenching medium required
• Uniform hardened layer throughout the processed area
• Negligible change in the surface roughness
• Compressive stresses in the hardened region
• Automation possible

Potential Applications

• Crank shafts
• Cam shafts
• Gears

Intellectual Property Development Indices (IPDI)

• Laser hardened crank shafts showed 30% more life in field trials

Laser Hardened Crank Shafts

Cross-sectional micrograph of laser hardened region

Major Patents / Publications

Major Publications

• Laser Surface Hardening of Crankshafts, SAE 2009-28-0053

Overview

High tensile steels are commonly used in aerospace, automotive, energy and general engineering sectors for various power transmission gears shafts, connecting rods propeller shafts, and heavy forgings such as rotors, shafts, disc etc. Such components can be damaged during operation due to wear at the contact areas and refurbishment of such components using laser cladding can save the replacement cost. Also, refurbishment technology can be beneficial in countering environmental concerns. Refurbishment technology using laser cladding for one of such component was developed that faces wear during operation due to relative movement between the contact surfaces. A post heat treatment was developed that can homogenise the clad and HAZ microstructure without creating dimensional and microstructural variation in the component. Microstructural, mechanical, and wear properties were found on par with the substrate. Component successfully completed the simulated field trial

Key Features

• Negligible porosity
• Controlled heat input
• Minimal heat affected region
• Precise and controlled process
• Special post heat treatment for improved properties

Potential Applications

• Pinion housing of Helicopters
• Components made of high tensile steels

Intellectual Property Development Indices (IPDI)

Major Patents / Publications

Major Patents*

• A patent is filed

Overview

AISI H13 tool steel is versatile material used in mould and die tools applications due to its excellent hot working property with good thermo-fatigue strength. Additive manufacturing of AISI H13 alloy leads to most efficient tooling application with possibility of complex designs with conformal cooling channels. AISI H13 being hardenable alloy with carbide precipitates is sensitive to rapid solidification involved in AM process. Hence, optimization of post heat treatment has been carried out to achieve the desired microstructure and required hardness and toughness in AM manufactured part. With developed knowledge on additive manufacturing of AISI H13 tool steel, a case study has been chosen with industrial partner and test the additively manufactured tool in real-time conditions.

Key Features

• Reduction in die temperature achieved between the two shots: In case study the core pin recorded a 15 to 20 % reduction in the die temperature.
• Reduced and delayed soldering effect: The soldering behaviour of the corepin with conformal cooling channel has improved. Surface porosity is reduced in size and numbers
• Reducing the number of rejections: Increase in production and reduced cost per part.
• Reduced Casting Cycle time: It has been confirmed that the cycle time has marginally reduced which results in increase of productivity.
• Tool Service life: Because of effective cooling the service life of the core pin has also increased as compared to the core pin without conformal cooling channel.

Potential Applications

• Pressure die casting tools
• High Temperature Extrusion tools
• Hot Forging tools
• Hot forming and Punching tools

Intellectual Property Development Indices (IPDI)

• Successfully completed testing of AM built PDC tools with conformal channels on real-time conditions (Case study)

Overview

Research to increase the efficiency of conventional fossil power plants by increasing the steam temperature and pressure has been pursued worldwide. The need to reduce CO2 emission has recently provided an additional incentive to increase efficiency. The main enabling technology in achieving the above goals has been the development of stronger high temperature materials. Solid solution and carbide strengthened Nickel based super alloys have been identified as candidate materials for Advanced ultra-supercritical (AUSC) boilers capable of operating with 760oC, 35Mpa steam. Laser hybrid welding is one of the potential fusion joining techniques developed for these alloys. Deep penetration capability of laser and edge bridgability of arc process enables processing of defect free joints at higher speed with acceptable mechanical properties. Laser hybrid welding process is AMSE coded and validated process.

Key Features

• Demonstrated laser hybrid weldability of 10mm thick Plates and Tubes at coupon level. 
• Defect free hybrid welds with minimal HAZ liquation. 
• 100% joint efficiency.

Potential Applications

• Power sector
• Aerospace
• Nuclear

Intellectual Property Development Indices (IPDI)

• Performance and stability are validated at coupon level

Single Pass Laser Hybrid weld cross-section

Set up of Laser Hybrid welding of Tubes

Overview

Due to high reactivity of titanium, especially at elevated temperatures, it reacts strongly with most atmospheric elements like, oxygen, hydrogen, nitrogen, etc. and gets embrittled readily. Hence, elaborate shielding arrangements are required while welding and often electron beam welding is preferred as it is done in vacuum. Laser Welding with simple and effective shielding arrangement has been proven to be techno-commercially feasible joining technique as compared to Electron Beam Welding.

Key Features

• Localised inert gas shielding set up. 
• Welded joint made with square and lip joint configuration on 4mm thick sheets with 100% joint efficiency.

Potential Applications

• Aerospace •
• Chemical industry 
• Medical industry

Intellectual Property Development Indices (IPDI)

• Performance and stability are validated at coupon level

Shielding arrangements for Laser welding

Laser Welded Ti6Al4V plates