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CRADA NFE-08-01671 – Materials for Advanced Turbocharger Design

PI – Philip J. Maziasz, ORNL and Pat Pattabiraman, Honeywell

Oral – Wednesday, May 11, 2011

Project ID – PM038

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Overview

• Project began – September, 2009

• Project ends – September, 2012

• Project is <50% complete, and extension will be negotiated with Honeywell next year due to expanded commercialization opportunities

Timeline

• Total Project Funding

• DOE Share – 50%

• Honeywell – 50%

• FY10 DOE Funding - $300,000

• FY11 DOE Funding - $300,000

Budget

• Changing internal combustion engine regimes

• Long lead time for materials commercialization

• Durability – Current commercially viable materials limit engine efficiency by limiting peak cylinder pressure and exhaust temperatures

• Cost

Barriers

Partners

• Honeywell’s suppliers for turbocharger components• Materials producers for components

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Objective

This CRADA project is relevant to a key technical gap in Propulsion Materials that supports the following Advanced Combustion Engine goal:

2015 Commercial Engine – Improve Thermal Efficiency by 20% over current baseline efficiency

Technical Objective – Higher temperatures (>750oC, diesel, >950oC gasoline) exceed the strength and temperature capability of current materials, particularly cast-iron for turbocharger housings

Impact – Turbocharger housing and other components with more temperature capability and strength will enable higher, sustained operating temperatures. Stainless steel turbo-housings will also reduce weight and retain exhaust heat relative to cast-irons

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Approach

• Honeywell and ORNL have considered current materials used for hot (turbine) and cold (compressor) portions of current turbocharger systems

• Honeywell and ORNL have identified turbocharger housings and turbine-wheel/shaft assemblies as priority components for consideration with increased exhaust temperatures

• Cast austenitic stainless steels have more temperature capability as turbocharger housings than cast-irons

• Weld-joints between steel shafts and Ni-based alloy turbine wheels are the focus of residual stress studies

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Milestones

• FY2010 – new project• FY2011 – begin neutron-scattering residual-stress

measurements on wheel/shaft assemblies (Dec, 2010, done)

• FY2011 – complete long-term creep-rupture of cast CF8C-Plus stainless steels (Feb, 2011, done)

• FY2011 – Obtain new turbocharger housings of cast CF8C-Plus stainless steel (August, 2011, on-track)

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Technical Accomplishment – HFIR Neutron Scattering on wheel/shaft assemblies

Honeywell supplied wheel/shaft components from gasoline

turbocharger products

HTML User-Center at ORNL will use neutron-scattering to measure residual stresses in the weld-joint between Ni-based superalloy wheel and steel shaft

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Technical Accomplishments – Initial neutron-scattering experiments done at NRSF2

Incident Beam

Vertical Bank of Detectors

Translation & Rotation Stage

Incident Slit

Diffracted Slit

Transmitted Beam

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Technical Accomplishments – Upgrade Turbo-Housing to Cast Stainless Steel

Current SiMo cast-iron turbocharger housing for diesel engine product

ORNL developed CF8C-Plus cast stainless steel with more strength thanHK30Nb stainless alloy > 750oC.

Both have much more strength thanSiMo cast-iron above 500-600oC

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Tensile Test Temperature

Yield Strength Comparison

HK30-NbCF8C-Plus

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Technical Accomplishments – Upgrade Turbo-Housing to Cast Stainless Steel for More High-Temperature Creep Resistance

• CF8C-Plus cast stainless steel has significantly better creep-resistance than HK30-Nb stainless alloy at 700-900oC

•CF8C-Plus stainless steel cost is about 33% less than HK30-Nb alloy

Creep-Rupture Testing of Cast

CF8C-Plus stainless steel and HK30-Nb

stainless alloy at ORNL

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Creep Testing Conditions

Creep-Rupture Comparison (air)

HK30-Nb

CF8C-Plus

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Technical Accomplishments – Upgrading Turbo-Housing to Cast Stainless Steel Saves Energy in Manufacturing and Lifecycle Use

• Energy savings in manufacturing and in fuel-efficiency during vehicle lifecycle are compared for CF8C-Plus steel and HK30 alloy

• Using CF8C-Plus steel for turbo-chargers has significant lifecycle energy savings

Primary Energy for Making Material, Component and for Lifecycle Use of CF8C-Plus steel, HK30 alloy and Ni-based 625 superalloy

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Calculations byS. Das, NTRC, ORNL

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Collaboration and Coordination with Other Partners

• Honeywell coordinates with its materials suppliers to provide standard and new prototype turbocharger components

• ORNL provides substantial collaboration between this project and Residual-Stress User Center at the High Temperature Materials Laboratory (HTML) for neutron-scattering experiments at HFIR (C. Hubbard and T. Watkins)

• ORNL provides collaboration between this project and the NTRC for economic and energy modeling calculations and analysis (S. Das)

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Future Work – Produce stainless steel turbo-housings, test materials for other components and continue residual stress experiments

• Honeywell will work with stainless steel foundry to produce turbocharger housings of CF8C-Plus steel

• Expand properties testing for turbine housing and wheel alloys to include oxidation and fatigue

• Examine effects of processing variables on residual stresses in weld-joints of wheel/shaft assemblies

• Examine residual stresses in critical locations of turbo-charger housings made of SiMo cast iron and CF8C-Plus cast stainless steel

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Summary

• Honeywell and ORNL have initially assessed the effects of higher exhaust temperatures on turbocharger materials and components, and prioritized several for more in-depth study

• Residual stresses in weld-joints between Ni-based alloy turbine wheels and steel shafts are a concern that is being addressed with neutron scattering experiments wheel/shaft components at the HTML at ORNL

• Long-term creep-rupture data has shown that CF8C-Plus cast stainless steel has more performance than HK30-Nb stainless alloy as an upgrade for turbo-housings at 700-900oC

• Economic and energy savings studies show that CF8C-Plus steel is 33% less costly, and produces component manufacturing and vehicle use lifecycle energy savings relative to HK30-Nb stainless alloy for turbocharger housing applications