Materials & Advanced Manufacturing (M&AM) High Mn, High Al Steels for Thick Plate Applications M ATERIALS & A DVANCE M ANUFACTURING (M&AM) T ECHNICAL S ESSION A UGUST 7-9, 2018 - N OVI , M ICHIGAN Katherine Sebeck, PhD Krista Limmer, PhD Ian Toppler Bryan Cheeseman, PhD Matt Rogers Daniel Field, PhD U.S. Army TARDEC US Army Research Lab Warren, MI Aberdeen, MD LTC Ryan Howell, PhD William Herman, PhD US Army PEO GCS General Dynamics Land Systems Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions Warren, MI Sterling Heights, MI DISTRIBUTION A. Approved for public release: distribution unlimited. OPSEC #1061
Materials & Advanced Outline Manufacturing (M&AM) • Background and Motivation • Industrial Pour Outcomes • Rolling and Forging of Plates • Heat Treatment • Plate Characterization • Welding • Machining • Conclusions and Continuing Work Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
Materials & Advanced FeMnAl - Collaborators Manufacturing (M&AM) Funding Acknowledgements: Advanced Vehicle Power Technology Alliance (AVPTA) "Extended Enterprise" Joint DoE/DoD Effort FY17 Army ManTech “ Manufacturing Processes for Lightweighting Heavy Combat Vehicles” Individual Acknowledgements: Jared Wysocki, Ed Barshaw(PdM Abrams) Craig Niese, Chris Karas (GDLS) Fred Fletcher (Arcelor Mittal) Zhili Feng, Dean Pierce (ORNL) Jim Kane, Joe DeGennova (EQS) Matt Sinfield (ONR) Carl Johnson (TARDEC) Ryan Nicol, Jeff Krzeszak, Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
Materials & Advanced What is FeMnAl? Manufacturing (M&AM) • Al loys contain between 10-30 wt.% Mn, 3-12 wt.% Al, 0-1 wt.% C, 0-1 wt.% Si – Al, Si, and C reduce the density 2 ways – direct substitution into the matrix and matrix dilation • Also may contain Cr, Ni, Mo, Nb, V Current target: 28Mn-9.5Al-0.9C-1.0Si-0.5Mo • • FeMnAl evolved from Hadfield steels (Mangalloy) of Fe-13Mn-1.2C & FeAl alloys – Intermittently investigated going back to 1943 – Adding Mn to Fe-Al alloys to improve ductility • Navy investigated as alternative to Cr and Ni austenitic stainless steels – Emphasis on corrosion resistance, rather than mechanical properties • Age hardenability discovered in late 1960s – High hardnesses opened possibilities for additional applications • Recent works emphasizing thin sheet for automotive body frames Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
Materials & Advanced Programmatic Drivers Manufacturing (M&AM) • Weight and Performance – 7.8 g/cc vs 2.7 g/cc (steel vs Al) – Space considerations – Strength/Density vs Threat Performance/Density • Going thinner is not necessarily better, or possible – Rigid structures and underbody required in military vehicles • Automotive lightweighting is driven by meeting fuel economy standards • Army lightweighting is driven by meeting performance requirements for changing threats, new equipment, and maintaining logistic supports – Army bridges, NATO rail car, and highway equipment transport trailer (HETT) designed for 70T capacity – Weight reduction needs driven by “hard points” instead of $/lb motivation Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
Materials & Advanced Steel Processing Steps Manufacturing (M&AM) Machining and Raw Materials Melt Practices Ingot Pour Pre-rolling Rolling Heat Cut to Plate Assembly processes Treatment •Ferromanganese vs •Sequence of •Ladle superheat •Pre-heat •Cutting Type •Surface grinding electrolytic Mn additions temperature •Mold flux •Feed Rate •Painting •Solutionizing •Drilling •Target chemistry •Ar stirring •Heating •Mold geometry •Forging •Temperature •Welding time/method •Cover gases •Gate sizes •Grinding •Time •Single vs double •Ca treatment •Mold preheat •Ageing conversion •Ladle refractories •Quenching •Temperature •Descale passes •Melt time •Volume per pour •Time •Edging Passes •Target •Lancing •Multi-stage cycles •Cooling temperatures •Removal timing Items in black are known values •Pickling •Cooling rate •Piece width Items in green are preliminary Items in white are to be determined Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
Materials & Advanced Industrial Pours – Teeming Flux Manufacturing (M&AM) • Typical steel fluxes have high SiO 2 content to ensure good flow, coverage • SiO 2 reacts with Al to form Si and Al 2 O 3 – [Al] + SiO 2 -> [Si] + Al 2 O 3 Ingot # Flux – Resulted in significant Al losses in first heat attempt 1 Typical SiO 2 • Compared 4 different fluxes 2 High C 3 1:1 Lime alumina 4 Soda lime alumina +CaF A (higher CaF) 5 Soda lime alumina +CaF B Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
Materials & Advanced Industrial Pours – Quality Control Manufacturing (M&AM) Pour Date Mn Al C Mo Si Fe (bal) July 17 28.8 9.1 1.01 0.5 0.6 59.9 (ICP) July 17 29.19 9.9 0.92 0.5 0.96 58.53 (OES) Feb 2018 29.7 9.6 0.84 0.54 0.8 58.2 (OES) Due to the high alloy content and shrinkage behavior, large ingot sizes may not be possible • – 34”x47” ingot fractured during cooling • Chemistry analysis in production typical is performed with Optical Emission Spectroscopy – Tends to overestimate Mn, Al compared to Inductively Couple Plasma Spectroscopy (ICP), underestimates C content Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
Materials & Advanced Rolling Temperature Manufacturing (M&AM) 1950°F (1065°C) 22 Aug 2017 2128°F (1121°C) 12 Oct 2017 • Compressive testing via Gleeble 2200°F (1202°C) • Flow stress drops off rapidly between 1175°C to 12 April 2018 1200°C during tensile deformation Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
Materials & Advanced Forging Effects Manufacturing (M&AM) A1131-5: Forged then A1131-1: Rolled to 1.5” • A1132-4B: Forged between 2150 – 2200° F rolled to 1.5” plate – plate – soak at 1950° F • Improved surface finish compared to as-cast ingot A1132-5 soak at 2150° F – Similar edge cracking magnitude Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
Materials & Advanced Forging Effects - Microstructure Manufacturing (M&AM) • Right: Forged, as rolled (1”) • Left: As rolled (1”) • Forged microstructure shows more homogenous grain shape, fewer elongated stringers • Similar grain size distribution through thickness • As rolled hardness: – Forged – 201 BHN – As-cast – 251 BHN Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
Materials & Advanced Heat Treatment - Ageing Manufacturing (M&AM) Al Al [Fe, Mn] Al Al [Fe, Mn] [Fe, Mn] C [Fe, Mn] [Fe, Mn] Al Al [Fe, Mn] Al Al κ -carbide cubic perovskite crystal Micrograph of wrought FeMnAl base metal, showing two small islands of ferrite in a predominately austenitic microstructure structure (E2 1 ) • Homogenize/Austenitize and rolling preheat between 1000°C to 1150°C (~1850°F - 2100°F) Water quench preferred (no martensitic transformation) • Age <550°C (~1000°F) • Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
Materials & Advanced Heat Treatment – Single Stage Aging Manufacturing (M&AM) • As-Rolled (HB) • Hot rolling to gauge followed by air cooling • Initial hardness within target hardness range • Hardness increases with time • Solution Treated & Quenched (STQ) • 1922 o F (1050 o C) STQ: 195 ± 4 BHN STQ+30hr: 320 ± 5 BHN STQ+30hr: 320 ± 5 BHN • 2 hours • Water quench to room temperature • Peak/Target occurs at ~20 hrs • Aging • 1000 o F (538 o C) • Variable times Background | Industrial Pours | Rolling & Forging | Heat Treatment | Plate Characterization| Welding| Machining| Conclusions UNCLASSIFIED//DIST. A
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