evaluation of normalizing heat treatment to develop improved … · 2013-06-05 · background...
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Evaluation of Normalizing Heat Treatment to Develop Improved Properties inHeavy Section Pearlitic Iron
A DIS Project Proposal
June 6, 2012
Rick GundlachElement Wixom
Objectivej
Investigate the influence of super critical and g pintercritical heat treatments on the mechanical properties of heavy section ductile iron castings
(2 inches and greater)(2 inches and greater)
The combination of strength and ductility is so g ydifficult to achieve in the pearlitic grades cast in heavy sections
Focus on ASTM Grades 80‐55‐06 and 100‐70‐03
Backgroundg
• Normalizing is commonly employed in heavier sections to• Normalizing is commonly employed in heavier sections to obtain 80‐55‐06 properties
• DIS Project 46 ‐‐Mechanical properties in 3‐inch Y‐blocks
Tensile elongations of 6% never obtained, when a i i i ld h f 55 k i h dminimum yield strength of 55 ksi was reached.
•Intercritical heat treatments were even more effective in raising mechanical properties
Schematic Equilibrium Phase DiDiagram
Schematic of Heat Treatment CycleSchematic of Heat Treatment Cycle1600 UCT
1200
1400
deg.
F LCT
800
1000
pera
ture
,
400
600
Tem
p
2000 100 200 300 400
Ti i tTime, minutes
Intercritical Normalizingi i l l i l1545 F Intercritical plus Air Cool
Formation of Acicular Austeniteby Intercritical Heat‐Treatment
γ
FerriteFerrite γ
γ
Grain Boundary
Graphite
Intercritical Normalizingi i l l i l1545 F Intercritical plus Air Cool
METHODOLOGY
Numerous keel block legs from Project 46 are available, particularly those from the 3 inch Y blocks of the DOE study (Y blocks from 9 heats)
METHODOLOGY
from the 3‐inch Y‐blocks of the DOE study (Y‐blocks from 9 heats)
• Supercritical and intercritical heat treatments will be performed.
D t i th ti i t iti l t t‐ Determine the optimum intercritical temperature ‐ Hardness testing and metallography will be performed
• Heat treat Keel block legs according to parameters derived above and perform mechanical testing and metallography
• Fractographic inspection of the broken tensile specimens will be performed on selected test barson selected test bars.
• Heat treatments that successfully produced the minimum properties of Grade 80‐55‐06 will be defined.
ScheduleSchedule
• Element Wixom has DOE test materials on hand DIS members are• Element Wixom has DOE test materials on hand. DIS members are encouraged to provide additional test bars.
• Within 6 weeks, the 3‐inch Y‐blocks and any additional materials received will be subjected to heat‐treatment experiments.
• Evaluate the properties of the heat‐treated materials and determine the optimum heat‐treatment parameters (requires 3 to 4 months)p p ( q )
• Conduct additional heat‐treatment experiments and perform final round of mechanical testing, metallography and fractography (requires 2 months)
P j i d b l d i 9 h• Project is expected to be completed in 9 months.
• Estimated charges total $20,000