Solidification and solid-state transformation mechanisms in Si alloyed high-chromium white cast irons

Journal Article · Thu Apr 01 00:00:00 EST 1993 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

DOI:https://doi.org/10.1007/BF02656520· OSTI ID:6519655

Laird, G II ^[1]; Powell, G L.F. ^[2]

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1. Bureau of Mines, Albany, OR (United States)
2. Commonwealth Scientific Research Organization, Woodville (Australia)

Chromium white cast irons are widely used in environments where severe abrasion resistance is a dominant requirement. To improve the wear resistance of these commercially important irons, the US Bureau of Mines and CSIRO Australia are studying their solidification and solid-state transformation kinetics. A ternary Fe-Cr-C iron with 17.8 wt pct (pct) Cr and 3.0 pct C was compared with commercially available irons of similar Cr and C contents with Si contents between 1.6 and 2.2 pct. The irons were solidified and cooled at rates of 0.03 and 0.17 K/s to 873 K. Differential thermal analysis (DTA) showed that Si depresses the eutectic reaction temperature and suggests that it has no effect upon the volume of eutectic carbides formed during solidification. Microprobe analysis revealed that austenite dendrites within the Si alloyed irons cooled at 0.03 and 0.17 K/s had C and Cr contents that were lower than those of dendrites within the ternary alloy cooled at the same cooling rate and a Si alloyed iron that was water quenched from the eutectic temperature. These lower values were shown by image analysis to be the result of both solid-state growth (coarsening) of the eutectic carbides and some secondary carbide formation. Hardness measurements in the as-cast condition and after soaking in liquid nitrogen suggest an increase in the martensite start temperature as the Si content was increased. It is concluded that Si's effect on increasing the size and volume fraction of eutectic carbides and increasing the matrix hardness should lead to improved wear resistance over regular high-chromium white cast irons.

• OSTI ID: 6519655
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Vol. 24A:4; ISSN 0360-2133
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CAST IRON
SOLIDIFICATION
WEAR RESISTANCE
ABRASION
CARBIDES
CARBON
CHROMIUM ALLOYS
DIFFERENTIAL THERMAL ANALYSIS
ELECTRON MICROPROBE ANALYSIS
HARDNESS
PHASE TRANSFORMATIONS
SILICON ALLOYS
ALLOYS
CARBON COMPOUNDS
CHEMICAL ANALYSIS
ELEMENTS
IRON ALLOYS
IRON BASE ALLOYS
IRON CARBIDES
IRON COMPOUNDS
MECHANICAL PROPERTIES
MICROANALYSIS
NONDESTRUCTIVE ANALYSIS
NONMETALS
THERMAL ANALYSIS
TRANSITION ELEMENT COMPOUNDS
360102* - Metals & Alloys- Structure & Phase Studies