Two types of analyses relating to cast iron solidification were conducted. A theoretical analysis using a computer to predict the cooling versus time relationship throughout the test specimen was performed. Tests were also conducted in a ground-based laboratory to generate a cooling time curve for cast iron. In addition, cast iron was cooled through the solidification period on a KC-135 and an F-104 aircraft while these aircraft were going through a period of low gravity. Future subjects for low gravity tests are enumerated

Graham, J. A.

English

NASA Technical Reports Server

LOW-GRAVITY SOLIDIFICATION OF CAST IRON AND 
SPACE TECHNOLOGY APPLICATIONS 
James A. Graham 
Deere and Company 
Moline, Illinois 61265 
DISCUSSION 
Deere has performed a limited number of tests on the solidification of cast irons in the 
low-gravity environment provided by the KC-1 35’s and the F-l 04 aircraft. The results today are 
very promising, although we have not satisfied our total curiosity about the influence of low- 
gravity on the graphite formation and microstructure of cast irons. 
Deere is the world’s largest manufacturer of farm equipment. A few of our products 
are: tractors, combines, tillage, planting and harvesting equipment. We also manufacture a line 
of industrial equipment, including earthmoving and forestry products. Included in our product 
line are mowers, tractors, and other lawn care equipment. 
Cast irons make up about 25% by weight of our products. We have some of the largest 
foundries in the country outside of those operated by the automotive companies. We produce 
3 grades of iron: gray iron, compact graphite and ductile iron. The table below shows the 
properties of these irons. 
TABLE 1. DEERE CAST IRON PROPERTIES 
IRON 
TYPE 
MIN 
TENSILE 
STRENGTH 
MPA 
MEAN 
HARDNESS 
MPA 
ELASTIC THERMAL 
MODULUS CONDUCTIVITY 
GPA W/M"C 
GRAY 200 2100 100 48 
COMPACT 300 2100 135 43 
DUCTILE 550 2100 175 29 
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https://ntrs.nasa.gov/search.jsp?R=19850002714 2020-03-20T21:13:09+00:00Z
Typical microstructures of these cast irons are shown in Figure 1. 
GRAY IRON COMPACT GRAPHITE IRON 
DUCTILE IRON 
Figure 1. Typical microstructures of cast irons (deep etched, 200X). 
Gray iron has interconnected flakes of graphite much like corn flakes in a box. Around 
the graphite is a matrix of metal. 
Ductile iron has spheroidal graphite formations whereas compact graphite is similar to 
flake, but with rounded edges lowering the stress concentrations due to notches that you find 
in the gray iron. The gray iron, by its nature of the many notches all around the graphite 
flakes, is quite brittle. It exhibits little or no ductility whereas the compact graphite iron has a 
higher strength and exhibits some ductility and the nodular iron with the spheroidal shapes of 
graphite exhibits significant ductility and higher tensile strength. 
Our involvement with NASA started about four years ago through the American 
Institute of Aeronautics and Astronautics program of visits for industrial firms to the NASA 
research centers. On these visits to each of the NASA research centers, we observed many 
things of interest to us. We also had visits by Harry Atkins and others of the Marshall Space 
Flight Center team on materials processing in space and by Nancy Williamson and other per- 
sonnel from Rockwell lntemational who were promoting the utilization of the shuttle. These 
visits revealed some of the possibilities for processing materials in space. 
Shortly before these visits, we were requested by a museum to slice some meteorites. 
These meteorites exhibited graphite formations in basically stainless steel, very similar to the 
graphite formations in ductile iron. If these nodules occurred naturally in space as the meteorite 
cooled, what would be the influence of gravity on the graphite formations in our cast irons? 
This question began the discussions of conducting tests in the low-gravity environment on each 
type of Deere cast iron. 
This was suggested to the people at Marshall Space Flight Center and we began our 
discussions on conducting appropriate experiments. The scientists at Marshall had developed a 
furnace which was deemed appropriate for melting and solidifying small cast iron samples in the 
KC-135 aircraft. The sample, itself, was 8 mm in diameter by 20 mm in length. It was placed 
in the crucible and into the insulated furnace. 
At Deere we performed two types of analysis: (1) A theoretical analysis using the 
computer to predict the cooling versus time throughout the small test specimen. To verify the 
calculations and the test equipment, we conducted, in our research foundry laboratory, tests to 
generate a cooling time curve for the cast iron in the furnace. A typical graph is shown in 
Figure 2. 
bn. 11111111111 
7w. 737. 744. 75,. 758. 75s. 771. 779. 7.5. 793. ,,b. 
XCQlDS AFTEl 13126189 
Figure 2. Cooling curve for low-gravity sample conducted in ground-based laboratory. 
77 
The objective of the test was to be able to cool the cast iron through the solidification 
period while the aircraft was going through a period of low-gravity. The period of low-gravity 
was just barely sufficient in the F-104 aircraft to solidify the iron at low-gravity. However, 
prior to the low-gravity period, we had a period in which the gravity was substantially over l-g. 
The initial flights were conducted on a KC-135 in which we had a period of about 30 
seconds of low-gravity. We then switched our operations to the F-104 where we had a period 
of approximately 55 seconds of low-gravity. With the difficulty in being able to solidify the 
iron at exactly the right time in relationship to the low-gravity, we did see some influences on 
the microstructure. The results today indicate that the primary mode of graphite transport is 
by diffusion. 
When the results of our tests, those by Bethlehem Steel in the same test program as 
ours and the work done by Dr. D. Stefanescu at the University of Alabama in Tuscaloosa with 
a directional solidification furnace, there appears to be considerable promise in continued 
experimentation in the solidification of cast iron at low-gravity. 
We are, of course, concerned about the producibility and the cost of producing cast 
irons. For the sake of perfonance and durability, we must keep the strength level up. If we 
increase the hardness to obtain the strength, the tool-life during machining is low and if we try 
to obtain the increased strength at low hardness we then have poor castability in the foundry. 
Anything that we can do to open this window would be very useful in production. 
Also, increasing the ability to control the process and stay within the allowable window would 
make the production of quality irons easier. 
In studying the results obtained to date, it appears that we have three areas in which 
we can obtain additional information by further tests at low-gravity. These are: 
FUTURE SUBJECTS-FOR- LOW~GRAVITY~~TESTS 
PROCESS MANAGEMENT 
CARBON FLOTATION 
HIGH CARBON IRON PHASE DIAGRAM 
CELL SIZE CONTROL 
DIFFUSION MEASUREMENT LIQUID-SOLID 
QUANTIFY DIFFERENCE CAUSED BY LACK OF CONVECTION 
DESIGN DATA 
TRUE LIQUID THERMAL CONDUCTIVITY 
PROPERTIES OF HIGH CARBON 
NEW MATERIALS 
78 
These possibilities are currently under study and will require ground base tests for com- 
parison purposes and tests to verify the functioning of low-gravity equipment. Low-gravity tests 
are envisioned for the F-104 and KC-135 aircraft, and also there is the possibility that the space 
transportation system will be required to obtain longer time periods for the low-gravity tests. 
The interaction between Deere and NASA has extended over several other different 
subjects. For instance, our machines contain various functional elements as shown below. 
FUNCTIONAL ELEMENTS 
ENGINES MONITORS 
TRANSMISSIONS AIR CONDITIONING 
HYDRAULICS CUTTING 
COOLING SYSTEMS SEPARATION 
CONTROLS CLEANING 
ELECTRONIC STORAGE 
MECHANICAL 
HYDRAULIC 
Many of these functional elements also are present in the equipment designed and used 
by NASA. Our machines are made up of various materials such as: 
MATERIALS 
CARBON STEELS ALUMINUM 
ALLOY STEELS COPPER 
CAST STEELS PLASTICS 
CAST IRONS COMPOSITES 
POWDERED NETAL RUBBER 
PLATING PAINTS 
HARD FACING LUBRICANTS 
Some of the materials are also used in NASA equipment. 
In the Deere visits to NASA research centers, we observed many subjects of common 
interest. One was materials technology. Several areas under materials technology were observed 
at NASA and many of these were discussed in detail between Deere and NASA personnel as 
shown on the following page. 
79 
MATERIALS TECHNOLOGY 
COMPOSITES X X 
CERAMICS X X 
ADVANCED MATERIALS IN DESIGN X X 
ORGANIC COATINGS X 
NON-DESTRUCTIVE TESTING X X 
PHYSICAL METALLURGY X X 
FRACTURE ANALYSIS X X 
ADHESIVES X X 
OBSERVED AT DEERE/NASA 
NASA DISCUSSIONS 
Many types of manufacturing processes are used in producing our products. The table 
below shows which processes were observed at NASA and also the detailed discussions between 
Deere and NASA personnel. 
MATERIALS PROCESSING 
FOUNDRY TECHNOLOGY 
METAL PROCESSING 
C,G, IRON 
HAP, 
DUCTILE IRON 
HEAT TREATING 
HIGH ENERGY PROCESSES 
GRAY IRON 
WELDING 
X X 
X 
X X 
X 
X X 
X 
X X 
The pressure is on for increasing the utilization of technology. This is needed for the 
future competitiveness of the companies in this country and to maintain a reasonable level of 
exports to other countries. 
The competition among the companies and countries producing high technology equip 
ment is becoming more intense and we need to continue to upgrade our level of technology to 
maintain our competitive edge. The Third World, by necessity, is having to produce some 
products that formally were produced in this country and in some of the other developed 
80 
countries. The Third World is also struggling to produce their own food with substantial 
opportunity to increase the production of food in a number of countries. 
The number of engineering graduates in this country is substantially less relative to the 
total population than in Japan, thus providing them with increased technological capabilities 
to compete with us even stronger. In the future we will need a higher quality of engineers. 
We must make up for the lack of numbers in the quality and depth of the engineers. We feel 
the use of technology, developed for the space program, should be applied to products that can 
improve the business climate in this country and our competitiveness with other nations. 
There have been substantial benefits to Deere. These include the intellectual insights 
from scientists within NASA who have unique objectives substantially different than the 
objectives of our own in-house scientists. It also provides the means to accelerate the introduc- 
tion of advanced technology. 
NASA has also benetitted from this relationship through the increased interaction with 
scientists in another industry and the realization that the NASA technology can be applied to 
non-aerospace products and processes. However, there are a number of steps that can be take? 
both by NASA and by industry to help in the future. NASA can improve the environment for 
the utilization of technology. NASA, by charter, must cooperate with other nations; however, 
first priorities should be the needs of the industry in this country. Other nations should not be 
helped to gain a competitive advantage over U.S. industry. 
NASA can contribute substantially to the U.S. industrial superiority through the applica- 
tion of the technology they develop. We, in industry, can also take some steps to help ourselves 
and the country. One of these is to take positive steps to find the technology NASA has avail- 
able and apply it to products today. Let’s jointly tell NASA what we need so they can be 
considered in future plans. This will aid us in obtaining more results from our tax dollars that 
go to the very important mission of the NASA organization. 
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Low-gravity solidification of cast iron and space technology applications

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