Document Type
Thesis
Date of Award
6-30-1957
Degree Name
Master of Science in Chemical Engineering - (M.S.)
Department
Chemical Engineering
First Advisor
C. L. Mantell
Second Advisor
George C. Keeffe
Third Advisor
Saul I. Kreps
Abstract
The corrosion resistance of the chromium-manganese-nickel austenitic stainless steels has been established through a study of the available literature and unpublished data obtained from producers and users of these alloys. Several compositions are available as listed below. DESIGNATIONCOMPOSITION % CMnCrNiNAISI 2010.155.5/7.516.0/18.03.5/5.50.25AISI 2020.157.5/10.017.0/19.04.0/6.00.25CM0.1513.0/18.014.0/17.01.00.25Tenelon0.1014.517-0.40TRC0.0816.515.0 min.1.00.2CMN0.651225-0.452040.087.5/10.017.0/19.04.0/6.00.25
The AISI Type 201 and 202 alloys have been listed by the American Iron and Steel Institute.
The development and application of these alloys was necessary because of the increasing shortage of nickel and the wide use of the chromium-nickel austenitic stainless steels. The chromium-nickel steels are used in a wide variety of consumer items and are necessary for defense equipment. In tines of national emergency the government restricts the use of nickel for consumer applications. The manganese substituted alloys are intended to fill the conusmer shortage.
It has been found that the addition of manganese to the alloy will, not seriously affect the corrosion resistance. In most environments, manganese less than 10% has no effect, if the chromium and nickel remain constant. Above 10%, manganese decreases the corrosion resistance. This effect, however, is slight up to 18% manganese, the highest content reported.
More significant is the effect of lowering the nickel content. Reduction of nickel, particularly below 4%, will greatly reduce the corrosion resistance. It is the lowering of the nickel content rather than the addition of manganese that accounts for any reduction in corrosion resistance with the chromium-manganese-nickel austenitic stainless steels, since the chromium content is unchanged.
These alloys are subject to intergranular corrosion awing to the precipitation of chromium carbide as in the chromium-nickel alloys. They can not be stabilized with columbium or titanium. These elements will remove both carbon and nitrogen from the alloy with the formation of delta ferrite. It has been shown that by reducing carbon it is possible to prevent intergranular corrosion. The carbon limit has not been clearly established. It is reported to be either 0.025 or 0.060% depending upon the investigator.
The AISI Types 201 and 202 alloys appear to resist attack by a number of Chemicals. Their resistance is similar to that of the Types 301 and 302 alloys. In a number of environments the resistance is better than Types 304 .and 316 alloys. The oxidation resistance of the Types 201 and 202 alloys is equivalent to Type 304 up to about 1500?F. Above 1500?F the rate increases appreciably. These alloys are as susceptible to intergranular attack as the corresponding chromium-nickel alloys. The atmospheric corrosion resistance is good.
The alloys designated as 204 and 204L have a lower carbon content and should offer some improvement in corrosion resistance over the Types 201 and 202 but little data are available. The lower carbon content should make them less susceptible to intergranular attack.
The very low nickels high manganese-chromium alloys have a corrosion resistance similar to that of the Type 430 alloys. They are resistant to only mild corrosives and would be used where the physical and mechanical properties are superior to the Type 430 alloy. The atmospheric corrosion resistance is good by both exposure tests and long time service tests. The alloy shows no promise for high temperature service where resistance to oxidation or sulfur is required.
A table of expected corrosion rates for the chromium-manganese-nickel and chromium-manganese alloys in a number of environments is presented. A complete to bibliography of English language literature on the corrosion resistance of these alloys is included.
Recommended Citation
Merrick, Robert Dewitt, "Corrosion resistance of the chromium-manganese-nickel and chromium-manganese austenitic stainless steels" (1957). Theses. 2554.
https://digitalcommons.njit.edu/theses/2554
