MANGANAL STEEL - The Wear-Resistant High Manganese Steel Answers to two dozen common questions
STULZ-SICKLES STEEL COMPANY Since 1916 - Stulz-Sickles Steel Company, producers of Manganal, has prepared this question and answer booklet in response to many requests.
We feel this information will be an aid to those involved in maintenance-repair of many types of equipment. It is noteworthy that Manganal is a time-tested, proven product and to this day remains the toughest steel commercially available.
Manganal is high manganese, austenitic (non-magnetic), work-hardening steel. Typically, its chemical composition is:
Manganese - 12.00/14.00%
Carbon - 1.00/1.25%
Manganal thrives on severe wear conditions. The more impact and hammering it receives, the harder the surface becomes. This characteristic, known as work-hardening, plus the fact that it remains ductile underneath, makes it a most effective steel in combating impact and abrasion.
It was discovered by Robert A. Hadfield in Sheffield, England in 1882, and was first produced in the U.S. in 1892.
It has very high strength, ductility, toughness, and excellent wear resistance in the most punishing applications.
It is available under the trade name Manganal as plates, hot-rolled bars and special shapes.
With carburized or case-hardened steel, the depth of hardness is fixed. When Manganal is subjected to wear the hard surface continuously renews itself.
Depending on deformation of the surface crystalline structure, it can work-harden up to more than 500 Brinell. When originally put into service it is about 200 Brinell.
No. It has a low coefficient of friction which is very important to wear resistance. This is particularly obvious in metal-to-metal applications.
One example of surface work-hardening under almost pure impact is the liners of shot-blast cabinets. Manganal work-hardens rapidly, takes a smooth polish due to its low friction property, yet retains its great toughness under the hardened surface. Generally, the heat-treated alloy and steels, although of high hardness, tend to erode comparatively fast, and break down on the surface. The use of high-manganese steel castings in certain railroad trackage is another example of impact with very little abrasion.
Here again it surface work-hardens, takes a mirror-like finish, and retains its original underneath toughness. An example is wear strips under conveyor chains. The compressive abrasion of metal-to-metal contact deforms the surface structure of manganal and therefore, work-hardens it rapidly. The polish that it develops and its low coefficient of friction not only reduces the wear on the conveyor chain, but usually results in reduced power requirements for operating the equipment, because of reduced friction.
The same qualities mentioned in 9 and 10 are developed. An example is quarry rock crushers. The high impact and grinding abrasion destroys most other steels rapidly. Manganal withstands the punishing abuse, without breaking or quickly eroding. Other typical uses are shovel buckets, teeth and loaders working in earth and stone where there is a general mixture of impact/compressive abrasion.
Not so well. It may outwear mild steel a bit in sand or cinders but usually there is not enough surface deformation of Manganal steel to work-harden if very much. However, an exception would be sand or grit between moving steel parts, such as gears, conveyors, tractor rollers, etc. Here, the grit particles under pressure deform the surface of Managal steel so the work-hardening and polishing takes place.
No better than ordinary steels. It rusts and is attacked by acids to about the same extent.
It is non-magnetic substantially. It is used for its nonmagnetic property in electrical transformer assemblies and for industrial lifting magnets.
Continuous high temperature can embrittle it.
The AWS EFeMn grouping and the specially modified 12/14% manganese electrodes produced by several electrode manufacturers, such as Stulz Manganese XL Welding Electrodes. They are used for high tensile welds and surfacing to resist abrasion.
It has little effect on Manganal from a practical operational standpoint. A rough rule of thumb would be to not allow any local area to remain at visible red-heat for more than 2 or 3 minutes (1100-1200F approx.) at a time. In the electric welding process, localized heat is dissipated fairly rapidly into the air and the bulk of the weldment. In the case of high build up with many layers of weld passes the welder may either skip weld or weld intermittently to reduce localized heat.
It has no effect on strength or ductility. Practically all electrode manufacturers alloy the EFeMn group with nickel, molybdenum, or other alloys which do away with any danger of embrittlement in the weld itself.
Assuming reasonably good welding procedures the all-weld metal tensile strength of AWS EfeMn electrode is about 125,000 psi. In addition, the weld metal has high ductility. When tested to destruction, welds seldom break, but rather pull out the parent metal.
Generally, no. Under almost all circumstances there is no advantage over the electric arc. Oxy-acetylene can result in too high heat input into the high-manganese steel parent metal.
It does not lend itself to machining by usual machine shop methods. When a drill or cutting tool is applied it quickly work-hardens the area to the extent that machining becomes very difficult. It is, however, machined within limits, using special methods and tooling.
It can be flame cut by oxy-acetylene torch, cut by abrasive cut-off machine and electric welded. Shearing, bending and rolling require heavy equipment which has at least twice the capacity that would be needed for the same thickness of mild steel.
Not from any practical standpoint. Alloy and carbon steels are hardened by heating and quenching. High-manganese steel under this treatment becomes ductile and tough.
Only by work-hardening. Refer to question and answer #2.