ARE YOU USING MANGANESE STEEL IN CORRECT APPLICATIONS?
Manganese is one of the most misunderstood and confusing steels used in wear-resistant steel applications. Manganese is used extensively in the mining, aggregate (rock crushing), foundries, metal recycling, and railroad industries.
Recycling, mining, and aggregate applications utilize Manganese in the same type of machinery for similar functions in crushing applications. Whether you are shredding junk car bodies or smashing large rocks into smaller-sized rocks for specific applications; much of the equipment you use is the same.
Manganese cone crushers are used in mining and aggregate industries to crush rocks and encounter tremendous wear. Overlaying a new Manganese cone with JADCO Crusher Guard is shown in this photo. This application will extend wear life 30-50% more than unprotected components.
Manganese Steel Properties
Manganese steel stands up to constant impact longer than any other known material, yet has the ability to develop some abrasive wear resistance. It will resist impact significantly longer than high carbon steel or cast iron.
Naturally, it will wear, but as the work-hardened surface is worn away; the metal beneath becomes work hardened from the continual pounding impact.
The key to Manganese steel’s effectiveness is beneath the work-hardened layer, the steel core remains ductile. When Manganese is exposed to impact, high-stress scraping, gouging, or pounding; Manganese can last up to 10 times longer than mild steel.
Not Recommended for Abrasion
When abrasion from sand or other fine materials wears the surface without impact, the Manganese steel wear resistance is not greater than mild steel. It is also less abrasive resistant than high carbon steel which has been heat treated.
A perfect example of using Manganese steel incorrectly was in a coal crusher feeding a coal fired boiler. When their equipment was first installed they were crushing Eastern Coal, which is very hard. Manganese is perfect for smashing hard materials, allowing the swing hammers and screen to work harden under the constant impact. The hammers would last 6 months before changing.
The company found they could save fuel costs buying Powder River Basin Coal from Wyoming, rather than the Eastern Coal. PRB coal however is very soft. The change to softer coal, meant the Manganese swing hammers never had a chance to work harden. You can imagine their surprise when the same hammers that were lasting 6 months with Eastern Coal, were totally worn out in 3 weeks using PRB coal.
Don’t Treat The Symptom, Look for the Cause
After initially thinking they received poor quality hammers, investigation into what happened revealed the change in coal was the cause of the dramatic difference in wear. By switching to an alloy steel hammer with a higher initial Rockwell hardness in place of the Manganese steel; their hammer life again returned to normal.
Manganese Steel Properties
The most common Manganese is known as Hadfield Manganese, invented by Sir Robert Hadfield in 1882. Hadfield Manganese steel typically has a direct 10 to 1 ratio of Manganese to Carbon. The standard range for Hadfield Manganese contains 11% to 14% Manganese, and 1.1% to 1.4% Carbon. This ratio is critical for increasing the strength and hardness in Manganese steels.
As cast, Manganese is relatively soft, registering 187 BHN or 10 Rc. Cold working applications such as impact by repeated hammering increases both the hardness and the strength of the Manganese castings.
Surface hardness from impact can reach a maximum of 550 BHN or 55 Rc. The depth of the hardness will depend on the richness of Manganese steel chemistry and the frequency and pressure of the applied impact stresses. The lower the percentage of Manganese and Carbon, the lower the hardness scores you will achieve.
Yield strength of Manganese steel is about 66,000 PSI and ultimate tensile strength is about 107,000 PSI. Elongation is 35% in 2 inches.
Identification of Manganese Steel
In the field Manganese is identified with a magnet. As produced, Manganese is not magnetic or attracted by a magnet. After being used for a period of time, the impact wear areas will have a slight magnetic pull.
The non-impact areas, the sides or back of the casting remain non-magnetic. It is the work hardening that makes the impacted surface slightly magnetic. This is the only known metal to have this magnetic change.
Heat Effects on Manganese Steel
Manganese is usually found as a casting; or formed into bar stock, plate or angle shapes. Manganese steel is expensive to machine, which is why most parts are cast to shape and finished by grinding. As cast, Manganese steel that has not been heat-treated, is very brittle because of the Manganese carbides.
Standard toughening treatment at the foundries, consists of slowly heating the steel to 1850° and quenching it in water. This heat treatment gives Manganese steel it’s high strength and toughness.
NOTE: If any later fabrication process raises the temperature above 500°F, the toughening treatment MUST be repeated.
Sustained temperatures of 500°F to 800°F may cause the Manganese to become brittle. While carbon steels gain strength from tempering, Manganese steel loses ductility when tempered. Most people don’t know it can become brittle and prone to cracking in application when overheated.
How Can My Cone Crusher Application Slow Down The Abrasion Wear?
When new manganese components are installed on crushers, they have not had a
chance to work-harden to their full potential. However, the abrasion starts immediately when the first rock hit it.
An industry first, CRUSHER GUARD provides an initial protective barrier on new manganese castings for crusher bowls and mantle applications.
Using CRUSHER GUARD You Benefit By:
- Allows Manganese to work harden to maximize crusher performance
- Reduces number of costly change-outs per year
- Less inventory needed
- Decreases downtime and lost production
CRUSHER GUARD is just one example of how listening to our customer’s needs created a product your industry needs.
For over the last 42 years JADCO has focused exclusively on delivering consistent, longer equipment life for our customers.
Now you understand why we are able to deliver better results to our customers. We think differently by strictly focusing to improve your current results.
Allow us to help you today by calling (724) 452-5252, or email info@jadcomfg.com.
We will schedule a meeting with one of our local wear plate specialists at a time that best fits your schedule.
Remember, the only thing you have to lose by not working with JADCO, are your profits.
When your standard wear plate gives out, be certain to give JADCO a shout! (724) 452-5252
