Properties

CHEMICAL COMPOSITION
Cromanite contains a nominal 19% chromium,  10% manganese and 0.5% nitrogen.  The steel has received a European standard EN 10 088 listing designated as type 1.3820.

MECHANICAL PROPERTIES
In the annealed condition, cromanite has a typical yield strength of 550 MPa, a tensile strength of 850 MPa and an elongation of 50%.  The hardness level is typically 250 HB which increases to a level of approximately 500 HB under impact conditions.  It has an impact toughness of about 250 J.

CORROSION RESISTANCE
The resistance of cromanite to reducing acids is similar to that of the ferritic stainless grade AISI 430, while its pitting resistance (in chloride solutions) is similar to that of the austenitic Stainless Steel grade AISI 304.

Like AISI 304, cromanite is susceptible to chloride cracking, but it is largely resistant to hydrogen embrittlement.  In addition, sensitization after welding does not occur.

CORROSION WEAR RESISTANCE
Cromanite has been specifically designed to have a combination of high strength, toughness and ductility with a high work hardening rate. Cromanite will work harden under impact conditions to a level of 500 HB.  This work hardening behaviour is similar to Hadfields manganese steel.

However, unlike Hadfields manganese steel, cromanite is a Stainless Steel with excellent weldability and thus it can also be easily fabricated.

Cromanite performs exceptionally well in high impact wear environments, especially where the environments are corrosive.

A high impact environment will ensure that cromanite will work harden, resulting in the steel being able to absorb large amounts of energy before wear occurs.

CUTTING
Cromanite, like other Stainless Steels, cannot be cut with a conventional oxy-acetylene torch due to the high chromium content.

Plasma cutting and profiling of cromanite is the fastest and most economical thermal cutting method available and thicknesses of up to 50 mm can be cut successfully.

Laser cutting and profiling of cromanite can be done up to a thickness of 10mm.

Cromanite can be sheared successfully.  It has a shear strength 50% higher than the 300 series Stainless Steels.  This should be taken into account when determining the maximum shearing capacity on any particular shear.

WELDING
Good results have been obtained using filler metals such as Stainless Steel types 309 and 307 and duplex types such as 2507/P100, 22/09 and CN 23/12Mo - A, welded by the MMA (SMAW or stick welding) method.

The welding of cromanite to itself is quite straightforward using the manufacturers recommended parameters.

Due to the higher thermal conductivity of cromanite versus the resistively of the electrodes,  these electrodes must be run at the higher end of the recommended amperage range and if necessary even higher.

Care should be taken to avoid damage to electrode coatings due to overheating.  Distortion effects are similar to the 300 series Stainless Steels and care must be taken to reduce or eliminate this.

When welding cromanite to 3CR12 with the MMA process, electrodes such as types 307 and 309 should be used.  When welding cromanite to mild steel, type 309 electrodes with their higher chromium content are preferred, thus reducing dilution effects.

The higher end of the amperage range should be used to avoid lack of fusion type defects.  Distortion effects are similar to the 300 series Stainless Steels and care must also be taken to reduce or eliminate this.

When selecting a filler material for welding cromanite, it is important that application be considered.  This is due to the fact that the strength of the weld metal may not match that of the parent metal.

MACHINING
When machining cromanite, heavier feeds and slower speeds should be used to reduce tool build up and minimise work hardening.  Fabricators with experience in machining Stainless Steels have not encountered problems with the machining of cromanite plate.

Cromanite showed no significant differences in machinability compared to 316L stainless steel in various trials.  If difficulty is experienced with machining, then Ti nitrided tools should be used.  

Applications

Cromanite is an excellent candidate for materials handling applications involving wet sliding abrasion and wet high impact abrasive wear.  This is because it has an excellent combination of strength and toughness, has the work hardening ability of Hadfields manganese steel, and the added advantage of good corrosion resistance.

In addition, cromanite has great potential for variety of high strength applications due to its excellent strength both at room temperature and at elevated temperatures.

Uncoated materials exposed to corrosive environments can form a protective corrosion film on the surface.  Abrasion removes this surface film and damages the newly exposed bare metal, which is left vulnerable to further corrosive attack.  In such cases, materials with poor corrosion resistance, such as carbon steels, have an unacceptable wear rate.  

Technical Data
 
CHEMICAL COMPOSITION  

All values given are for 20^oC unless otherwise specified.  

TYPICAL PHYSICAL PROPERTIES  

MECHANICAL PROPERTIES 
 

Mechanical properties at room temperature (20^oC)

TYPICAL MECHANICAL PROPERTIES AT ELEVATED TEMPERATURES  

Short time elevated temperature tensile strength.