Technical Data
CrC 60 wearplate is a high chromium carbide alloy (AWRA 2360) deposited onto high grade ductile mild steel plate (AS1594-A1006).
Overview
Chemical composition of hard overlay material is similar to high chromium white cast irons that are known to be be one of the most cost effective range of alloys available to combat wear. However, unique fabrication of deposited alloys are considered superior to cast alloys as the rapid cooling rate produces a very fine microstructure.
This consists of primary and eutectic chromium carbides (1200hv-1750hv) and an acicular morphology in an austenitic matrix which is tough and of medium hardness.
Brittle deposit is fully fused to ductile backing plate, ensuring optimum wear resistance combined with strength and toughness. This enables a flatter surface finish between weld runs and greater consistency in chemical composition deposited compared to other techniques. The result is a more uniform metallurgical structure and wear resistant product.
Stress Cracks
CrC 60 wearplate may forms cracks and these are also not uncommon in chromium white iron deposits.
These are stress relieving cracks that do not spread past the alloy base plate interface and are relatively fine, short and infrequent. In most applications these are quickly filled with fine particles and do not present any adverse affect to wear resistance.
Comparisons
Click on Show more for available data on some typical wear resistance comparisons
Mild steel |
1.0 |
Quench & tempered steel BRINEL80 |
5.0 |
Quench & tempered steel BRINEL360 |
6.5 |
Quench & tempered steel BRINEL500 |
9.0 |
NIHARD 1 |
16.5 |
CrC 60 |
18.0 |
Tungsten |
22.0 |
Rating and Testing
Wear resistence rating is done in strictly controlled testing environments performed by certified approved experts of the National Association of Testing Authorites Australia – NATA.
Results, such as those shown above produced in comparative tests, includes analysis for abrasion as well as impact under both high and low stress conditions.
Depending on the specific purpose and test targets, there is potential for a range of variables. Fluctuation across variables is likely to be intensified if conducted as a ‘field operations’ exercise outside of a controlled testing environment.
Variables to be considered in results analysis may include:
- different testing procedures
- high or low stress abrasion
- differences in applied loads
- speed variations
- different or deliberately abnormal calibrations
- material type
- impact loads
- flow speeds, consistencies/inconsistencies
- support structures used
- particle size and shape
Chemical analysis
Typical analysis of CrC 60 wearplate includes data on primary properties as well as trace elements and other alloy mixture additives
Chromium |
29.0%
|
to
|
31.0%
|
Carbon |
4.3%
|
to
|
5.1%
|
Manganese |
1.5%
|
to
|
2.1%
|
silicon |
0.8%
|
to
|
1.2%
|
Trace elements
- molybdenum
- nickel
- sulphur
- phosphorous
Alloy additives for custom grade wearplate to meet specific wear resistant requirements such as high heat, fine particle dust abrasion, increased hardness and impact resistance (plus many more) may include:
- vanadium
- boron
- nickel
- molybdenum
- niobium
Hardness
CrC 60 wearplate hardness range is 59 to 62 on the ROCKWELL C harness scale – 650 BRINEL | 820 Vickers.
A typical undiluted harness is 60 ROCKWELL C
Variances in hardness are dependent on
- where reading is taken – near hard facing layer surface | centre | near interface with mild steel base plate
- the thickness of hard facing overlay deposit
- quality / analysis of raw materials used
Hardness in isolation is not a true indication of alloy wear resistance. It should only be used as a guideline to assess quality and effectiveness of the wearplate. While hardness can be increased by adding other alloys to the hard facing mixture, many other factors also need to be considered that may impact outcomes:
- deposition method
- carbide structure achieved
- industry use
- material application for the wearplate
CrC 60 wearplate attachments
There are 3 common methods to attach CrC 60 wearplate
- nelson studs
- countersunk insert
- plug weld
Cutting
Plasma arc is the preferred method but we do sometimes use other methods. Often cutting is where production starts on the factory floor so getting it right is imperative.
Wherever possible all cutting is done from the mild steel side. This helps reduce risks associated with contamination of the mild steel base with carbon and chromium which can potentially cause brittle welds.
Arc air and friction disc are also effective cutting methods that we may use if and when it is required or more practical to do so for certain projects.
Any mistakes made in this early phase of production can set a negative tone for the entire job.
Luckily our Technical Lead ensures this doesn’t happen. Overseeing all cutting operations, he ensures dry run as part of our pre-production best practice. He is highly experienced and nothing short of a genius in all things cutting as one of our wearplate specialists across design, programming, plant operation and maintenance.
Cold Forming
CrC 60 can be bent and we may use different methods. This is dependent on individual job requirements and whether the wearplate surface will be an ‘inie’ or an ‘outie’
inside facing wear surface
- press bake or rolling to a diameter of 600mm
- smaller diameters – minimum 200mm – with recommendation that 4mm on 8mm or 8mm on 10mm only be used
outside facing wear surface
- minimum of 1 metre diameter is recommended
- forming to be done at right angles to weld runs
Welding
Welding is absolutely crucial to production of quality wearplate so our best practice and criteria is strict and stringent.
Our qualified Senior Tradesman is incredible at what he does and a true wearplate specialist in CrC 60. With over 20 years experience he oversees tight quality controlled welding operations to ensure:
- wearplate and matting metal surfaces are clean, and flat
- correct clamp and track position
- low carbon steel substrate of CrC 60 wearplate can be welded using normal consumables for MMAW and GMAW for mild steel
- no structural welding on the wear surface as it has negligible yield strength
- weld preparation includes no dilution transfer from a structural weld into hard facing that may result in cracking of the weld