You’ll get the most out of this guide if you need to learn chromium carbide overlay plate (AKA wear plate) is exceeded only by your willingness to execute and make a purchase.
How do you determine where to purchase chromium carbide overlay from? How do you tell which overlay plate provides you the best wear life to get your equipment back up, quickly? Here are a few factors you need to consider when purchasing or researching chromium carbide overlay plate.
Combine this information with some practice and you are well on your way to becoming a savvy CCO plate expert.
Now, let’s explore each of them in details.
1. The overlay plate has surfacing layers. How about flatness?
Based on industrial standard, the flatness of the overlying plate shall be control within ±3mm/m. so you may ask how to make sure of the wear plate flatness.
Then how to test the exact flatness of chromium carbide plate?First of all, the steel plate should place on the flat ground. It is simple to use a steel ruler with the ruler standing on the steel plate. Measure the maximum distance between the lower end of the ruler and the steel plate, corresponding to the shape of the steel plate.Second, there are special tools for higher accuracy. Measuring straightness by using a very rigid rectangular section ruler with a measuring scale similar to a depth gauge.Third, a laser shaper for automatic measurement is a more advanced test method.
All three principles are the same, but that the speed and accuracy are different. You can check overlay plates by your tools at hand.
2. Can CCO plates have welding cracks?
Answer is yes. overlay plates, welding cracks shall be evenly spaced, and the cracks shall be fine.
The production process of a wear-resistant composite plate is made by metallurgical surfacing, either open arc welding or submerged arc welding. Welding current is generally 500 ~ 700A, and the temperature of the welding arc reaches 6000 ~ 7000 ℃.
The instantaneous high heat causes the welding wire and the base plate to reach the melting point to form a molten pool (so-called bead), and the alloy powder added to the molten pool is melted to form a surfacing layer.
In the cooling process after thermal deformation, to release the welding stress existing in the surfacing composite steel plate, many cracks of different sizes will be generated in the direction of the surfacing layer perpendicular to the bead.
This crack is the result of stress release. Therefore, if there are no cracks or few cracks on the surface of the overlay plate, it is an unqualified product! These cracks seem to be very easy to worry about. They are afraid that the wear-resistant composite steel plate will spread into the base plate during use, and even they are scared of breaking or falling off. This worry about cracks is unnecessary.
Production belongs to metallurgical combination and has excellent bonding performance. The blow does not fall off or break during use. As long as the crack intervals are uniform and the cracks are small, there is no problem.
3. How to test and make sure of the surfacing layer size?
It is best to use UT for testing. UT thickness measurement is possible. The echo from the interface between the two materials is visible due to the slight velocity difference between carbon steel and stainless steel cladding. However, repetition is minimal. Do not use a thickness gauge with a digital display. UT instrument with A-Scan presentation is necessary.
If UT is not available, can measure after grinding, the surfacing layer shall be visible, flat and no unevenness, and the average thickness is measured at multiple points
4. How to judge an overlay plate with surface painting?
We all know the saying, “don’t judge a book by its paint.” Ironically the same goes for CCO plate. One area of concern is the cracks that appear. The surface of the plate will exhibit numerous hairline cracks, which are a natural stress-relieving phenomenon that is essential to the performance of the plate. It enabled the plate to be formed, bent, and rolled without damage. These operations are maybe necessary for your replacement parts.
Sometimes plates are entirely painted. It may make the plate appear aesthetically pleasing, but this is a tactic to cover imperfections or inconsistencies in the welds. Proceed with caution when dealing with companies that provide fully painted plates. The exception would be when the customer specifications require this step.
5. Can overlay plates have welding defects?
The quality defects of the wear overlay welding are common. When the relevant technical personnel inspects the welds of the chromium carbide overlay plate, they should find the defects early and limit the welding defects to a specific range to ensure the safety, economy, and stability of the unit. Run. The following is an analysis of these defects.
The most common occurrence of chromium carbide plates during welding is hydrogen pores, which are divided into internal pores, surface pores, and joint pores. The leading causes of pores are: the edge of the bevel is not clean, there are moisture, oil stains and rust, the electrode or flux has not been baked according to regulations, the core is destroyed, or the coating has deteriorated or peeled off. Due to the existence of pores, the useful cross-section of the weld is reduced. Excessive pores will reduce the strength of the weld and damage the compactness of the weld metal.
The depression left at the edge of the weld is called an undercut. The cause of undercut is due to excessive welding current, fast bar speed, too long arc, or improper angle of the electrode (wire). Undercuts reduce the working section of the base metal joint, which causes stress concentration at the undercuts, scattered in important structures or dynamic load structures. Undercuts are generally not allowed, or the depth of undercuts is limited.
Slag inclusion is the slag remaining in the weld. Slag inclusion also reduces the strength and compactness of the weld. The leading causes of slag inclusion are a. Residual slag left by aerobic cutting or carbon arc gouging at the edge of the weld; b. Bevel angle or welding current is too small or welding speed is too fast; c. “Dross” is formed because the flow is too low, or the rod is improperly moved. D. When alkaline electrodes are used, the slag will be caused by the arc is too long or the polarity is incorrect.
Not welded or fused
When welding the chromium carbide plates, the root of the joint is not completely melted. It is called non-penetration; there is local non-penetration in the weldment and weld metal or weld layer. It is called the unfused. Therefore, no essential structural parts are allowed to be incompletely welded or unfused.
6. How about overlay plate cutting edges?
Cutting edges shall be all around: linear, no burrs; it is best to use a large plasma cutter.
A precision cut surface has the following characteristics:
Square face (less than 3-degree bevel)
Smooth, with nearly vertical draglines
Little to no nitrides or oxides
Little to no dross, and what dross is present should be easy to remove
Minimal heat-affected zone and recast layer
7. How about the total thickness of the wear plate?
The answer for this question is the thickness shall be controlled within the allowable range, ± 0.5㎜;
8. How about the hardness of overlay plates?
Hardness shall be within the required range.
Due to the problem of the oxide layer and surface flatness on the surface of the wear-resistant steel plate, when testing the wear-resistant plate, it is best to mill off 1.0-2.5mm on the surface of the steel plate, and then perform hardness inspection on this surface. Generally, we recommend that you mill off 2.0mm for hardness inspection. The testing tool is preferably a desktop hardness tester (the data monitored by the portable hardness tester can only be used as a reference).
The general hardness is HRC55-62;
9. What is a suitable alloy composition?
If possible, measure and check alloy composition.
Not all applications are the same; it sounds like a simple thought. If requests are different, then shouldn’t the solution need to be changed? Consider looking for a company that offers multiple chemistries. If you have an extreme abrasion application, then you need a CCO plate that is tailored to meet the harsher abrasion and wear. For abrasion challenges that include impact elements, you need a solution that can handle the beating and not destroy the plate. Look for a company that can work with your needs, provides you a solution that addresses your specific application.
10. How about allowable metallographic?
If possible, do metallographic analysis. The volume fraction of Cr7C3 carbides in the metallurgical structure can reach more than 50%.
In the extension of chemistry, the most significant characteristic of the alloy overlay is its microstructure. Hence, when checked out under a microscope, the carbides will take the form of white substance against a dark background, that that’s the matrix.
A perfect microstructure, for more excellent abrasion resistance, must have a dense array of needle-like carbides that, in cross-segment, look as slender hexagons with a small hole in the middle.
Moreover, whenever you notice an appearance of uneven shaped spots or avenues of white. Such as either ladder, fish-bone patterns, or central poles with rungs on any of the sides. This is a sure sign that the carbon content is beneath optimum for high abrasion resistance, but it has also improved impact-resistant properties.
11. Which kind of supplier is trustworthy to buy wear plates?
The wear plate suppliers are different, and the products and production processes are different market position. The main is to look at the history of the supplier and the customer lists from suppler; the second, to see its scope of supply; the third, to see the boss, whether he is honest and reliable. Generally, the long-established manufacturer has a well-known reputation in the market and is always under the attention and supervision of people. The chromium carbide plates produced by him have reasonable quality assurance.
12. The test sample plate is a must before purchasing
Look at the material of its products. The selected wear plate must have a higher wear resistance. The wear plate must replace the machine to withstand severe wear during use. It must have excellent processing properties so that we can use it at any time, replace it with the wear-resistant parts we need.
It is best to check the sample. Through the test sample plate, we can conduct in-depth understanding and testing of the product, know how the product is processed, and know what characteristics the product has when it is used. Therefore, you need to look at the model before purchasing and using the wear plate to choose a product that you think is better and more suitable so that you can be assured when using it.
When it comes to purchasing the CCO plate, make sure to look deeper into the aspects of the plate and manufacturer providing it. Your down equipment needs to be repaired and stay operational for your site to make a profit. You do not want to throw your money away by compromising production time; you need to ensure the CCO plate you are proceeding with is the global standard in overlay plate.
Getting excited yet? If you get confused, don’t give up; we have folks who can help you with purchase of chromium carbide overlay plate. Contact us now!