Vol 1 Issue 7

1. Welcome and Thanks
2. Internet Services
3. Wear Technology - Wear Plates ( AR and Overlay )
4. Heat Input

1. Welcome and Thanks

Just want to welcome all the new arrivals to “Wear It’s AT”. The size of the list is becoming very impressive. We are building a great community. By the way, if anyone would like to address the community on a subject, just let me know and I can easily arrange it. Please keep in mind that this is a private list and I protect all email recipients very carefully. I don’t allow any spamming or junk stuff…… Just good wear related content.

2. Internet Services

At the request of many of my contacts, clients, and “Wear It’s At” subscribers, I am building a Directory addition to my Web Site. This will carry listings of hardfacing manufacturers, wear related products, end users, shops, vendors, and consultants. I will also be designing and hosting Web Pages for those who don’t have a Web Site. These pages will become an integral part of the Clad Technologies Web Site. It’s a great way for those who want to enjoy the fruits of my growing Web Site traffic. .For those who already have Web Sites, active links will be part of the subscription. Clad Technologies has become one of the top search engine finds for “Hardfacing and Wear Technology”. My traffic is growing tremendously with each day. I would like to share this success with you. As this project develops, I will keep you posted. Please let me know if you or your friends would be interested in such a service.

3. Wear Technology - Wear Plates ( AR and Overlay )

For those who are not familiar with Wear Plates, allow me to elaborate just a little. Wear plates are plates or sheets of material that are used as sacrificial elements to prevent the excessive wear of expensive components. They can also be used as stand alone components in applications such as hoppers, chutes and guides. They vary in thickness ranging from 0.25” to 2” thick; widths from 48” to 96” and lengths up to 288” long. Chemistries can range from 2% to well over 40% and are usually iron based materials. Wear Plates can be broken down into two categories: Abrasion Resistant (AR) and Overlay Plates. AR plates are generally low alloy and low carbon to allow for ease of welding and fabrication. They range in hardnesses from 300 BHN to 500 BHN and are remarkably formable. The hardness comes from the formation of martensite and not by carbide content as with plates. Prices range from .50 to 1.50 per lb. AR plates are generally used where there is a moderate abrasion problem. For more severe abrasion applications, plates are the chosen products. There are a number of manufacturers here in North America:

Many of these alloys are very good quality and offer a range of impact and abrasion resistance.

AR plates are easily welded and require very little preheat and interpass temperatures, except in thick sections where the mass of metal causes a large heat sink. In many cases, mild steel electrodes such as 7018 are suitable for welding. Nickel bearing low alloy rods such as 8018Ni2 offer greater impact properties over 7018, but neither will approach the abrasion resistance of the plate. It is therefore necessary to consider capping welds in high wear areas with a 400 or 500 BHN hardfacing rod.

Overlay Plates are not through hardening plates like the AR Plates, but are composites instead. The composite is made of mild steel base plate and a welded of high chromium iron weld deposit, also know as chromium carbide. The thickness ranges from 1/8” to ˝” typically, and the mild steel base plate thickness ranges from Ľ” to 2” thick. The mild steel base plate allows for the attachment of the plates to existing structures such as chutes, buckets, etc. The chromium carbide affords the maximum in abrasion resistance. In the G65 Abrasion Test, plates will rank from 10 to 15 times greater than AR plates. In the field however, where there are other wear factors that must be taken into account, the ranking shrinks to about 3 to 8 over AR plate. This is still a good buy, although plates are generally 3 to 5 more expensive than AR plates. Overlay plates costs are sometimes easily justified by the savings realized in downtime and not the cost of the plate. There are more than a dozen manufacturers of plate in North America.

Surprisingly, plates have pretty good ductility. It’s safe to say that they can be formed to a radius roughly 20 times their thickness, although this can vary depending upon the method of manufacture. Welding also is surprisingly straight forward, since the backing of the chromium carbide is mild steel. 7018 type electrodes and wires can be used easily, but for those applications where there is a danger of contaminating the weld with the high carbon , 309 and 312 stainless steel electrodes should be considered.

A history or plates can be found on my web site, at http://www.cladtechnologies.com/Articles/Minetec/mintec.htm and methods of plate manufacture at http://www.cladtechnologies.com/Articles/CrCarbide/article.htm . You can also observe applications at http://www.cladtechnologies.com/Product%20Pages/Wearplate.htm .

3. Heat Input

I Had an interesting question the other day and one that I know many of you have. It concerns Heat Input. What is the best welding technique to reduce Heat Input?. Let me first address what Heat Input is, and why we want it to be low. Heat Input can be considered as the amount of heat pumped into the weldment or . We want it low because it keeps the components cool and less susceptible to distortion and reduces penetration and dilution. Heat Input is a function of Amps Volts and Travel Speed. For those who like equations, it’s quite simple: Amps x Volts divided by Travel Speed. Think about the size of the numbers involved and you will quickly arrive at the fact that Amps has the most influence. That’s because we generally change this number by large quantities. I.e. from 300 to 350 Amps. Volts and Travel Speed also have an effect, but to a lesser extent. Having said that, it does not mean that Volts and Travel Speed should be ignored. Quite the contrary. Travel Speed has a tremendous effect because it is so closely related to Bead Width. Stringer beads have no weave and therefore produce low Heat Inputs. Weaving the bead has quite the opposite affect. Think of Travel Speed as being the actual forward progress of the welding process. Since the bead is being weaved, the actual forward progress of the arc is quite slow, producing a very low Travel Speed number. Don’t forge that we divide by the Travel Speed in the Heat Input equation. So the smaller the number, the greater the Heat Input. So, it all boils down to the fact that if you want to keep down the Heat Input, you must use Stringer beads with as little Amps and Volts possible.