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As fabricators gain experience welding SCS we hear good news about improved weld quality, savings on consumables and, of course, a decrease in hazardous welding fumes versus welding P&O (August SCS UPDATE). However, we sometimes learn of a new user having problems with excess weld spatter when welding SCS. Studies show that small changes in shielding gas and filler wire feed eliminate excess spatter and yield greater savings on consumables. This article gives the basis of the SCS advantages and explains welding practices that let fabricators enjoy those advantages while avoiding the excess spatter.

Big Advantages to Welding SCS Upcoming SCS Events SCS Coil Line and SCS Sheet         Line - Why We'll Use Both

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Consistently Stronger Welds In 2003, ten similar samples of welded SCS and hot roll P&O sheets were tested to failure in shear at St. Louis Testing Laboratories. It took an average 580 pounds higher shear load to cause failure in welded SCS samples than the HRPO samples (Figure 1). In all cases, failure of the SCS samples was not at the weld, but in the base steel itself. All HRPO samples failed at the weld nugget. The SCS advantage comes from higher weld integrity. A certain amount of the weld arc’s energy goes to burning the oil on HRPO sheets. This introduces even more contaminants to a HRPO surface that is already fairly ‘dirty’ compared to SCS. The net result is to reduce the integrity of HRPO welds compared to SCS welds. User experience gained since the 2003 tests reinforces this finding. That Matter of Excess Spatter Most fabricators who switched to SCS reported cleaner, stronger welds with really no spatter. Figure 2 shows a typical such SCS weld sample. However, a few reported unacceptable levels of spatter. To find the cause, TMW enlisted the help of the Illinois Manufacturing Extension Center which provides technical services to manufacturers. IMEC’s project manager, Steve Bosworth, teamed up with Optimum Engineering Solutions, Inc. to conduct controlled welding tests of SCS. First, they replicated the welding practices of fabricators who reported excess spatter and saw similarly unacceptable results They next studied changes in shielding gas composition and filler wire feed rate (click for details). Changing from 90%Argon-10%CO2 to 95%Argon-5%Oxygen improved arc stability and drastically reduced spatter. Lowering wire feed speed worked very well with the new gas recipe. In fact, using ER70S-6 filler wire at a slower feed speed with the Argon-Oxygen mix provided notably better penetration and improved bead appearance when welding at the same speed.

Greater Savings on Consumables The study revealed that the best parameters for welding SCS (or P&O for that matter) were different from what these fabricators had been using. A change to the optimized shielding gas/filler wire combination not only ensures superior SCS welding performance, it also yields savings on consumables! The gas supplier for the study sells the new Argon-Oxygen mix at 5% less than the Argon-CO2 mix. But bigger savings are realized on filler wire. The more uniform weld bead you get with optimized SCS parameters means less filler material for a given weld joint. Couple that with a reduced wire feed rate for the same welding speed, and the savings in welding wire can reach 30%. We’ll gladly send SCS samples for you to do your own welding tests, plus the shear strength and spatter test reports. And we've developed guidelines for optimized GTAW welding of SCS. IMEC’s Bosworth explains that the guidelines reinforce methods that the AWS, ESAB and others prescribe, so welders should use, them in general, not just for SCS. Call TMW to obtain your copy prior to welding SCS for the first time.

November 9 - Cincinnati, OH This unique seminar includes industry experts and a tour of a state-of-the-art slitting line. An SCS technology lecture is featured. Click to register

TMW recently unveiled its revised web site -   www.thematwks.com The site fully explains our capabilities, services and the reasons why The Material Works has quickly become one of the top toll processors in the Midwest.

Since we announced our joint venture with Heidtman Steel to operate the first SCS Coil Line for producing SCS in coil form (August SCS UPDATE) we’ve been asked if we’ll keep running our SCS line for sheets (photo at left) after the Coil Line line is operational. The answer is YES! While SCS processing of coils represents greater volume than processing sheets, the marriage of the Stretcher-Leveler and SCS Sheet Line for sheets offers important advantages: Advantage 1: Thicker Material The first SCS Coil Line will process material up to 0.250” thick and 72” wide (later models can be scaled up to at least 0.375" thick). Meanwhile, our SCS Sheet Line runs twice that thickness - up to 0.500”. That extra capacity is key to serving certain of our customers.

Advantage 2: Panel-Flat Sheets Stretched sheets are ‘panel-flat’ and free of all residual stress. Some fabricated products need this flatness to avoid springback when shearing or lasering, and you can’t get it from roller leveling. Stretcher-leveling sheets, then SCS brushing them afterwards, is the best way to produce this superior product for demanding fabricators. What about reversing the process? Why not use the SCS Coil Line to clean coils first, then run the coils on a cut-to-length line with a Stretcher-Leveler? It would work fine. We know since we’ve stretched SCS sheets at TMW. But reversing the process introduces a potential problem: it would cost more to keep the SCS sheets as ‘white-glove clean’ as customers require . . . Advantage 3: Keeping It Clean Coils coming off the SCS Coil Line will be dry (no oil) and perfectly clean. You need the material to stay that way when it’s subsequently processed into blanks. That means your cut-to-length lines had better be clean too. They usually are not. Say you run coil after coil of P&O and hot roll black. To then run clean SCS coils on the same lines, you’ll need to do a full line clean up or the blanks won’t come out clean. The big expense is not labor to clean the line; it’s revenue lost from downtime. Dedicating a clean cut-to-length line to just SCS coils could make sense with high volume, but SCS cleaning of sheets after blanking and stretching makes sense from the outset . Advantage 4: Keeping It Affordable One notable reason it makes sense is economics. The SCS Sheet Line costs $1.25 million less than the SCS Coil Line. That means companies who market sheets, rather than coils, can start their SCS operation on a smaller capital outlay. There are other situations where the SCS Sheet Line might make more sense than the SCS Coil Line, but we touched on the key ones here. To learn more about the opportunities and economics of bringing SCS benefits to your customers, in the form of SCS sheets, please contact us at The Material Works.