August 2023 Volume 5

MATERIALS

Tool and Die Repair Alloys – “Composite, Don’t Compromise” By David Lee

Old tools with new requirements. The forge tooling horizon looks pretty much the same today as it has for at least the last 85 or so years and the goal remains the same, that is, keep the per – part – cost for tooling as low as possible. There are a limited number of options to accomplish that goal and welding is the only option that can, in itself, present so many choices. The forging die steels in service today are required to be tough and ductile to absorb the abuse that the forging process hands out, while at the same time being hard and unyielding to provide satisfactory productivity. These requirements, when coupled with a complex cavity design, less than optimal forging conditions or forging materials that just don’t like to move can mean even the superior alloys used in the forge tooling we know today are a compromise. There are several options available to the forge to improve the productivity of the tooling, and all of them involve modifying the surface condition of the cavity but none of them can significantly alter the base material used in the impression. The benefits of a surface “treated” tool vary with the process used but none of them permit the ability to “restore” treatment intermittently during a production run. There is only one process that allows that to happen and that is welding. Starting in 1945, Weld Mold began developing welding alloys that would perform better than the die steel being used and procedures for the successful application of those alloys. Since the beginning the goal has been to maximize, to the degree possible, the number of parts an impression can produce per sink before the cavity is too worn to economically repair it. The goal had two elements that were to be satisfied: • Develop improved welding alloys that had better wear characteristics. • Invent application methods that would reduce the time it took to do weld repairs. By 1952 both requirements had been met, flood welding was born. At the end of the first quarter of the 21st century, forging is still a major industry worldwide, even as the process becomes more automated, and the materials being forged take new and interesting forms. Welding and welded tooling are still the most economical solution to improve cavity performance and die life. Just as new technology is being adapted to fit the forging process, advances in welding automation technology have been and continue to be developed. There are a number of welding alloys that can be counted on to provide improved wear characteristics as well as methods that can be used to ensure economical application of the alloys.

Regardless of what method is used, welding has been proven to significantly enhance the productivity of forge tooling, depending on the alloy and procedure used. This enhancement not only extends to producing more parts per resink but just the ability to weld the impression will keep the die in service, potentially forever. The alloys used for forging die repair today, most of which have been around for decades, are vastly different than those used up into the 1950’s and later in some instances. The mainstream alloys, the Weld Mold 500 series are as old as flood welding itself and still find a large market for die repair because they just work. Moderately priced and readily available, Weld Mold 525, 535, 540 and 545, NiCrMoV alloys, have been the standards for forging die repair since the ‘50’s and have been so successful that they have been copied and marketed around the world by other manufacturers. Available as coated electrode, and cored wire for a variety of application methods, these products have changed forging die repair potential forever. With a chemistry that is closely related to the base metals they are most commonly used on; the 500 series has a proven track record of out-performing the base metals in parts produced. • Weld Mold 525 is a low carbon nickel chrome moly weld filler suitable for weld repair on the shanks of hammer dies and for use on press dies anywhere outside the impression as well as forging component repair of sow blocks, rams, columns and bases, press frames die sets and rams on presses. With an as welded hardness of 25 – 30 Rc, 525 can be used as a high strength fabrication weld filler as well. • Weld Mold 535 is also low carbon but with richer alloying and higher physical characteristics that are suitable for use in forging die cavities for the press and hammer process and can provide better productivity and die life than even the die steels themselves. • Weld Mold 540 produces an as welded hardness of 38 – 42 Rc. With higher physical properties and tougher machinability than the 535, it is recommended that carbide inserted tooling be used. Weld Mold 540 has also been used as a critical fabrication material in the oil drilling industry. • Weld Mold 545 has significantly higher carbon than the other 500 series alloys and develops an as welded hardness of 40 – 45 Rc with an almost flat tempering curve that will require inserted tooling or EDM. As the acceptance of welded tooling became more commonplace and the demand for even greater improvements in forging die production increased, Weld Mold worked to meet these expectations by developing alloys that have become the Gold Standard for material

FIA MAGAZINE | AUGUST 2023 28