VECALLOY 752 has been specifically designed to perform in ag-gressive environments where impact, abrasive wear, and ero-sive wsear are factors. VECALLOY 752 is an iron-based alloy which grows extremely hard, near spherical, tungsten boride particles throughout the entire weld bead thickness. In terms of wear resistance, the high density of tungsten boride particles enable performance on a level similar to WC-Ni overlays at a

lower price point. Further, the small scale of a tungsten boride particles provides enhanced impact resistance, 4-30X that of conventional hardfacing products, including WC-based, CCO (chrome carbide overlays), and nanostructure forming steels.

DESIGN APPROACH

The design process for VECALLOY 752 involves a proprietary high throughput computational metallurgical process to evalu-ate millions of candidates alloy compositions. Potential candidates are evaluated using advanced screening processes al-lowing for thorough and rapid development of materials.

VECALLOY 752

Technical Datasheet

PRODUCT OVERVIEW

VECALLOY 752 PERFORMANCE

Overlay Properties

Hardness 66-70 HRC

ASTM G65A: 0.06-0.08 grams lost (low stress abrasion

Coefficient of Friction <0.09

(ASTM G77 in Mineral Oil)

Impact Resistance: >6,000 20J Impacts

to Failure

Hard Boride/Carbide Fraction: >50%

10073 Commerce Park Drive. Cincinnati, OH 45246 / Phone: 513-847-3586 / Fax: 513-847-2880

E-Mail: sales@polymet.us

Vecalloy 752 at

1,000X

~2600HV Complex Tungsten Boride Particles, Harder than

Tungsten Carbide

VECALLOY 752 FORMS A MICROSTRUCTURE SIMILAR TO WC/Ni BUT AT A FINER SCALE

VECALLOY 752 is the first hardfacing alloy which pairs the toughness required for high impact applications while competing with the most wear resistant coatings available. VECALLOY 752 forms a microstructure which looks similar to WC/Ni PTA, W-based hard particles immersed in a matrix. It is the only hardfacing alloy which possesses this type of microstructure while simultane-ously avoiding the long needle-like particles known to cause problematic embrittlement in chromium carbide overlays and many nanostructured steel alloys.

VECALLOY 752

Technical Datasheet

752

WHY VECALLOY 752 OUTPERFORMS WC-NI PTA

2. Fine-Scale Microstructure: WC PTA coatings typically use carbide particles on the order of 50 to 200 microns in size. Notice how large carbides can be seen in the WC PTA micrograph, but at 500X the hard-phases in 752 are very small. Unlike typical WC PTA applications, the carbides and borides in VECALLOY 752 are thermodynamically grown in the liquid alloy and thus are always consistent in size, shape, and distribution. This fine scale microstruc-ture has many beneficial effects such as preventing small sand particles from attacking the matrix directly, and distributing thermal stresses more evenly upon cooling. However, perhaps the most important benefit of the 752 microstructure is the ability to withstand impact and high stresses. Almost every application which is commonly understood to be an abrasive environment is also an environment containing high stress and significant levels of impact.

Carbide

Crack

WC PTA at

25X

Carbide Depleted

WC PTA at

500 X

VECALLOY 752 at 500 X

1. Homogeneity: Unlike a PTA coating which effectively involves depositing two separate materials simultaneously, a Ni matrix and WC particles, VECALLOY 752 is deposited as a single alloy which naturally grows a network of carbide and boride fine-scale precipitates. Whereas WC may sink or float in a molten weld pool resulting in a varied perfor-mance through the thickness of the weld, the VECALLOY 752 carbide and boride network are thermodynamically driv-en to precipitate at equal concentrations throughout the weld thickness. Notice in the micrographs below how the WC particles are clumped together in some areas of the weld and some sections are free of WC particles in the WC-Ni PTA coating. Whereas, the carbide spacing is thermodynamically driven to a very precise spacing in the VECALLOY 752 weld.

WHY VECALLOY 752 OUTPERFORMS WC-NI PTA AND CHROMIUM CARBIDE

Many people are surprised to see that despite VECALLOY 752’s nearly equal wear resistance compared to WC PTA coatings, VECALLOY 752 significantly outlasts WC PTA in actual application. The answer lies in the revolutionary improvement in im-pact resistance. Notice large cracks (highlighted by white arrows) running through the microstructure of the 25X WC PTA coating. While WC PTA is well known as the standard for abrasion resistance under ASTM G65 testing, relatively low levels of impact can generate cracks and significant levels of material loss. As shown in the diagram below, when subjected to repeat-ed 20J impacts, VECALLOY 752 lasts 4x as long as the most impact resistant chrome carbide and 30X as long as WC/Ni PTA. How can we define the level of impact that one should pay attention to? This particular impact test is standardized to 20J of impact energy, - the amount of energy developed by dropping a 2kg rock a distance of 1m. It stands to reason that many more applications should consider the use of coating solutions with better impact resistance.

VECALLOY 752 COST, PROCESS, AND PRODUCTIVITY ADVANTAGES VECALLOY 752 deliver WC/Ni PTA performance with the cost and productivity advantages of iron based alloys and MIG (GMAW) welding.

The material properties of VECALLOY 752 allow for unique advantages in cost and productivity that expand the use of extremely abrasion resistant materials into wider markets .VECALLOY 752 is an iron based alloy resulting in significant material cost savings compared to WC-Ni products. Further, MIG welded VECALLOY 752 has a ~99% deposit efficiency while WC/Ni PTA has a 70% de-posit efficiency. This means that 1.4kg of WC/Ni must be purchased for every 1kg deposited. VECALLOY 752, because it is iron based, has a lower density than WC/Ni this results in further cost savings. Consider the manufac-turing of a 12” X 12” (300mm X 300mm) wear plate with a 1/4” (6mm) overlay. In production this plate would require half the amount of material by weight when using VECALLOY 752 as opposed to WC PTA. This immediately results in significant cost sav-ings, in addition to significantly reducing the weight of the component. Unlike WC/Ni, which is typically deposited using PTA because MIG results in a non-uniform structure and poor performance, VE-CALLOY 752 has no loss in performance when MIG welded. This allows MIG equipment and processes to be used instead of PTA. MIG equipment avoids the frequent powder clogging of PTA process and is cheaper to purchase, maintain, and run. In addition to direct material cost, VECALLOY 752 can be deposited with far higher productivity than WC/Ni PTA. For example, WC/Ni PTA is typically deposited at a rate of 11 in2/hr. VECALLOY 752 is typically deposited at a rate of 40 in3/hr, almost 4 times as fast!

VECALLOY 752

Technical Datasheet

SUGGESTED APPLICATIONS

VECALLOY 752 coatings are suggested for use in any application where wear resistance is required. The revolutionary im-provement in impact resistance and toughness will typically result in an extended lifetime over WC PTA and Chromium Car-bide coatings. Specific applications include: Shaker Screens Grade Blades and other Ground Engaging Tools Chute Blocks Pipe I.D. Wear Plate Mill Liners Slurry Pipe Shovel Wear Packages Other Mining Applications

HOW TO USE VECALLOY 752

VECALLOY 752 is currently available in 1/16” metal cored wire. Additional welding diameters are available upon request. The suggested welding parameters and expected results are provided based on the following pages. For application specific guidance on proper welding procedures please contact: sales@polymet.us

Wire Diameter 1/16 in (1.6 mm)

Current DCEP

Desired Weld Thickness 6—8 mm

Voltage 28—30

Amperage 250—280

Shielding Gas Ar 100%, Ar 98%/O2 2%

Stickout 1 in (25 mm)

Preheat 300—400 F (150—200C)

Torch Drag Angle 5 - 15°

Travel Speed 3—5 in/min

Expected Hardness 65—70 HRC

Expected ASTM G65 mass loss 0.06—0.08 g

VECALLOY 752 1/16 INCH GMAW WELDING PARAMETERS

VECALLOY 752

Technical Datasheet