Specifications include, but are not limited to: 2.1 Steel. The blades shall be fabricated from flat hot rolled carbon steel meeting the requirements of either ASTM A576 or ASTM A575 with the range of Grades SAE 1020 or equal. 2.2 Tungsten Carbide Inserts. The inserts shall be a high shock WC Grade of tungsten carbide. 2.2.1 The inserts shall meet Virgin Tungsten Carbide quality specifications and shall meet the following requirements. 2.2.1.1 Face Insert Characteristics (for dual underbody carbide tipped snowplow blades only): Specification Requirement Cobalt Content, percent 19.0 – 21.0 Density, g/cm3 (ASTM B 311) 13.25 - 13.65 Hardness (ASTM B 294, Rockwell A Scale) 83.5 - 85.0 Transverse Rupture Strength, psi, min. 330,000 2.2.1.2 Single or Center Insert Characteristics (for both single carbide tipped and dual underbody carbide tipped snowplow blades): Specification Requirement Cobalt Content, percent 10.5 – 12.5 Density, g/cm3 (ASTM B 311) 14.1 - 14.6 Hardness (ASTM B 294, Rockwell A Scale) 87.5 – 90.5 Transverse Rupture Strength, psi, min. 350,000 2.2.2 The face insert shall be rectangular and the single or center insert shall be trapezoid design with the following dimensions for each: 2.2.2.1 Face Insert Dimensions: Specification Requirement Height, inch 0.745 ± 0.005 Width, inch 0.310 ± 0.005 Length, inch 2.000 ± 0.005 2.2.2.2 Single or Center Insert Dimensions: Specification Requirement Height, inch, long side 0.75 ± 0.01 Width, inch 0.365 ± 0.01 Length, inch 1.000 Nominal Bottom Angle 25 degrees with a nose radius of 1/16-inch for Trapezoid 3/16-inch nose radius for Bullnose 2.3 Finished Blades. 2.3.1 Insert Placement. A 3/8” groove for the single carbide inserts will be milled in the center of the blade edge. The groove for the dual underbody carbide inserts shall be milled on the blade edge. For the dual underbody, the tungsten carbide inserts shall be positioned in the milled area with approximately 0.010-inch space between the inserts the entire length of each cutting-edge section. Each of the inserts shall be one inch in length for the center inserts and two-inch in length for the face inserts. It may be necessary for some of the inserts to be different than the nominal lengths to make up for the spacing between the inserts. The number of one-inch inserts shall be no less than one or more than three from the number required for one insert per inch of blade length. The number of two-inch inserts shall be no less than one or more than two from the number required for one insert per two inches of blade length. 2.3.2 Brazing. The inserts shall be brazed on all contact surfaces consistent with sound brazing practice with no evidence of voids or use of shims. Brazing shall be of such strength and quality as required to prevent movement or loss of the inserts during use. 2.3.3 Physical Requirements. All blades shall be straight and free from flaws and injurious defects and shall have workmanlike finish. 2.3.3.1 The finished blade sections shall be free of warpage and longitudinal deviation shall not exceed 1/8 inch in a four-foot or five-foot long blade section or 3/32 inch in a three-foot long blade section. The edge that rests upon the pavement shall be straight and true. The longitudinal warp and the alignment of this edge shall be measured by extending a straight edge from one end of the blade to the other and measuring from the straight edge to the blade at the mid-point of length. 2.3.3.2 The difference between the highest and lowest tip point shall not exceed 1/32 inch on any given blade assembly. 2.3.3.3 Punching shall be 11/16 inch square holes with 5/8 inch diameter countersink 3/8 inch deep to receive either 5/8 inch or 3/4 inch diameter plow bolts as required. Location of holes shall be in accordance with AASHTO standards for “heavy-duty” punching. Details, location, and spacing of the holes shall be as shown on the attached drawing for a standard state highway three-, four- or five-foot blade. 2.3.3.4 Moldboards are punched with holes 1/8 inch larger than the blade bolts. Accordingly, blade punching will be of such accuracy, both for the spacing between holes and for the spacing between the end hole and the end of the blade, that the blades will fit the moldboards, thus making the blade sections interchangeable. 2.3.3.5 The number of single or center carbide inserts for 3 foot blades shall be between 34 and 39, the number of single or center carbide inserts for a 4 foot blade shall be between 45 and 53. 2.3.4 The paint used to coat the blades shall be dry prior to shipment and shall not smear or track during handling.
