Specifications include, but are not limited to: Material: The cutting edges shall be alloy steels meeting the approval of the Department. The steels shall be melted by the electric-furnace, basic-oxygen or other similar commercially accepted steel making process, and may be either ingot cast or strand cast. The manufacturer shall have the option to fabricate and machine the blades in the as-rolled or annealed condition, and then subsequently quench and temper the steel to meet the requirements of this specification.; Chemical Analysis: A certified analysis of each heat of steel shall be furnished to the Department to verify the weight percentages of the elements specified in Paragraph 2. A product analysis of the cutting edge from an independent laboratory, in lieu of a heat analysis, can be furnished to the Department. The chemical composition shall be within the ranges for the elements specified in Paragraph 2, but can deviate within the permitted variations for the same elements as listed in Table B of ASTM Standard A 6, General Requirements for Rolled Structural Steel Bars, Plates, Shapes and Sheet Piling.; Hardness: The finished cutting edges shall have a Rockwell C Scale (Rc) hardness of not less than 25, nor more than 35. The corresponding Brinell hardness (BHN) range for a 3000 kgf load and a 10 mm ball is 266 to 327 BHN. The Rockwell C or Brinell hardness shall be determined on a finished cutting edge in accordance with ASTM A 370 Standard Test Methods and Definitions for Mechanical Testing of Steel Products.; Impact Toughness: All cutting edges shall have a minimum average Charpy V-notch impact toughness of 25 ft-lbs at 32°F, based on a minimum of three test specimens. No single test value out of three or more specimens shall be less than 17 ft-lbs. Testing shall be in conformance with ASTM A 370. The Charpy V-notch test will not be required for blades that have a lifetime guarantee providing replacement for blades that are broken by impact.; Dimensions: The cutting edges shall conform to the Department’s Code Numbers as shown on the drawings, or they shall fit the plow as identified by the manufacturer’s name and model if the Code Number is not shown. For Code Number drawings, contact the Bureau of Materials & Physical Research, Engineer of Tests at 217 782-7200. Allowable tolerances for dimensions and holes shall in accordance with standard commercial practice. All snowplow blades shall be square edge flat unless otherwise specified.
