Yield Strength is the maximum load at which a material exhibits a specific permanent deformation. Proof Load is the axial tensile load that the product must withstand without any evidence of permanent set. Grade A325 - Carbon or alloy steel with or without Boronġ8-8 Stainless - Steel alloy with 17-19% Chromium and 8-13% NickelĬlass 8.8 - Medium carbon steel, quenched and temperedĬlass 10.9 - Alloy steel, quenched and temperedĬlass 12.9 - Alloy steel, quenched and temperedĪ-2 Stainless - Steel alloy with 17-19% Chromium and 8-13% Nickel Grade 8 - Medium carbon alloy steel, quenched and tempered Grade 5 - Medium carbon steel, quenched and tempered Maybe this article only applies to thin or hard types of wood.
Without predrilling, the wood squeezes the screw for a better grip. The below diagram shows examples of English and Metric bolt and nut markings. I am a novice, but it seems like predrilling in home construction, with 2×4’s and 1×2’s is unnecessary and will actually weaken the screw’s holding power. Some metric nuts also have the strength class number stamped on their face. Metric bolts are a bit more straight forward, usually having their strength class number stamped right on the bolt head. A grade 8 bolt will have 6 radial lines on its head. So, for example, a grade 5 bolt will only have 3 radial lines on its head. The number of lines on the bolt head is 2 less than the actual grade. English bolts have radial lines on their head to identify the grade, or strength class. The higher the grade, the stronger the bolt. or S.A.E) are categorized by grade, from grade 2 to grade 8, where the grade represents inch strength. You can usually figure out the grade, or strength, of a bolt by looking at the markings on its head.