Blade Bolts

[WeFixIt]

Some information to resolve any dispute on bolt selection !!

 

Stainless steel is an alloy of low carbon steel and chromium for enhanced corrosion characteristics. Stainless steel is highly corrosion resistant for the price and because the anti-corrosive properties are inherent to the metal, it will not lose this resistance if scratched during installation or use.

 

It is a common misconception that stainless steel is stronger than regular steel. In fact, due to the low carbon content, stainless steel cannot be hardened. Therefore when compared with regular steel it is slightly stronger than an un-hardened (grade 2) steel fastener but significantly weaker than hardened steel fasteners.

 

Stainless steel is also much less magnetic than regular steel fasteners though some grades will be slightly magnetic.

18-8 usually no markings refers to any stainless steel containing approximately 18% chromium and 8% nickel. This is the most common stainless designation for hardware. Common types up to 20mm

18-8 Stainless Steel alloy with 17-19% Chromium and 8-13% Nickel

 

 

Metric fasteners

 

Steel alloy marked A-2 with 17- 19% Chromium and 8-13% Nickel

Tensile strength of around 500-700mpa

 

Cllass 8.8 -16mm and below med carbon steel quenched and tempered

Tensile strength of around 800mpa

 

Class 10.9 - 16mm and below alloy steel quenched and tempered

Tensile strength of around 1040mpa

 

Class 12.9

Alloy Steel, Quenched and Tempered

Tensile strength of around 1220mpa

 

Steel is the most common fastener material. Steel fasteners are available plain as well as with various surface treatments such as zinc plating, galvanisation, and chrome plating.

 

Imperial Steel fasteners are commonly available in 4 grades. Many other grades exist but are used far less often. The most common grades are Grade 2, Grade 5, Grade 8, and Alloy Steel. Grade 2, 5, and 8 are usually plated with a silver or yellow zinc

 

Bolts of different grades are marked on the head to show what grade bolt they are.

 

Imperial fasteners

 

Grade 2 is a standard hardware grade steel. This is the most common grade of steel fastener and is the least expensive. Grade 2 bolts have no head marking (sometimes a manufacturer mark is present).

Tensile strength of around 60,000-74,000mpa. (Decreases as size increases)

 

Grade 5 bolts are hardened to increase strength and are the most common bolts found in automotive applications. Grade 5 bolts have 3 evenly spaced radial lines on the head.

Tensile strength of around

120,000-105,000mpaound 60,000-74,000mpa. (Decreases as size increases)

 

Grade 8 bolts have been hardened more than grade 5 bolts. Thus they are stronger and are used in demanding applications such as automotive suspensions. Grade 8 bolts have 6 evenly spaced radial lines on the head.

Tensile strength of around

150,000 mpa

 

Alloy Steel

Alloy steel bolts are made from a high strength steel alloy and are further heat treated. Alloy steel bolts are typically not plated resulting in a dull black finish. Alloy steel bolts are extremely strong but very

brittle.

Tensile strength of around 65,000-100,000mpa

 

 

So DON'T use stainless steel replacement blade bolts !

 

They could be a dangerous hazard which if things went wrong it would be your fault for fitting them !!!!

 

 

 

 

 

Is it a chipper, is it a mower or another broken stump grinder who cares we'll fix it!

Edited September 1, 2014 by WeFixIt

[Gary Prentice]

 

 

 

 

Ever tried drilling stainless compared to mild steel?

 

Strong/weak isn't really the right description... just right/wrong material

 

Drilling SS reveals it's hardness, a different material property. Stainless will shear/snap at lower torques, size for size.