Friday, June 22, 2012

What is Grade 8.8 stainless steel fasteners

A grade 8.8 fastener can be manufactured from any material whose mechanical properties meet or exceed the requirements set forth in the relevant harmonised standards.
The two-digit nomenclature is not used to describe individual steel grades and only applies to metric fasteners defined under ISO 965 (as well as derived standards)
The designation system is based on two numbers e.g 8.8 . The first number is the tensile strength of the bolt material (N/mm2 )/100. The second number is = 1/100.(the ratio of the Proof (or Yield ) stress and the Tensile strength expressed as a percentage = 100.[Yield (Proof stress) /Tensile strength] /100
meaning that a grade 8.8 bolt has a nominal ultimate tensile strength (UTS) of 800N/mm2 (or Mpa) and a nominal yield strength of 640N/mm2 (or Mpa).
These values are not expressed in Kg/mm2 or PSI as the first is an expression of mass by surface-area, the second is an expression of weight by surface-area and neither are true units under the SI system.
Lastly, the actual steel grade used by manufacturers may vary but in most cases, a grade 8.8 fastener (self-colour, black-oxide or zinc plated) will be manufactured from a medium-alloy medium carbon steel, typically with 0.30 - 0.50 % Carbon and alloyed with other elements such as Molybdenum, Vanadium, Manganese and sometimes Boron or Cobalt in small quantities. These alloying elements provide the required mechanical properties to reach the minimum strength set forth by the harmonised standards.

Bare in mind that people sometimes refer to "high-tensile bolts" which are typically grade 8.8 or superior under the metric fastener system. Grade 8.8 and superior bolts should always have their grade permanently marked on the head to differentiate them from "low-tensile bolts" as inadvertantly replacing the former with the latter could have disastrous effects.
Grade 4.6 bolts are typically refered to as "low tensile" and are often used in the construction industry as these bolts offer higher ductility and resilience compared to "high-tensile" bolts.
Hope this helps.

Compare this to BUMAX 88 series by contacting your local BUMAX stainless steel fastener engineer at www.bufabusa.com  BUMAX is product line of BUFAB Bulten Stainless.

5 comments:

  1. Super Engineers Manufacturer are best Exporters of Nuts, Bolts, Washers, screws, Threaded Roads all over in india. Super Engineers is a worldwide competitor in the era of Fastener Industry.


    High Tensile Fasteners

    ReplyDelete
  2. Pankaj International is committed to developing, manufacturing, delivering and servicing quality products. Our goal is to continuously improve our products and services in order to satisfy the needs of our customers before, during and after sales.

    In each of our product Category our quality is amongst the best in the world. We use the best quality of raw materials that are tested and subjected to stringent standards as per required specifications. Process capability studies & other statistical tools are employed to check all critical parameters during production. Every batch of finished product undergoes strict down the line process control monitoring which guarantees superior quality products. As a result, Pankaj International is synonymous with technology, quality and service.

    Power presses


















    ReplyDelete
  3. Great blog posted here. Precision drawell is one of the leading sfrc company. For more you can contact Precision Drawell.

    ReplyDelete
  4. thanks admin for providing very useful trick for make a wonderful website or blog, here you can find top alerts:
    tools and dies manufacturers in india

    ReplyDelete

  5. Thanks for providing this information was of great help for my needs, Keep posting content related to
    Stainless steel bolts

    ReplyDelete