RA% is a term that stands for “reduction of area percentage.” It is an important requirement of the ASTM F1554 specification, in addition to other specifications. This value is reported as a percentage of the original test piece. When fasteners undergo mechanical testing, they are pulled to failure and the diameter of the point at which the fastener breaks is measured and compared to the original diameter. The difference between the original sample and the broken piece is calculated and reported as the reduction of area percentage.
Each grade of ASTM F1554 has a minimum requirement to meet. For example, grade 36 has a 40% minimum reduction of area requirement which means that in order for the bolt to comply to this specification it must reduce in diameter at least 40% (or more) before breaking.
curious about this. we have a MTR for B7 all thread, and it has reduction of area and has the chemical requirements. can you call it grade-105 or do we need an engineer to stamp it?
@Greg- If the B7 meets all the chemical and mechanical requirements of F1554g105, you can call it G105. The standard marking requirement is only red paint on the exposed end unless supplemental requirements S2 and/or S3 are invoked in which case the manufacturer must stamp the rod with their registered manufacturer’s mark and the grade.
Greetings!!!
We have produced grade 8.8 bolts with 10B35 raw material dia 20 mm, all parameters are ok and no issues are there is compliance but RA is observed as 42% – 44%, please guide us with remedial measures on how we can achieve 52%
@Rakesh- Apologies, but we are unable to offer assistance with this, You might consider contacting a metallurgist.