Stainless Steel Grade Markings

Steel and stainless steel fasteners such as screws bolts and studs are like many manufacturing tools governed by an official grading system developed by the international organization for standardization iso.

Stainless steel grade markings.

The s stands for stainless and the 30400 is the marking for stainless steel and those markings that you re seeing on these bolts are standard to ifi recommendations which are standardized throughout the industry. Head markings metric bolt class mechanical properties proof load mpa min yield mpa min tensile strength mpa class 8 8 medium carbon steel quenched and tempered 580 600 640 660 800 830 class 10 9 alloy steel quenched and tempered 830 940 1040 class 12 9 alloy steel quenched and tempered 970 1100 1220 a2 stainless also called 18 8 or. 18 10 stainless often corresponds to this. 18 8 316 stainless steel alloy with chromium and nickel.

Tensile strength is the amount of pull the bolt can withstand before breaking. All sizes thru 1 n a. The method used for tightening the bolt is also dependent upon the grade of the bolt. In screws bolts and studs these standards refer to thread grade markings or the standard measurements for thread sizes and dimensions.

Ss316 is often used for building nuclear reprocessing plants. After 304 stainless steel it is the second most widely used steel mainly used in food industry and surgical equipment. Specification for alloy steel and stainless steel bolting materials for high temperature service. It belongs to the general model which is 18 8 stainless steel.

Grade or manufacturer s identification symbols shall be applied to one end of studs 3 8 in diameter and larger ands to the heads of bolts 1 4 in diameter and larger. Gb grade is 0cr18ni9. Grade a325 carbon or alloy steel with or without boron. 1 2 thru 1 1 2 85 000.

It has better temperature resistance than 304 stainless steel. 1 4 thru 1 1 2 120 000. Also known as marine grade stainless steel due to its increased resistance to chloride corrosion compared to type 304. Most watches that are made of stainless steel are made of this grade.

Grade 8 medium carbon alloy steel quenched and tempered. The nut manufacturer at his option may add other markings to indicate the use of atmospheric corrosion resistant steel. Astm a194 a194m carbon and alloy steel nuts for bolts for high pressure and high temperature service. Rolex is an exception in that they use type 904l.

Bolts are made of different grades of steel.