ASTM F568M is an ASTM International

ASTM International

ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...

 standard for metric

Metric system

The metric system is an international decimalised system of measurement. France was first to adopt a metric system, in 1799, and a metric system is now the official system of measurement, used in almost every country in the world...

 bolts, screw

Screw

A screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread, often in the form of a nut or an object that has the...

s and studs

Threaded rod

A threaded rod, also known as a stud, is a relatively long rod that is threaded on both ends; the thread may extend along the complete length of the rod. They are designed to be used in tension...

 that are used in general engineering applications. It is officially titled: Standard Specification for Carbon and Alloy Steel Externally Threaded Metric Fasteners. It defines mechanical properties for fasteners that range from M1.6 to 100 in diameter.

This standard defines property classes, the metric equivalent of a screw grade, that are almost identical to those defined by ISO 898-1, except for the addition of the 8.8.3 and 10.9.3 standards. These two additional standards are fasteners that have the same mechanical properties as their base property class (i.e. 8.8 and 10.9), but are made from weathering steel.

This is a standard set by the standards organization ASTM International

ASTM International

ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...

, a voluntary standards development organizations that sets technical standards for materials, products, systems, and services.

Mechanical properties

Head markings and mechanical properties

Head marking	Grade, material & condition	Nominal size range [mm]	Proof strength [MPa]	Yield strength (min) [MPa]	Tensile strength (min) [MPa]	Core hardness [Rockwell]
	Class 4.6 Low or medium carbon steel	5–100	225	240	400	B67–95
	Class 4.8 Low or medium carbon steel; fully or partially annealed	1.6–16	310	340	420	B71–95
	Class 5.8 Low or medium carbon steel; cold worked	5–24	380	420	520	B82–95
	Class 8.8 Medium carbon steel; quench and tempered	Under 16 (inc.)	580	640	800
		17–72	600	660	830	C23–34
	Class 8.8 low carbon Low carbon boron steel; quench and tempered
	Class 8.8.3 Atmospheric corrosion resistant steel; quench and tempered
	Class 9.8 Medium carbon steel; quench and tempered	1.6–16	650	720	900	C27–36
	Class 9.8 low carbon Low carbon boron steel; quench and tempered
	Class 10.9 Alloy steel; quench and tempered	5–100	830	940	1040	C33–39
	Class 10.9 low carbon Low carbon boron steel; quench and tempered
	Class 10.9.3 Atmospheric corrosion resistant steel; quench and tempered
	Class 12.9 Alloy steel; quench and tempered	1.6–100	970	1100	1220	C38–44