Standards and grades

Property class 12.9 bolts: maximum strength and precautions

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Property class 12.9 is the highest of the three usual ones: 1200 MPa nominal tensile strength and 1080 MPa yield strength. It is used in heavily loaded joints and in socket head cap screws with an internal hexagon.

It is combined with a class 12 nut. Because of its hardness it is sensitive to hydrogen embrittlement, so electroplated coating requires a controlled process.

Property classTensile strengthYield strengthNut
8.8800 MPa640 MPaClass 8
10.91000 MPa900 MPaClass 10
12.91200 MPa1080 MPaClass 12

Related articles (in Spanish)

Tornillos 8.8, 10.9 y 12.9: qué significan y cuál elegir → Fragilización por hidrógeno en tornillos: el fallo silencioso de la alta resistencia →

Other standards and grades

DIN 933 (ISO 4017) bolt: full thread and property classes → DIN 931 (ISO 4014) bolt: part thread and property classes → DIN 934 (ISO 4032) nut: classes 8, 10 and 12 and sizes → DIN 125 (ISO 7089) plain washer and DIN 9021 wide washer → ISO 4017 (DIN 933): fully threaded bolt dimensions → ISO 4014: bolt dimensions and thread length → DIN 985 prevailing torque nut: sizes and ISO equivalent → DIN 6914 (EN 14399-4) bolt: HV system and dimensions → DIN 975 threaded rod and DIN 976-1 stud → DIN 912 (ISO 4762) socket head screw: sizes and classes → Property class 8.8 bolts: strength, marking and nut → Property class 10.9 bolts: strength, use and class 10 nut →

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