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Zorluk: OrtaBolts, Nuts, and Washers

While replacing a suspension control arm on an imported vehicle, a technician inspects a steel hex-head bolt stamped with the number 10.910.9 on the top of the head. What do these stamped numbers indicate about the fastener?

  1. A
    The bolt is an SAE standard fastener rated at an ultimate strength of Grade 10.
  2. The bolt is a metric fastener belonging to Property Class 10.9, indicating high tensile strength.Cevap
  3. C
    The bolt has a 10-inch shank length and a thread count of 9 threads per inch.
  4. D
    The bolt head requires a specialized 10.9 mm wrench opening for proper torque application.

Cevap

The stamped marking indicates that the bolt is a metric fastener belonging to Property Class 10.9, denoting a high tensile strength.
On automotive and industrial fasteners, decimal numerical stamps (such as 8.88.8, 10.910.9, and 12.912.9) identify ISO metric property classes. A marking of 10.910.9 indicates a quenched and tempered medium carbon alloy steel bolt with high tensile strength (nominal tensile strength of 1040 MPa1{}040\text{ MPa}), commonly used in high-stress chassis and suspension applications.

Adım Adım Çözüm

1
Analyze the stamping format on the hex bolt head.
The marking is a two-digit decimal number (10.910.9).
Metric fasteners use embossed decimal numbers to represent mechanical property classes, whereas SAE fractional fasteners use radial lines.
2
Interpret the meaning of the metric Property Class designation.
Property Class 10.910.9 specifies a minimum tensile strength of approximately 1000 MPa1{}000\text{ MPa} and a yield strength that is 90%90\% of the tensile strength (900 MPa900\text{ MPa}).
The first number multiplied by 100100 gives nominal tensile strength in megapascals, and the decimal indicates the ratio of yield strength to tensile strength.

Anahtar Kavram

Metric Fastener Property Class Identification
Tahmini Süre:45s
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Bolts, Nuts, and Washers

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