Effect of temperature on fastener strength
Steel boltsISO 898-1 (JIS B 1051)強度区分 X.Y の X×100 が引張強さ、それに Y/10 を掛けた値が耐力になります。Stainless steel fastenersISO 3506-1 (JIS B 1054-1)鋼とは決め方が違い、区分の値を 10 倍した数が引張強さの最小値になります。Non-ferrous fastenersISO 8839 (JIS B 1057)銅合金とアルミニウム合金。強度区分ではなく材質区分と合金番号で決まります。Effect of temperatureJIS B 1054-1 附属書F常温から外れたときの機械的性質。温度ごとの数値が規格にあるのはステンレス鋼だけです。
Stainless steel (elevated temperature)
Stainless steel (low temperature)
Notes
- The elevated-temperature figures are ratios to the room-temperature yield strength, and apply only to property classes 70 and 80.The standard does not say how far the tensile strength falls.
- The low-temperature figures cover austenitic grades only.Martensitic and ferritic grades are not covered by the standard.
- No temperature-by-temperature figures are given for steel bolts.Annex B of JIS B 1051 says only three things: that no harmful effect is known up to 150 °C; that above 150 °C and up to 300 °C the functional properties should be confirmed by test; and that below −50 °C and above 300 °C expert advice should be sought.
- What falls at elevated temperature is lower yield point, 0.2 % proof strength, stress at 0.0048d extension, and tensile strength. Property classes 4.8, 5.8 and 6.8, which are finished by work hardening, are held to be more susceptible to relaxation than quenched and tempered products.
- JIS has no table of values by property class.If you come across such a table, check whether it really comes from the standard.
- JIS B 1057 specifies the mechanical properties of non-ferrous fasteners at room temperature and says nothing about other temperatures.
- Sources: JIS B 1051 Annex B, JIS B 1054-1 Annex F, JIS B 1057