Enthalpy said:There is no clear limit. Elongation at break, fracture toughness, impact strength and other indicative and non-reproducible figures vary steadily with temperature.
Steel producers use to give figures or curves down to -50°C and these don't look damning. Steel won't break like glass. The need for toughness depends on you part's use: at a gas tank you want deformation without rupture, at a ball bearing any plastic deformation equals a failure.
Brittle fracture is the sudden and complete failure of a material without any noticeable deformation or warning. It occurs when a material is unable to deform plastically and instead breaks under stress.
Low carbon steels are types of steel that have a low carbon content, typically less than 0.25%. They are known for their high ductility and toughness, making them suitable for a wide range of applications.
The temperature range is important because it determines the behavior of low carbon steels. At low temperatures, these steels become more brittle and are more susceptible to brittle fracture, whereas at higher temperatures, they become more ductile and are less likely to fail suddenly.
Brittle fracture can be expected in low carbon steels at temperatures below their ductile-to-brittle transition temperature, which is typically between -40°C and 0°C. However, this temperature range may vary depending on the specific composition and microstructure of the steel.
To prevent brittle fracture in low carbon steels, it is important to operate them within their ductile-to-brittle transition temperature range. This can be achieved by using suitable heat treatments or alloying elements to improve their toughness, or by avoiding sudden changes in temperature during use.