This is directed to: steel novices, steel challenged, and people who might otherwise cause harm to themselves, those around them, or pieces of steel.
So, will steel be affected by temperature? That depends. What Temperature? That depends.
Let’s define temperature as “Service Temperature”. That is, the temperature the steel will encounter where it is being used. It is worth mentioning that service temperature may be “Intermittent”, or “Constant”. If the steel is exposed to intermittent temperatures, it is not exposed long enough to thoroughly take upon itself the service temperature. (It just passes in and out of a furnace but not long enough to get as hot as the furnace.) If the steel is exposed to constant temperature, it takes-on the service temperature.
When the steel mill hardens steel to obtain specific properties, it involves heating the steel and cooling it to a very specific formula. If you are now going to expose it to temperatures that approach those used in the original recipe, you increase the chances of changing the original properties (hardness, brittleness, ductility, etc.). That is reason for caution if you are intending to do anything other than drop it or throw it.
The temperature to which the steel was originally heated were specific to the elements that were in the steel. The temperature it was cooled to, as well as the rate of cooling and even the time required to move the steel from one process to another affected the properties obtained.
Heat will affect steel based on the composition of that steel and relative to the past thermal processing that steel has undergone.
Give or take a country mile; steels will melt around 3000°F. Whereas aluminum will melt around 1200°F. Short of those temperatures, you should not have to worry about your steel leaking off the shelf. Steels will begin to soften, however, at a wide range of temperatures based on their chemical composition and the thermal processing that got them to the current hardness.
Temperatures need not be extremely high to begin to lower the properties of the steel. Some of the very hard wear plates found in industrial applications (near diamond hard) will begin to soften at 280° to 350°F. You can cook a pork butt at 280°F.
In very general terms, if you have a very hard piece of steel that will be exposed to elevated temperatures, there is a good chance it may soften. Conversely, if you have a soft steel and expose it to elevated temperatures, you may cause hardening.
In all cases, with known grades or unknown grades of steel; when heat is involved and the steel you are using may be hardened or may be hardenable, exercise caution. (safety glasses, hard hat, gloves, etc.)
-Howard Thomas, July 5th 2018
FAQs
In very general terms, if you have a very hard piece of steel that will be exposed to elevated temperatures, there is a good chance it may soften. Conversely, if you have a soft steel and expose it to elevated temperatures, you may cause hardening.
How is steel affected by heat? ›
Metals are composed of symmetrical structures of atoms known as allotrope. When heat is applied it displaces the atoms from their position causing them to form a new structure. This is known as allotropic phase transformation. Allotropic phase transformation alters the hardness, strength, and ductility of the metal.
What happens to steel at high temperatures? ›
So when the temperature rises in a steel structure the atoms start to vibrate more and more. This thermal agitation, in turn, leads to an increase in interatomic distances and thus causes an expansion in the material.
What happens to structural steel when heated? ›
High Temperature Effects on Steel
During a fire event, the mechanical properties of steel deteriorate under the elevated temperature. A reduction in yield strength, stiffness, and modulus of elasticity can occur. Deflections, local buckling, and twisting of the steel member can also occur.
What temperature will weaken steel? ›
All materials weaken with increasing temperature and steel is no exception. Strength loss for steel is generally accepted to begin at about 300°C and increases rapidly after 400°C. By 550°C steel retains approximately 60% of its room temperature yield strength, and 45% of its stiffness.
Does steel weaken with heat? ›
The strength of steel remains essentially unchanged until about 600°F. The steel retains about 50% of its strength at 1100°F. The steel loses all of its capacity when it melts at about 2700°F. However, for design purposes, it is usually assumed that all capacity is lost at about 2200°F.
Does steel get weaker when heated? ›
The actual structure of metal also changes with heat. Referred to as allotropic phase transformation, heat typically makes metals softer, weaker, and more ductile.
At what temperature does structural steel fail? ›
ASTM E119, is one of the standardized tests for structural steel it assumes failure at 1000 deg F at which fully loaded columns are typically found to fail [2].
At what temperature does steel change properties? ›
Depending on steel's carbon content, they can be heated to specific temperatures (780 oC to 850 oC) and then quenched in oil or water to cool them quickly. The higher the carbon content, the lower the temperature needed to harden the metal. This temperature is also known as the “austenitic crystal phase”.
Does steel expand due to heat? ›
If you're building with steel, you will need to allow for some wiggle room. Steel expands when it's hot and contracts when it's cool—this is known as thermal movement.
This means that above 550°C, the structural steel member doesn't have enough strength to support the structure it is maintaining. This is the limiting or critical temperature.
Does heat make steel expand or contract? ›
What does heat do to metal? The expansion (or contraction) of any material is due to the kinetic energy of its atoms. When a material is heated, the increase in energy causes the atoms and molecules to move more and to take up more space— that is, to expand. This is true of even a solid such as a metal.
Does steel weaken over time? ›
For those who work with steel and other metals, metal fatigue is an important topic to understand. Metal fatigue occurs when a material has been exposed to repeated stress or strain, such as from intense pressure or vibration. Over time this can cause the metal to weaken or even break down entirely in some cases.
What temperature can steel handle? ›
For a prolonged service life, such as 20 years, plain carbon steels are usually limited to a maximum operating temperature of 750°F (399°C); the ½% molybdenum alloy steels to approximately 850°F (454°C); and the stainless steels to considerably higher temperatures depending upon the type used.
At what temperature does steel become brittle? ›
Non-alloyed steel typically becomes brittle at about -30 ºC. Adding expensive metals like nickel, cobalt and vanadium to steel reduces that temperature by strengthening the connections between grains. SOme alloy steels are stronger until -100 Deg C.
Does fire make steel stronger? ›
In metallurgy, there is a process called “tempering”, where materials like iron and steel are heat treated to increase their strength. Ironically, (sorry, couldn't resist) this actually reduces the metal's hardness, but increases its ductility, which is basically its flexibility under pressure.
Can steel withstand high heat? ›
Stainless steel is often referred to as “green material” since it can be recycled an infinite number of times. As for its heat-resistant properties, stainless steel's melting point falls anywhere between 1400 to 1530 °C (2550 to 2790 °F).
