Steel is an extremely popular material. Let’s take a look at its properties and characteristics.
- What are the most important parameters and mechanical properties of steel?
- What are the types of steel?
- What are the markings of steels and how to distinguish them?
- What is ASTM A182 F91 and what are its properties?
What are the types of steel and what properties does it have? Let’s try to learn more about this material.
What are the most important parameters and mechanical properties of steel?
Steel is a material used in many industries and fields. It is the basic material of most structures.
What are the most important properties of steel?
- Hardness, a characteristic related to the content of manganese, carbon and other chemical components. It is the ability of the material to resist when trying to press harder objects.
- Weldability, which is a characteristic of steel that allows the material to be joined by welding. It is used, for example, in the socket welding process.
- Strength, primarily tensile strength, is a characteristic, determined by the amount of stress induced by the force that causes the material to break.
- Elasticity is the ability of a material to recover its original form after deforming forces have acted on it.
- Ductility, which is the ability of a material to retain its altered form after a force ceases to act on it.
- Ductility, which is the ability of a material for retaining its properties during stamping, bending, straightening and others. Thanks to this property, it is possible to process the material.
- Toughness is the ability to withstand dynamic loads.
It is also useful to know the physical properties of steel. It has a density of ρ = 7850 kg/m3. Its thermal conductivity is λ = 58 W/mK, and its coefficient of linear expansion is αT = 0.000012 0C-1. It also has resistivity (20 oC, 0.37-0.42 % carbon) = 171-10-9 [Ω-m] and a Poisson’s ratio of ν = 0.30. Note that depending on the type of steel, it may have slightly different properties. F91 and F92 energy steel, intended for the manufacture of boiler components, will be slightly different from steel intended for knife blades.
What are the types of steel?
Classification of steel is an extremely broad topic. One of the most important distinctions that are taken into account is the chemical composition. Because of it, unalloyed steels and alloyed steels are distinguished. Steel is also distinguished by its application. Thus, a distinction can be made between tool steels, structural steels and others. There are also special steels.
Among the special steels distinguished are:
- stainless steel,
- Acid-resistant steel, or acid-resistant steel,
- Heat-resistant steel,
and others.
What are the markings of steels and how to distinguish them?
Anyone who has dealt with steel knows that the names used are very mysterious. Well, because what is the difference between A335 P91 and A335 P92 or 1.4903 and 1.4901? And for the businessman, the difference is very important. However, the specific designations of the steel are intended to make it easier to recognize its properties and purpose. Hence the first letter in the names – it specifies the purpose of the steel.
Thus, you can meet such designations as:
- B: steel for concrete reinforcing bars
- G: cast steel,
- L: steel for line pipes,
- P: steel for pressure equipment,
- R: steel for rails,
- S: structural steel,
- Y: steel for prestressing strings.
This is followed by three-digit numbers that specify the minimum yield strength of the material. For example, in structural steel the minimum yield strength is usually 235, 275, 355, 420 or 460 MPa. In steel alloys for rails and steel for prestressing strings, the number indicates the minimum tensile strength. The last symbol indicates the type of steel. In the case of unalloyed steels, the yield strength and Gn are indicated in turn, where it can denote unrestrained steel (G1), semi-restrained steel (G2), reassured steel (G3) or steel whose condition is determined by the manufacturer (G4). In the case of alloy steels that are difficult to rust, a W or WP mark is added at the end to denote increased phosphorus content.
Additional designations are for fine-grained alloy steels:
- The first is a letter. It can be N (normalized or normalized-rolled steel), M (thermomechanically rolled steel), Q (quenched steel), A (case-hardened steel).
- Then the second character (L, L1, L2) denotes the breaking work for alloys with the additional designations N, M, Q.
It is worth noting that different types of steel may be marked differently depending on the country. For this reason, it is useful to use the table of stainless steel grades.
What is ASTM A182 F91 and what are its properties?
A182 F91 steel is an alloy steel forged fittings and flanges. It is a high-temperature material with a chromium content of 9% and a molybdenum content of 1%. It is used, like A182 F92 for power generation, chemical processing industries and oil and gas industry. It is also used in high-temperature applications and the aerospace industry.
There are a lot of types of A182 F91 Forged Fittings:
- socket weld fittings,
- steel pipe fittings,
- threaded fittings,
- joint flanges,
- socketweld fittings,
- blind flanges,
- weld neck flanges,
- BS flanges,
- DIN flanges,
- EN flanges.
This steel includes Carbon (0.08-0.12%), Manganese (0.30-0.60%), Phosphorus (0.025%), Sulfur (0.015%), Silicon (0.50-1.00%), Chromium (8.00-9.50%), Molybdenum (0.30-0.60%), and Niobium (0.10-0.30%). Its key properties include elongation (20%), tensile strength (485MPa), and yield strength (275MPa).
