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Things To Think About While Choosing A Metal Grade

What are the different types of Metals?

Carbon Steel: 

Only trace amounts of other elements besides carbon and iron are found in carbon steels. The most common of the four steel grades, this group accounts for 90% of all steel production. Carbon steel is split into three main subgroups according to its amount of carbon: low-carbon steel, up to 0.3% carbon. Medium carbon steel is between 0.3-0.6% carbon, and high carbon steel is over 0.6% carbon. Businesses routinely make these steels in large quantities since they are simple to produce and strong enough to be employed in substantial construction.

Alloy Steel: 

Alloy steels are created by adding additional alloying elements, including nickel, copper, chromium, and even aluminum. These additives enhance the steel’s strength, ductility, corrosion resistance, and machinability.

Stainless Steel: 

Along with other elements, notably nickel, silicon, manganese, and carbon, chromium compensates 10–20% of the makeup of stainless steel as an alloying component. These steels have a higher ability to withstand poor weather and surprisingly high corrosion resistance, making them safe to use in external construction. Additionally, they are commonly utilized in electrical equipment. For instance, the ability of 304 stainless steel to withstand the environment while shielding electrical components from damage makes it highly prized.

Even while different grades, such as 304 stainless steel, have a place in buildings, stainless steel is used in most sectors due to its hygienic properties. These steels are used throughout pipelines, cutting tools, and machinery for the food and medical industries.

Tool Steel: 

As one can guess from the name, tool steels are great for cutting and drilling equipment. Tungsten, molybdenum, cobalt, and vanadium work together to increase thermal stability and all-around toughness. Since they retain their shape even after heavy usage, they are also the ideal material for the bulk of hand tools.

What are the different Grades of Steel?

Steel grading systems enable anyone to categorize distinct steel types according to the varied uses that distinguish them. For instance, the molecular strength of steel may be influenced by how quickly it cools during manufacture. The steel’s duration at critical temperatures also plays a big role in the cooling process. Depending on the heat-treatment technique utilized, two steel sheets with the same alloy content may belong to various classes.

The ASTM Grading System assigns each metal a sequential number corresponding to its unique properties and a letter prefix based on its broad category (“A” is the classification for iron and steel products). The SAE Grading System uses a four-digit number to categorize work. The first two digits indicate the kind of steel and the quantity of alloying components, while the last two indicate the amount of carbon in the metal. Various industries, including government agencies and architects, often use steel grading standards to ensure product consistency and quality. These standards provide a single vocabulary to define steel properties in the most precise terms possible and point product makers toward the right processing and application methods.

What are the 5 Factors to Consider While Choosing Metal Grade?

  • The Operating Environment Will Determine the Best Metal to Use:

Choose the steel grade that will perform the best in a specific environment by considering the conditions that the end product will experience. Crevice corrosion, incredibly low pH, severe stresses, and high temperatures all harm stainless steel’s performance. The austenitic T3XX series of steels, like the popular 316 and 304 alloys, maintain their strength, hardness, and corrosion-resistant properties over the broadest temperature range.

Corrosion resistance is the main factor to consider when selecting austenitic stainless grades. Type 316 even withstands the chloride ions common in chemical processing and marine industries because of the addition of molybdenum. A well-designed structure is considered the best defense against corrosion with any steel grade.

  • Prioritize strength, toughness, and ductility

Consider these three fundamental mechanical characteristics: Strength is the pressure a metal can withstand before breaking or deforming. For example, when a substance is dragged out into a wire or thread, it can change shape without losing strength or breaking. A metal’s capacity to bend and absorb energy before breaking. Chromium is an alloying element that contributes 10–30% to stainless steel, helping it resist corrosion. The nickel inclusion in austenitic grades gives stainless steel the highest levels of toughness and ductility. The most corrosion-resistant grades have the highest chrome, molybdenum, and nickel concentrations. The alloy structure is not the primary consideration when choosing a stainless steel grade.

When selecting a stainless steel grade, alloy content is simply one factor. The material’s processing also has an impact on how it responds mechanically. Steel’s overall quality can vary depending on how long it is kept at various temperatures during the cooling process and how quickly it is cooled. While carbon steels can only be made tougher through heat treatment, austenitic stainless steels can be toughened using cold working methods, including rolling, bending, swaging, or even drawing at a temperature below the recrystallization temperature. Increasing hardness through cold working techniques reduces elongation and impact resistance.

  • Think about Form and Process

Austenitic stainless steel is usually encountered as bars, wire, tubes, pipes, sheets, and plates; however, most of these products must first be further shaped or machined before they can be used for a particular application. For instance, it can be necessary to bend, wind, redraw, machine, weld, or shape the ends of stainless steel tube. If stainless steel is put through machining processes like CNC, drill, ream, bevel cutting, chamfering, knurling, or threading, pick a machining rate that lowers the danger of work hardening. Alternately, pick a “free machining” grade that contains sulfur.

When welding any stainless metal parts, embrittlement in the weld zone is a significant risk. To lessen carbide production, it is recommended to choose a lower carbon grade, like 304 and 304L. The grade 316L can also prove to be effective.

  • Take Customer Preferences Into Account

Stainless steel is a popular material among designers because it may have a variety of aesthetics, including shiny, electropolished “bright” finishes, dull, “pickled,” matte surfaces polished to a specific RMS, and light-absorbing black oxide coatings. Austenitic stainless steel can be given any of these coatings in addition to the usual passivation.

Customers could also require certification for application-specific requirements. For instance, industrial needle tubing composed of hard-drawn austenitic stainless steel should follow ASTM A908 criteria, whereas boiler, superheater, and heat-exchanger tubes should follow ASTM A213 and A249 standards.

There are known to exist more than 12,000 ASTM standards, each of which addresses a specification so that customers are aware of the technical standards evaluated for molecular structure, thermal treatment or temper, and other physical and mechanical attributes.

  • Control material availability and cost.

High-performance austenitic steels are initially the most expensive stainless steels, but they are excellent investments. Choosing a corrosion-resistant material suitable for the application can reduce maintenance, downtime, and replacement costs. It is feasible to compare different materials “apples to apples” and calculate present and future costs using life-cycle costing approaches.

  • Other factors to be considered are:

Thinking about the magnetic reaction: stainless steels come in various families with various physical characteristics. The elements added to the alloy to make stainless steel determine its magnetic characteristics. Because chromium is added, basic stainless steel has a “ferritic” structure and is magnetic. It can be made “martensitic” by adding carbon to harden it.

On the other hand, the most popular stainless steels are austenitic because they have a greater chromium content. There is also nickel, which alters the physical makeup of steel and renders it non-magnetic. Relative magnetic permeability, a measure of magnetic reactivity, is low for austenitic grades. The nickel-rich stainless steel grades, such as those with 316 or 310, are never magnetic.

As a result, one can utilize them in applications where a non-magnetic metal is needed. Choosing the ferritic or martensitic stainless steel grades is advisable if one is seeking stainless steel grades with a high magnetic response (400 series). They are referred to be “ferromagnetic” and have high permeabilities. When looking for ferromagnetic stainless steel grades, consider Duplex grades like 2101 and 2205. Winding-Up, one must choose the stainless steel needed based on its application because there are numerous grades of stainless steel to choose from, each with unique features.

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