Low Carbon Steel (Mild Steel): 

Typically contain 0.04% to 0.30% carbon content. It covers a great diversity of shapes; from Flat Sheet to Structural Beam. Depending on the desired properties needed, other elements are added or increased. For example: Drawing Quality (DQ) – The carbon level is kept low and Aluminum is added, and for Structural Steel the carbon level is higher and the manganese content is increased.

Medium Carbon Steel:

Typically has a carbon range of 0.31% to 0.60%, and a manganese content ranging from .060% to 1.65%. This product is stronger than low carbon steel, and it is more difficult to form, weld and cut. Medium carbon steels are quite often hardened and tempered using heat treatment.

High Carbon Steel:

Commonly known as “carbon tool steel” it typically has a carbon range between 0.61% and 1.50%. High carbon steel is very difficult to cut, bend and weld. Once heat treated it becomes extremely hard and brittle

Alloy steel is a steel that has had small amounts of one or more alloying elements (other than carbon) such as such as manganese, silicon, nickel, titanium, copper, chromium and aluminum added. This produces specific properties that are not found in regular carbon steel. Alloy steels are workhorses of industry because of their economical cost, wide availability, ease of processing, and good mechanical properties. Alloy steels are generally more responsive to heat and mechanical treatments than carbon steels.

Stainless steel is an alloy of Iron with a minimum of 10.5% Chromium (typically between 10-20%). Chromium produces a thin layer of oxide on the surface of the steel known as the ‘passive layer’. This prevents any further corrosion of the surface.

Stainless Steel is valued due to its high corrosion resistance. Stainless steel is about 200 times more resistant to corrosion than mild steel.

Austenitic Stainless Steels.

Most frequently used types of stainless steels.

High chromium and Nickel content compared to other steel alloys, higher resistance to corrosion.

Non-magnetic + Most weld-able + not heat-treatable.

Can be largely divided into three groups: common chromium-nickel (300 series), manganese-chromium-nickel-nitrogen (200 series) and specialty alloys.
Use in food processing equipment, kitchen utensils and medical equipment.

Grade 304 – Chromium 18-20%, Nickel 5-10.5%. include manganese, silicon
Grade 316 – similar to Grade 304 but 316 containing a significant amount of molybdenum; typically 2 to 3 percent, hence increased corrosion resistance.

Ferritic Stainless Steels

Contain trace amounts of nickel, 12-17% chromium, less than 0.1% carbon, along with other alloying elements, such as molybdenum, aluminium or titanium.

Magnetic. Non heat treatable. Can be hardened through cold working.

Good ductility and formability, but high-temperature strengths are relatively poor.

Less expensive because of reduced nickel content.

Grade 430 – Fe, <0.12% C, 16-18% Cr, <0.75% Ni, <1.0% Mn, <1.0% Si, <0.040% P, <0.030% S

usually provided in bar form to be used in automatic screw machines.

Grade 434 – added molybdenum to increase its corrosion

Martensitic Stainless Steels

Contain 11-17% chromium, less than 0.4% nickel and up to 1.2% carbon

Less Corrosion resistance, but high tensile strength & high hardness.

Martensitic stainless steels, such as types 403, 410, 410NiMo and 420 are magnetic and heat-treatable. These Stainless steels are used in knives, cutting tools, as well as dental and surgical equipment.

Grade 420: carbon <0.15%, Chromium 12.0-14.0%, Manganese <1.0%, Silicon <1.0% …

It offers good ductility in its annealed state and excellent corrosion resistance properties when the metal is polished, surface grounded or hardened. This grade has the highest hardness – 50HRC

Duplex (or austenitic-ferritic): Primarily used in chemical plants and piping applications. Duplex stainless steels typically contain approximately 22-25% chromium and 5% nickel with molybdenum and nitrogen. Duplexes have higher yield strength and greater stress corrosion cracking resistance to chloride than austenitic stainless steels.

Both the low nickel content and the high strength (enabling thinner sections to be used) give significant cost benefits. They are therefore used extensively in the offshore oil and gas industry for pipework systems, manifolds, risers, etc and in the petrochemical industry in the form of pipelines and pressure vessels.

Standard Duplex ( PREN Range 28-38) typically Grade EN 1.4462 (also called 2205)

Super-duplex (PREN Range 38-45) Typically grade EN 1.4410 up to so-called Hyper duplex grades (PREN > 45)

Lean Duplex grades (PREN Range 22-27), typically grade EN 1.4362

Precipitation Hardening: This is a chromium-nickel stainless that also contains alloying additions such as aluminium, copper or titanium. These alloys allow the stainless to be hardened by a solution and aging heat treatment. They can be either austenitic or martensitic in the aged condition.

Grade 630 / 17-4 PH. The name comes from the additions 17% Chromium and 4% Nickel. It also contains 4% Copper and 0.3% Niobium.

Cost: 316 Cr+Ni+Moly (Austenitic) > 304 Cr+Ni (Austenitic) > 430 Cr 12-17 (Ferritic) > 420 Cr 12-14 (Martensitic)

Tool steels comprise carbide-forming elements such as chromium, vanadium, molybdenum and tungsten in different combinations. They also contain cobalt or nickel which improves their high-temperature performance. They are generally heat-treated to improve the hardness and used for stamping, forming, shearing and cutting metals and forming of plastics. They are classified according to their composition and properties into various categories.

Classifications

Tools steels fall into three basic categories:

• Cold work tool steels
• Hot work tool steels
• High-speed tool steels

Cold-work steels are further subdivided into:

• Air-hardening
• Medium-alloy cold-work steels
• High-carbon, high-chromium cold-work steels
• Oil-hardening cold-work steels

Hot work steels are subdivided into:

• Chromium
• Tungsten
• Molybdenum hot work steels

High-speed tool steels are divided into:

• Molybdenum
• Tungsten
• Intermediate high-speed steels

Other types of tool steels include:

• Water-hardening tool steels
• Shock-resistant tool steels
• Low-carbon tool steels
• Low-alloy special purpose tool steels.

The following table shows the composition limits of various types of tool steels.