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When does steel achieve maximum strength? What is the upper limit of carbon content in steel and what characteristics does it take on after this limit?

At 0.8% carbon the steel achieve maximum tensile strength.

Further additions of carbon will increase hardness, but increases in tensile strength level off. Beyond this point, the corresponding reduction in ductility limits the usefulness of the steel.

The upper limit of carbon content is around 1.4% beyond this, steel takes on the characteristics features of cast iron.


What are the 5 ways steels can be grouped or classified? What are the 3 categories, based on chemical composition?

Chemical composition
Mechanical properties
Heat treatment
Ease of machining
Specific usage

Chemical composition:
Carbon steels
Low-alloy steel
Alloy steel


What is the carbon content for low to very high carbon steels and what are some products made from these steels?

Low-carbon steel has 0.10 to 0.30% carbon and is used to make wheels, welding electrodes, wire, sheet products, nails, tubing, structural steel shapes, plate and bar, forgings.

Medium-carbon steel has 0.30 to 0.60% carbon and is used for machine parts and tools, crankshaft, gears, axles

High-carbon steel has 0.60 to 1.0% carbon and is used for railroad rails, dies; springs, cold chisels, hammers, wrenches, band saws, axes

Very high carbon steel has 1.0 to 1.7% carbon and is used for twist drills, taps and dies, lathe tool files, razors, ball races. Hardness is the prime consideration.


As a rule steel up to what % can be welded?

0.65% beyond this it is not practical or possible to successfully weld high-carbon steel beyond 0.65%


What does chromium increase in steel?

Chromium increases both hardness and hardenability of steel as well as its resistance to abrasion and corrosion. It also increases its tensile strength.


What does cobalt do to steel?

Cobalt improves the high-temperature properties or the magnetic properties of steel. Cobalt is often used in combination with tungsten to develop red hardness, which is the ability to remain hard when red hot


What is copper used in steel for?

Copper is used as an allowing element in steel to increase resistance to atmospheric corrosion.


What is Manganese used for in steel?

Manganse is an effective deoxidizer. It improves the grain structure and surface appearance of steel. It enhances the hardenability, toughness, strength and ductility.


What is Molybdenum used for in steel?

This element produces the greatest hardening effect of any element other than carbon and checks enlargement of the grain structure
Molybdenum also increases shock resistance, high-temperature strength and enhances corrosion resistance.


What is Nickel used for in steel?

Nickel improves the ductility of steel without sacrificing tensile strength. It also improves the low-temperature toughness of steel. Large quantities of nickel (25% to 35%) dramatically increase resistance to corrosion and shock.


What is titanium used for?

Titanium is used to increase the high-temperature strength of steel. It can also stabilize the grain structure of the steel or to act as a deoxidizer


What is tungsten used for in steel?

Tungsten is used to improve the toughness in steel, hardness and wear resistance of the steel, notably at high temperatures. Tungsten in combination with cobalt gives steel red hardness. Tungsten (often in combination with molybdenum and chromium) is used extensively in the high, speed, high temperature steels from which tools are produced


What is Vandium used for in steel?

Vandium is widely used in construction steel to produce a fine grain structure and to promote toughness and shock resistance. Vandium-bearing steel is used in high-strength pressure pipe, steel springs, gears, shafts and axles where fatigue and impact resistance are prime consideration


What is another name for low-alloy steel and where is it extensively used? What percentage of alloying elements defines medium and high-carbon steels and what are they used for?

Less than 5% of alloying elements including carbon is low-alloy steel. A major component of this group is the high-strength low-alloy steel (HSLA) extensively used in structural applications.

5% to 9% are considered medium alloy steels

When the levels of chromium, nickel or manganese reaches 10% ot higher, the steel is considered high-alloy steel. This includes austenitic manganese steel, stainless steel and specialized heat-resistant steel.


What main organization is used for issuing specifications for the following steel products

Structural- steel plate and shaped
Steel sheet
Steel bar
Boilers and pressure vessels

Structural- steel plate and shaped- CSA, ASTM
Steel sheet- AISI
Steel bar- SAE, AISI
Boilers and pressure vessels- ASME

CSA- Canadian standards association
ASTM- American society for testing and materials
SAE- Society of automotive engineers
ASME- American society of mechanical engineers
AISI- American Iron and steel institute


The major classes for AISI/SAE system

1-Carbon steel
2-Nickel steel
3-Nickel chromium steel
5- Chromium steel (not stainless)
6- Chromium-Vandium steel
7- Tungsten-Chromium steel
8- Nickel-Chromium-Molybdenum steel
9- Silicon-manganese and other complex steels