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FLEXOR® Steel vs Alloy Steel Grades

FLEXOR® is a unique steel which is neither a standard alloy steel nor a standard tool steel, though it is often mistaken for both. FLEXOR® is extremely versatile due to it's unique chemistry and composition. FLEXOR®'s versatility in heat treatment allows for a wide range of physical properties. These properties include higher core hardness, better machinability (especially at higher hardnesses), and dual properties when case hardened.

A higher core hardness typically means a more uniform hardness through any cross section. The more uniform the hardness along with a fine grain microstructure yields a higher fatigue and tensile strength for difficult applications.

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Dual Properties

When FLEXOR® is case hardened it will yield dual properties not typically achievable with other grades of high strength steel. These dual properties combine higher core strength and a high wear resistant surface. FLEXOR®'s carburized case typically consists of .90 Carbon. This means it is more highly alloyed than oil hardening tool steel and will yield significantly better wear properties than other carburizing grades such as 1018 or 8620. The key alloys of Chromium, Molybdenum, and Tungsten produce harder complex carbides which exhibit higher wear resistance. It should be pointed out in the Comparison Chart below that compared to many steels FLEXOR® is almost 2 to 1 in percent of carbide forming alloy.

Machinability

FLEXOR® has a rating of 60% of free machining steel B1112. Many people have remarked how much better the machining is compared to other steels such as 4340 Steel, 4330+V steel, 9310 steel, or 300M steel. This is primarily due to other steels reliance on Nickel as the key alloy for hardenability. Unfortunately for other steels, Nickel also work-hardens which greatly inhibits machinability. FLEXOR® has a very low percentage of Nickel and far better machining characteristics without sacrificing properties.

Distortion

Though FLEXOR® often is used as an alternative to some tool steels it still must be quenched and tempered in an oil hardening process. This process leads to distortion. FLEXOR® is not exempt, however, certain techniques can be employed to reduce distortion and thus grind stock. Other alloy steels lose properties rapidly when these techniques are used. FLEXOR® typically will not be significantly affected.

Alloy Steel Grade Comparison Chart

FLEXOR®'S unique chemistry allows it to be used in thousands of applications often as a superior alternative to other alloy or tool steels. FLEXOR® combines key carbide forming elements, (Cr, Mo, W) to form complex carbides. These carbides increase hardening, wear, and strength properties of the steel. The relatively low amount(s) of Nickel adds to the machinability. The Alloy Comparison Chart below shows the comparison between FLEXOR® and other common grades FLEXOR® has replaced. Note the differences in carbide forming alloy percentages. This is one of FLEXOR®'S keys to success.

Alloy 8620 9310 1018 4130 4140 4150 4340 4330V 6150 O-6 O-1 300M FLEXOR®
Carbon, C
0.200
0.100
0.180
 0.300
0.400
0.500
0.400
0.300
0.500
1.450
0.900
0.420
0.340

Chromium*, Cr

0.500
1.200
0.000
0.900
0.900
0.900
0.800
0.800
0.950
0.200
0.500
0.800
0.850

Molybdenum*, Mo

0.200
0.100
0.000
0.200
0.200
0.200
0.200
0.400
0.000
0.250
0.000
0.380
0.500

Vanadium*, V

0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.070
0.000
0.000
0.000
0.070
0.000

Tungsten*, W

0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.500
0.000
0.500

Nickel, Ni

0.550
3.250
0.000
0.000
0.000
0.000
1.750
1.750
0.000
0.000
0.300
1.800
0.100

Manganese, Mn

0.800
0.550
0.750
0.800
0.800
0.800
0.800
0.850
0.800
0.800
1.200
0.750
0.800

Silicon, Si

0.250
0.250
0.000
0.250
0.250
0.250
0.250
0.300
0.250
1.200
0.500
1.650
0.300

Sulfur, S

0.030
0.020
0.050
0.030
0.030
0.030
0.030
0.006
0.040
0.030
0.030
0.050
0.015

Total % Alloy

2.530
5.470
0.980
2.480
2.580
2.680
4.230
4.476
2.540
3.930
3.930
5.920
3.405

Total % Carbide
Forming Alloy

0.700
1.300
0.000
1.100
1.100
1.100
1.000
1.270
0.950
0.450
1.000
1.250
1.850


*Carbide Forming Alloys Elements are based upon averages and may vary from typicals above.

This is similar to normalizing, but instead of air cooling, the part must be slow cooled in the furnace. The part will become soft, due to carbon being released from solution.

This is achieved with most steels by quenching the steel from the proper austenitizing temperature, into either air, oil or water.  

Hardenability is a function of alloy content. This term is used to designate the depth and distribution of hardness. Reduced core hardnesses are a result of low hardenability, and therefore, low alloy content. Low hardenability, in effect, reduces the overall strength of a part.

Hardness is a function of the total carbon content of a steel, and is relative to the tensile strength and yield strength. The higher the carbon content – the higher the attainable surface hardness! However, hardness alone does not guarantee success in your application. Other factors to consider when selecting the correct steels are listed herein.

The ease to which a material can be turned or milled generally denoted by a percentage of a free machining steel such as B1112. FLEXOR® in the as rolled condition has a rating of approximately 60%.

This is a high temperature draw or temper. The purpose is to eliminate stress from cold working (ie: machining) or welding. The range is usually between 1400 degrees Fahrenheit and 1700 degrees Fahrenheit.

This is usually a low temperature draw or temper. The temperature range to stress relieve most alloy and carbon steels is between 350 degrees and 500 degrees Fahrenheit. The stress relieve temperature of 350 degrees will not reduce the “as quenched” hardness of the part.

After hardening (see above), all steels must be tempered to bring the hardness down into a usable range. This is done by reheating the steel to an approximate temperature of between 350 degrees and 1200 degrees, depending on the type of steel being tempered and hardness required. It is important to note that you must harden and quench the steel in the proper agent, prior to tempering.

This measure is used widely but means little since the part will always fail before the “tensile load” is reached.

Toughness is measured in foot pound force, Izod impact, or Charpy impact tests. The higher the hardness, the lower the toughness. Therefore, caution must be taken to choose a steel where you do not sacrifice toughness for higher hardness. This can result in a brittle part, and possible failure.

Wear resistance is the ability to resist erosion caused by mechanical working or abrasion. Wear resistance is related to hardness, but most importantly it is increased by higher alloy content. Alloys such as chromium, molybdenum, vanadium, and tungsten are all carbide forming alloys. Best wear properties are achieved when higher amounts of these alloys and carbon are used in a steel.

When a steel is cold worked, this area deforms, and will increase in hardness. This increases surface wear properties, but reduces ductility. Nickel based steels such as 9310, 300M, 4330V, and 4340 tend to workharden.

This is the load in which the part will return to its original size after the load is removed.

The FLEXOR® Advantage

Higher core
hardness

Better
machinability

Dual properties
when case hardened

Customized
properties available

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