86L20 Steel: Properties and Key Applications

86L20 Steel is a low-alloy steel grade primarily classified as a medium-carbon alloy steel. It is characterized by its specific composition, which includes significant amounts of carbon, manganese, and chromium. The alloying elements in 86L20 contribute to its mechanical properties, enhancing its strength, toughness, and wear resistance.

This steel grade is known for its excellent machinability and weldability, making it a popular choice in various engineering applications. Its primary characteristics include good tensile strength, moderate hardness, and excellent ductility, which allow it to withstand significant mechanical stress without failure.

Advantages and Limitations

Advantages:
- High Strength-to-Weight Ratio: 86L20 offers a favorable balance of strength and weight, making it suitable for applications where weight reduction is critical.
- Good Machinability: This steel can be easily machined, allowing for efficient production processes.
- Weldability: It can be welded using standard techniques, which is advantageous for fabrication.

Limitations:
- Corrosion Resistance: Compared to stainless steels, 86L20 has limited resistance to corrosion, making it less suitable for harsh environments.
- Heat Treatment Sensitivity: The properties can vary significantly with heat treatment, requiring careful control during processing.

Historically, 86L20 has been utilized in various sectors, including automotive and machinery, due to its balance of properties and cost-effectiveness.

Alternative Names, Standards, and Equivalents

Standard Organization	Designation/Grade	Country/Region of Origin	Notes/Remarks
UNS	G86200	USA	Closest equivalent to AISI 8620
AISI/SAE	8620	USA	Minor compositional differences to be aware of
ASTM	A29/A29M	USA	General specification for alloy steels
EN	1.6523	Europe	Equivalent grade in European standards
DIN	20MnCr5	Germany	Similar properties, but with different alloying elements
JIS	SCr420	Japan	Comparable grade with slight variations
GB	20CrMn	China	Equivalent with minor differences in composition

The table above highlights various standards and equivalents for 86L20 steel. Notably, while AISI 8620 is often considered an equivalent, it may exhibit slight variations in mechanical properties and chemical composition that could affect performance in specific applications.

Key Properties

Chemical Composition

Element (Symbol and Name)	Percentage Range (%)
C (Carbon)	0.18 - 0.23
Mn (Manganese)	0.60 - 0.90
Cr (Chromium)	0.40 - 0.60
Mo (Molybdenum)	0.15 - 0.25
Si (Silicon)	0.15 - 0.40
P (Phosphorus)	≤ 0.035
S (Sulfur)	≤ 0.040

The primary alloying elements in 86L20 steel include carbon, manganese, and chromium. Carbon enhances hardness and strength, while manganese improves hardenability and toughness. Chromium contributes to wear resistance and overall strength, making it a critical element for applications requiring durability.

Mechanical Properties

Property	Condition/Temper	Test Temperature	Typical Value/Range (Metric)	Typical Value/Range (Imperial)	Reference Standard for Test Method
Tensile Strength	Annealed	Room Temp	620 - 750 MPa	90 - 110 ksi	ASTM E8
Yield Strength (0.2% offset)	Annealed	Room Temp	350 - 450 MPa	50 - 65 ksi	ASTM E8
Elongation	Annealed	Room Temp	20 - 25%	20 - 25%	ASTM E8
Hardness (Brinell)	Annealed	Room Temp	200 - 250 HB	200 - 250 HB	ASTM E10
Impact Strength	Charpy V-notch	-20 °C	30 - 50 J	22 - 37 ft-lbf	ASTM E23

The mechanical properties of 86L20 steel make it suitable for applications requiring high strength and toughness. Its tensile and yield strengths indicate that it can withstand significant loads, while its elongation percentage shows good ductility, allowing for deformation without fracture.

Physical Properties

Property	Condition/Temperature	Value (Metric)	Value (Imperial)
Density	Room Temp	7.85 g/cm³	0.284 lb/in³
Melting Point/Range	-	1425 - 1540 °C	2600 - 2800 °F
Thermal Conductivity	Room Temp	45 W/m·K	31.2 BTU·in/(hr·ft²·°F)
Specific Heat Capacity	Room Temp	460 J/kg·K	0.11 BTU/lb·°F
Electrical Resistivity	Room Temp	0.00065 Ω·m	0.00038 Ω·in

The density of 86L20 steel indicates it is relatively heavy, which is typical for alloy steels. Its thermal conductivity is moderate, making it suitable for applications where heat dissipation is necessary. The specific heat capacity suggests it can absorb a reasonable amount of heat before experiencing significant temperature changes.

Corrosion Resistance

Corrosive Agent	Concentration (%)	Temperature (°C/°F)	Resistance Rating	Notes
Chlorides	3-10	20-60 / 68-140	Fair	Risk of pitting
Sulfuric Acid	10-20	20-40 / 68-104	Poor	Not recommended
Sodium Hydroxide	5-10	20-60 / 68-140	Fair	Susceptible to stress corrosion cracking

86L20 steel exhibits moderate resistance to corrosion in various environments. It is particularly susceptible to pitting in chloride environments and shows poor performance in acidic conditions. Compared to stainless steels, such as 304 or 316, 86L20's corrosion resistance is significantly lower, making it less suitable for applications in highly corrosive environments.

In comparison to other alloy steels, such as AISI 4140, 86L20 may offer better machinability but at the cost of lower corrosion resistance. This trade-off should be considered when selecting materials for specific applications.

Heat Resistance

Property/Limit	Temperature (°C)	Temperature (°F)	Remarks
Max Continuous Service Temp	400 °C	752 °F	Suitable for moderate temperatures
Max Intermittent Service Temp	500 °C	932 °F	Short-term exposure only
Scaling Temperature	600 °C	1112 °F	Risk of oxidation beyond this temp

At elevated temperatures, 86L20 steel maintains its mechanical properties up to a certain limit. However, beyond its maximum continuous service temperature, it may experience oxidation and loss of strength. This makes it suitable for applications that involve moderate thermal exposure but not for high-temperature environments.

Fabrication Properties

Weldability

Welding Process	Recommended Filler Metal (AWS Classification)	Typical Shielding Gas/Flux	Notes
MIG	ER70S-6	Argon + CO2	Preheat recommended
TIG	ER70S-2	Argon	Post-weld heat treatment may be required

86L20 steel is generally considered to have good weldability. However, preheating is often recommended to prevent cracking, especially in thicker sections. Post-weld heat treatment can also enhance the properties of the weld joint.

Machinability

Machining Parameter	[86L20 Steel]	[AISI 1212]	Notes/Tips
Relative Machinability Index	70	100	Good for machining
Typical Cutting Speed (Turning)	30 m/min	50 m/min	Adjust based on tooling

86L20 steel offers good machinability, though it is not as easy to machine as some free-cutting steels like AISI 1212. Optimal cutting speeds and tooling should be employed to achieve the best results.

Formability

86L20 steel can be cold and hot formed, but care must be taken to avoid work hardening. The minimum bend radius should be considered during forming operations to prevent cracking.

Heat Treatment

Treatment Process	Temperature Range (°C/°F)	Typical Soaking Time	Cooling Method	Primary Purpose / Expected Result
Annealing	600 - 700 / 1112 - 1292	1 - 2 hours	Air	Softening, improving ductility
Quenching	850 - 900 / 1562 - 1652	30 minutes	Oil or Water	Hardening
Tempering	400 - 600 / 752 - 1112	1 hour	Air	Reducing brittleness, improving toughness

Heat treatment processes significantly affect the microstructure and properties of 86L20 steel. Annealing softens the material, while quenching increases hardness. Tempering is crucial to reduce brittleness and improve toughness, making it suitable for various applications.

Typical Applications and End Uses

Industry/Sector	Specific Application Example	Key Steel Properties Utilized in this Application	Reason for Selection
Automotive	Gears and Shafts	High strength, good machinability	Durability and performance
Machinery	Crankshafts	Toughness, wear resistance	Reliability under load
Oil & Gas	Valve Components	Corrosion resistance, strength	Performance in harsh environments

Other applications include:
- Structural components in machinery
- Tooling and dies
- Fasteners and bolts

86L20 steel is chosen for these applications due to its balance of strength, toughness, and machinability, making it suitable for components that experience dynamic loads.

Important Considerations, Selection Criteria, and Further Insights

Feature/Property	[86L20 Steel]	[AISI 4140]	[AISI 8620]	Brief Pro/Con or Trade-off Note
Key Mechanical Property	Good strength	Higher strength	Moderate strength	4140 offers higher strength but less machinability
Key Corrosion Aspect	Fair	Fair	Good	8620 has better corrosion resistance
Weldability	Good	Moderate	Good	4140 may require preheating
Machinability	Good	Moderate	Good	4140 is harder to machine
Formability	Moderate	Poor	Good	8620 is more formable
Approx. Relative Cost	Moderate	Higher	Moderate	4140 is generally more expensive
Typical Availability	Common	Common	Common	All grades are widely available

When selecting 86L20 steel, considerations include its mechanical properties, cost-effectiveness, and availability. While it offers good performance for many applications, alternatives like AISI 4140 or AISI 8620 may be more suitable depending on specific requirements, such as higher strength or better corrosion resistance.

In summary, 86L20 steel is a versatile medium-carbon alloy steel with a range of applications across various industries. Its balance of properties makes it a reliable choice for components that require strength, toughness, and machinability, while its limitations in corrosion resistance should be carefully considered in the selection process.