ETD 150 Steel: Properties and Key Applications

ETD 150 steel is a medium-carbon alloy steel known for its excellent machinability and good mechanical properties. Classified as a low-alloy steel, ETD 150 is primarily composed of iron, carbon, and a small percentage of alloying elements such as manganese, chromium, and molybdenum. These elements enhance its hardness, strength, and wear resistance, making it suitable for various engineering applications.

Comprehensive Overview

ETD 150 steel is characterized by its medium carbon content, typically ranging from 0.15% to 0.25%. The presence of alloying elements like manganese (Mn), chromium (Cr), and molybdenum (Mo) contributes to its overall performance. Manganese improves hardenability and tensile strength, while chromium enhances corrosion resistance and toughness. Molybdenum aids in increasing the steel's strength at elevated temperatures.

The most significant characteristics of ETD 150 include its high tensile strength, good ductility, and excellent machinability. These properties make it a preferred choice for manufacturing components that require precision machining and high wear resistance, such as gears, shafts, and fasteners.

Advantages:
- Excellent Machinability: ETD 150 is designed for easy machining, making it ideal for precision components.
- Good Strength and Toughness: It offers a balance of strength and ductility, suitable for various mechanical applications.
- Versatile Applications: Its properties allow it to be used in diverse industries, including automotive and aerospace.

Limitations:
- Moderate Corrosion Resistance: Compared to stainless steels, ETD 150 may not perform well in highly corrosive environments.
- Limited High-Temperature Performance: While it can withstand moderate temperatures, it is not suitable for applications requiring extreme heat resistance.

Historically, ETD 150 has been widely used in the manufacturing of precision components, contributing to its established market position as a reliable choice for engineers and manufacturers.

Alternative Names, Standards, and Equivalents

Standard Organization	Designation/Grade	Country/Region of Origin	Notes/Remarks
UNS	G15000	USA	Closest equivalent to AISI 4140
AISI/SAE	4140	USA	Minor compositional differences
ASTM	A108	USA	Standard specification for cold-finished steel bars
EN	42CrMo4	Europe	Similar properties, used in European applications
JIS	SCM440	Japan	Equivalent with slight variations in composition

The table above highlights the various standards and equivalents for ETD 150 steel. Notably, while AISI 4140 is often considered an equivalent, it may have slightly different mechanical properties and heat treatment responses, which can affect performance in specific applications.

Key Properties

Chemical Composition

Element (Symbol and Name)	Percentage Range (%)
C (Carbon)	0.15 - 0.25
Mn (Manganese)	0.60 - 0.90
Cr (Chromium)	0.90 - 1.20
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 ETD 150 steel play crucial roles in defining its properties:
- Carbon (C): Increases hardness and strength through heat treatment.
- Manganese (Mn): Enhances hardenability and tensile strength.
- Chromium (Cr): Improves toughness and corrosion resistance.
- Molybdenum (Mo): Increases strength at elevated temperatures and enhances hardenability.

Mechanical Properties

Property	Condition/Temper	Typical Value/Range (Metric)	Typical Value/Range (Imperial)	Reference Standard for Test Method
Tensile Strength	Annealed	620 - 850 MPa	90 - 123 ksi	ASTM E8
Yield Strength (0.2% offset)	Annealed	350 - 550 MPa	51 - 80 ksi	ASTM E8
Elongation	Annealed	20 - 30%	20 - 30%	ASTM E8
Hardness (Brinell)	Annealed	200 - 250 HB	200 - 250 HB	ASTM E10
Impact Strength (Charpy)	-40°C	30 - 50 J	22 - 37 ft-lbf	ASTM E23

The mechanical properties of ETD 150 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 suggests good ductility, allowing for deformation without fracture. The hardness values indicate its resistance to wear, making it ideal for components subjected to friction.

Physical Properties

Property	Condition/Temperature	Value (Metric)	Value (Imperial)
Density	-	7.85 g/cm³	0.284 lb/in³
Melting Point	-	1425 - 1540 °C	2600 - 2800 °F
Thermal Conductivity	20°C	45 W/m·K	31 BTU·in/h·ft²·°F
Specific Heat Capacity	20°C	460 J/kg·K	0.11 BTU/lb·°F
Electrical Resistivity	20°C	0.0000017 Ω·m	0.0000017 Ω·in

Key physical properties of ETD 150 steel include its density and melting point, which are critical for applications involving weight considerations and thermal management. The thermal conductivity indicates its ability to dissipate heat, making it suitable for components that may experience thermal cycling.

Corrosion Resistance

Corrosive Agent	Concentration (%)	Temperature (°C/°F)	Resistance Rating	Notes
Chlorides	Varies	Ambient	Fair	Risk of pitting corrosion
Acids	Varies	Ambient	Poor	Not recommended
Alkaline Solutions	Varies	Ambient	Fair	Moderate resistance

ETD 150 steel exhibits moderate corrosion resistance, particularly in environments with chlorides, where it may be susceptible to pitting. In acidic conditions, its performance declines significantly, making it unsuitable for applications exposed to strong acids. Compared to stainless steels, ETD 150 is less resistant to corrosion, which should be considered when selecting materials for specific environments.

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	450 °C	842 °F	Short-term exposure only
Scaling Temperature	600 °C	1112 °F	Risk of oxidation beyond this temp
Creep Strength considerations begin	300 °C	572 °F	Significant loss of strength above this temp

At elevated temperatures, ETD 150 steel maintains its strength up to approximately 400 °C (752 °F) but may experience oxidation and scaling beyond this point. Its performance in high-temperature applications is limited compared to other alloy steels designed for such environments.

Fabrication Properties

Weldability

Welding Process	Recommended Filler Metal (AWS Classification)	Typical Shielding Gas/Flux	Notes
MIG	ER70S-6	Argon + CO2 mix	Good for thin sections
TIG	ER70S-2	Argon	Clean welds, low distortion
Stick	E7018	-	Suitable for thicker sections

ETD 150 steel is generally considered weldable, but preheating may be required to avoid cracking. Post-weld heat treatment can enhance the properties of the weld zone, ensuring structural integrity.

Machinability

Machining Parameter	ETD 150	AISI 1212	Notes/Tips
Relative Machinability Index	100	150	ETD 150 is less machinable than 1212
Typical Cutting Speed (Turning)	80 m/min	120 m/min	Adjust for tool wear

ETD 150 offers good machinability, though it is not as easy to machine as some free-machining steels like AISI 1212. Optimal cutting speeds and tooling should be considered to achieve the best results.

Formability

ETD 150 exhibits moderate formability, allowing for cold and hot forming processes. However, care must be taken to avoid excessive work hardening, which can lead to cracking during bending operations. Recommended bend radii should be adhered to for optimal results.

Heat Treatment

Treatment Process	Temperature Range (°C/°F)	Typical Soaking Time	Cooling Method	Primary Purpose / Expected Result
Annealing	600 - 700 °C / 1112 - 1292 °F	1 - 2 hours	Air	Reduce hardness, improve ductility
Quenching	800 - 850 °C / 1472 - 1562 °F	30 minutes	Oil	Increase hardness and strength
Tempering	400 - 600 °C / 752 - 1112 °F	1 hour	Air	Reduce brittleness, enhance toughness

Heat treatment processes significantly affect the microstructure of ETD 150 steel. Annealing softens the steel, while quenching increases hardness. Tempering is crucial to balance hardness and 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	High tensile strength, good machinability	Precision and durability
Aerospace	Fasteners	Corrosion resistance, strength	Lightweight and strong
Machinery	Shafts	Toughness, wear resistance	High load-bearing capacity

Other applications of ETD 150 steel include:
- Construction: Used in structural components due to its strength.
- Manufacturing: Ideal for precision tools and dies.

ETD 150 is chosen for applications requiring a combination of strength, machinability, and wear resistance, making it a versatile option across various industries.

Important Considerations, Selection Criteria, and Further Insights

Feature/Property	ETD 150	AISI 4140	SCM440	Brief Pro/Con or Trade-off Note
Key Mechanical Property	Good strength	Excellent strength	Good toughness	ETD 150 is more machinable than 4140
Key Corrosion Aspect	Fair	Good	Fair	4140 offers better corrosion resistance
Weldability	Good	Moderate	Moderate	ETD 150 is easier to weld than 4140
Machinability	Good	Moderate	Fair	ETD 150 is easier to machine than SCM440
Formability	Moderate	Moderate	Good	SCM440 can be formed more easily
Approx. Relative Cost	Moderate	Higher	Moderate	ETD 150 is cost-effective for precision parts
Typical Availability	Common	Common	Common	All grades are widely available

When selecting ETD 150 steel, considerations should include its mechanical properties, machinability, and cost-effectiveness. While it offers excellent machinability and strength, its corrosion resistance may not meet the needs of all applications. Comparing it with alternatives like AISI 4140 and SCM440 can help determine the best fit for specific engineering requirements.

In summary, ETD 150 steel is a versatile medium-carbon alloy steel that excels in machinability and mechanical properties, making it suitable for a wide range of applications. Its selection should be based on a careful evaluation of the specific requirements of the intended use, considering both its advantages and limitations.