1. Кіріспе
4140 steel is a low-alloy chromium-molybdenum steel.
It offers an excellent combination of strength, қаттылық, және қарсылық киіңіз, making it an ideal candidate for demanding industrial applications.
Бұл мақалада барланған 4140 alloy steel from multiple technical perspectives, оның химиялық құрамы, Механикалық мінез-құлық, heat treatment response, Айналымдылық, corrosion performance, and common uses.
2. Химиялық құрамы 4140 Легірленген болат
The unique performance of 4140 легірленген болат originates from its carefully controlled chemical composition:
| Элемент | Салмақ % | Role in Steel Properties |
|---|---|---|
| Көміртегі (Б) | 0.38–0.43 | Enhances strength and hardenability |
| Хромий (Кр) | 0.8–1.1 | Improves hardness, тозуға төзімділік, және коррозия |
| Марганец (М.на) | 0.75-1.0 | Boosts toughness and deoxidation |
| Молибден (Әзірлеу) | 0.15-0.25 | Enhances creep resistance and depth of hardening |
| Кремний (Жіне) | 0.15–0.35 | Күшті арттырады, improves toughness slightly |
| Фосфор (Б) | ≤ 0.035 | Typically minimized to reduce embrittlement |
| Күкірт (С) | ≤ 0.04 | Added for machinability but can reduce toughness |
Compared to similar alloys like 4130 (Төменгі көміртек) жіне 4340 (higher nickel), 4140 balances strength and machinability, making it a practical and cost-effective solution for many structural applications.
3. Physical Properties of 4140 Болат
| Мүлік | Бағалау | Бірлік | ЕСталдар |
|---|---|---|---|
| Тығыздық | 7.85 | g / cm³ | Төмен легірленген болаттарға тән |
| Серпімділік модулі (Е е) | ~ 205 | Gpa | Stiffness in tension and compression |
| Ығысу модулі (Ж) | ~ 80 | Gpa | Useful for torsional applications |
| Пуассонның қатынасы | 0.27-0.30 | - | Ratio of transverse strain to axial strain |
| Жылу өткізгіштік | 42.6 | М / м / | -Та 100 ° °; decreases slightly with higher temperatures |
| Нақты жылу сыйымдылығы | 475 | Дж / кг | Approximate at room temperature |
| Электрлік кедергісі | 205 | nΩ·m (nano-ohm meters) | Higher than pure iron; low conductivity compared to copper |
| Термиялық кеңейту коэффициенті | ~12.0 | µm/m·K (20-100 ° C диапазон) | Important in designing for thermal cycling or dimensional stability |
| Балқу нүктесі | 1416–1471 | ° ° | Narrower range due to alloying elements |
4. Механикалық қасиеттері 4140 Болат
Айси 4140 is a versatile chromium-molybdenum alloy steel known for its excellent mechanical strength, қаттылық, Шаршауға төзімділік.
Осы 4140 steel properties can vary significantly depending on their heat treatment condition (E.Г., Аяқталды, қалыпқа келтірілген, сөніп қалды, or tempered).
Mechanical Properties Table
| Мүлік | Аяқталды | Сөніп қалды & Tempered (Q&Т) | Бірлік | ЕСталдар |
|---|---|---|---|---|
| Бергі күш | ~655 MPa | Дейін 1,600 МПа | МПа (мегапаскалдар) | Q&T improves strength significantly |
| ~95 ksi | ~232 ksi | кси (imperial) | ||
| Созылу күші | 850–1,000 MPa | 1,000-1,100 МПа | МПа | Typical range after various heat treatments |
| 123–145 ksi | 145–160 ksi | кси | ||
| Үзіліс кезінде созылу | 25-30% | 12-18% | % | Higher ductility in annealed state |
| Ауданның қысқаруы | ~ 50% | ~ 45% | % | Indicator of ductility and formability |
| Қаттылық (Роквелл C) | 18–28 HRC | Up to 50–55 HRC | Ткект | Highly responsive to quenching and tempering |
| Charpy V-Notch Toughness | >54 Ж (Аяқталды) | 20-35 Дж (Q&T at high hardness) | Joules | Performance in impact loading applications |
| Шаршау күші (Шыдамдылық шегі) | ~420 MPa | Дейін 700 МПа | МПа | Dependent on surface finish and loading cycles |
| Серпімділік модулі (Е е) | ~205 GPa | - | Gpa | Stiffness remains constant across conditions |
5. Heat Treatment Behavior of 4140 Легірленген болат
Айси 4140 alloy steel is highly responsive to a variety of heat treatment processes, allowing it to achieve a broad spectrum of mechanical properties tailored to specific engineering applications.
Its chromium and molybdenum content enhance its hardenability, making it especially well-suited for quenching and tempering operations.
Жалпы термиялық өңдеу процестері
| Өңдеу | Typical Temperature Range (° °) | Мақсат |
|---|---|---|
| Ақша салу | 760–790°C | Астық құрылымын тазартады, softens steel, Техникалық жұмыстарды жақсартады |
| Қалыпқа келтіру | 870-900 ° C | Increases uniformity, refines structure, enhances mechanical consistency |
| Сөндіру | ~845–875°C, followed by oil/water/polymer quench | Produces martensitic structure for high hardness and strength |
| Тымбитора | 400-650 ° C (Пост-сөндіру) | Adjusts hardness, relieves internal stress, икемді жақсартады & қаттылық |
| Тамшылар | Quench to 260–400°C, hold until transformation | Produces bainitic structure, reduces distortion, balances strength-toughness |
6. Machinability and Fabrication of 4140 Болат
Айналымдылық
Материал 4140 steel exhibits moderate machinability in its annealed state and becomes more challenging as hardness increases.
Аяқталған жағдайда (typically around 18–22 HRC), it can be machined with high-speed steel or carbide tools, yielding good surface finishes and acceptable tool life.
Дегенмен, once the steel is quenched and tempered to higher hardness levels (such as 30–50 HRC), its machinability decreases.
Бұл кезеңде, Карбид-құрылғы, lower cutting speeds, and rigid machine setups become essential to avoid tool wear and part distortion.
-Ға CNC бұру, араластыру, or drilling operations, using proper cooling methods—particularly flood coolant—helps dissipate heat and improve chip evacuation.
Drilling harder 4140 sections often requires cobalt or carbide-tipped tools, while tapping hardened parts may benefit from thread milling or forming taps rather than conventional cutting taps.
Дәнекерлеу
Дәнекерлеу 4140 steel requires caution due to its high hardenability and risk of cracking.
To mitigate these risks, preheating the workpiece—typically to 200–400°C depending on the thickness—is strongly recommended.
Maintaining an interpass temperature around 200–300°C helps prevent thermal shock and hydrogen-induced cracking.
Дәнекерлеуден кейін, stress-relieving the component at approximately 600–650°C helps restore ductility and reduce residual stresses.
Low-hydrogen electrodes such as E8018-B2 or ER80S-D2 are typically used for filler material to ensure compatibility and reduce porosity.
Сындарлы қосымшаларда, Дәнекерлеуден кейінгі термиялық өңдеу (Птеп) is necessary to maintain the integrity and toughness of the welded zone.
Cold and Hot Forming
4140 alloy steel can be cold worked in its annealed condition, although its higher strength compared to low-carbon steels limits its ductility.
Cold forming processes such as drawing and swaging are possible but require higher forces and may induce residual stresses that necessitate subsequent heat treatment.
Hot working, including forging and hot rolling, is more favorable for steel 4140.
The ideal forging temperature range is between 900°C and 1200°C, with the material typically finished above 850°C.
After hot forming, normalizing or annealing is recommended to refine the grain structure and prepare the steel for final machining or heat treatment.
7. Corrosion Resistance of 4140 Болат
Сол екі арада 4140 alloy steel excels in mechanical strength, it lacks inherent corrosion resistance.
In humid or marine environments, it readily oxidizes unless protected. To counter this, surface treatments such as:
- Нитраж for surface hardening and oxidation resistance
- Қара оксид жабыны for light corrosion protection
- Electroplating or painting in high-humidity environments
8. Common Forms and Standards
4140 alloy steel is available in a wide variety of commercial forms to accommodate diverse industrial applications.
Its availability in different shapes, combined with its excellent mechanical properties and heat treatment versatility, makes it a popular choice in both standard and custom-fabricated components.
Common Forms of 4140 Болат
Manufacturers and fabricators can obtain 4140 steel in numerous forms, depending on the intended use and required processing:
- Дөңгелек жолақтар: Commonly used for shafts, түйреуіштер, берікек, және бекіткіштер, round bars are one of the most frequently supplied forms of steel 4140 due to their versatility in machining and heat treatment.
- Flat Bars and Plates: Ideal for tooling, wear components, and structural parts requiring large surface contact areas.
These forms are also suitable for flame cutting or water jet processing. - Forged Rings and Discs: Used in high-strength rotating machinery such as bearing races, муфталар, және фланецтер.
- Hollow Bars and Tubes: Preferred in applications demanding weight reduction while maintaining strength, such as hydraulic cylinders and pressure-containing parts.
- Blocks and Billets: Suitable for custom machining and large forged components. These are typically used in die-making and heavy industrial equipment.
Industry Standards and Designations for 4140 Болат
| Standard Organization | Белгілеу | Аймақ / ел | Түсіндірме |
|---|---|---|---|
| Астма | ASTM A29 | United States | General specification for hot-wrought bars of carbon and alloy steels |
| Астма | ASTM A322 | United States | Specification for alloy steel bars used in mechanical applications |
| Астма | ASTM A519 | United States | Specification for seamless carbon and alloy steel mechanical tubing |
Сонымен бірге |
Сонымен бірге 4140 | United States | Chromium-molybdenum low-alloy steel for automotive and engineering applications |
| Айси | Айси 4140 | United States | Commonly used designation aligned with SAE 4140 |
| -Да / -Ден | 1.7225 / 42CrMo4 | Еуропа / Германия | European equivalent under EN 10083 for quench and temper steels |
| Ол | SCM440 | Жапония | Japanese equivalent for high-strength alloy steel |
| Еб | 42Крма | Қытай | Chinese equivalent with similar mechanical properties |
9. Өтініштер 4140 Легірленген болат
Болат 4140 is a go-to material in applications requiring strength, қаттылық, and wear resistance under fatigue and shock loading:
- Автомобиль: берікек, ик-жағалаулар, tie rods, білік
- Аэроғарыш: landing gear components, Жетекеткіштер
- Майлау & Газ: drill collars, hydraulic fracturing parts
- Өндіріс: mandrels, өледі, қалыптар, Құрал иелері
Case study: In a comparative fatigue test, a steel 4140 Q&T gear shaft demonstrated 10x the lifespan of a similar design made from mild steel, highlighting its long-term value.
10. Advantages and Limitations of 4140 Легірленген болат
Артықшылықтары:
- Биік Күш-салмақ ratio for structural applications
- Үздік тозуға төзімділік after hardening
- Versatile heat treatment response
- Readily available in multiple forms and standards
Шектеулер:
- Not suitable for Коррозиялық орта without surface protection
- Талап етеді careful welding practices to avoid cracking
- Жоғары шығындар and complexity than plain carbon steels
11. Қорытынды
4140 alloy steel offers a compelling blend of mechanical strength, қаттылық, және қарсылық киіңіз, making it indispensable in performance-critical engineering applications.
When properly heat-treated and protected, it delivers exceptional service life under demanding operating conditions.
Whether for aerospace, энергия, or tooling components, материал 4140 steel remains one of the most trusted and capable materials in modern manufacturing.
Engineers who understand its behavior and processing requirements can fully harness its potential.
Осы Егер сізге сапалы қажеттілік қажет болса, сіздің өндіріс қажеттіліктеріңіз үшін тамаша таңдау 4140 steel parts.
