霸刀数刀具干货分享--零件渗碳与渗氮的区别

渗碳和渗氮都是金属表面化学热处理工艺，旨在通过改变零件表面的化学成分来提高其硬度、耐磨性、疲劳强度等性能。它们的主要区别体现在以下几个方面：

1.核心差异：渗入元素不同

渗碳：向零件表面渗入碳原子的过程。目的是提高表面含碳量。

渗氮：向零件表面**渗入氮原子**的过程。目的是在表面形成氮化物。

2.适用材料不同

渗碳：主要适用于低碳钢和低碳合金钢（含碳量通常在 0.1%-0.25%）。因为心部需要保持较低的碳含量以保证良好的韧性，而表面需要高碳以获得高硬度。典型材料：20, 20Cr, 20CrMnTi 等。

渗氮：主要适用于含有强氮化物形成元素（如 Al, Cr, Mo, V, Ti）的合金钢、工具钢、不锈钢以及铸铁。这些元素能与氮形成非常硬且稳定的氮化物。典型材料：38CrMoAlA（最经典）、3Cr2W8V、Cr12、1Cr18Ni9Ti（奥氏体不锈钢）等。普通碳钢渗氮效果不佳。

3. 处理温度不同

渗碳：通常在 **900°C - 950°C** 的高温下进行（属于奥氏体状态）。这个温度范围是为了让碳在钢中有足够高的扩散速率。

渗氮：通常在 480°C - 580°C的较低温度下进行（属于铁素体状态）。这个温度低于钢的相变点，可以避免心部组织变化导致的变形，同时氮也能有效扩散并与合金元素形成氮化物。温度过高会导致氮化物粗化、硬度下降。

4. 表面硬度与硬化层深度不同

渗碳：表面硬度通常在 58-63 HRC范围内。硬化层（渗碳层+淬硬层）较深，通常在 0.5mm 到 2.0mm 甚至更深，可以通过调整工艺时间来控制。

渗氮：表面硬度非常高，通常能达到1000-1200 HV (约 67-72 HRC)甚至更高，这是由硬质氮化物（如 AlN, CrN, MoN, VN）带来的。硬化层（氮化层，主要是化合物层和扩散层）相对较浅，通常在0.1mm 到 0.6mm左右。过深的渗氮层需要非常长的时间，经济性差。

5. 性能特点不同

渗碳：表面高硬度、高耐磨性。心部保持较好的韧性和强度（强韧性好）。显著提高弯曲疲劳强度和接触疲劳强度（抗点蚀能力）。承载能力强（因为硬化层深）。

渗氮：极高的表面硬度和耐磨性。优异的抗咬合性（抗擦伤、抗胶合）。良好的耐腐蚀性（化合物层，尤其是ε相，能有效抵抗大气、水、碱液等的腐蚀）。较高的热硬性（在较高温度下仍能保持硬度）。显著提高疲劳强度（尤其对缺口敏感性高的零件）。变形极小（是其最大优势之一）。

6. 工艺特点与变形

渗碳：处理温度高，时间长（几小时到十几小时）。零件变形相对较大（高温加热和淬火引起）。渗碳后必须进行淬火和低温回火才能获得表面高硬度。常采用气体渗碳（可控气氛）、真空渗碳等。

渗氮：处理温度低，时间可以很长（几十小时以获得较深渗层）。

零件变形非常小（低温处理，无相变），常作为最终热处理工序。

渗氮后无需淬火，表面高硬度是由氮化物本身提供的。常采用气体渗氮（氨分解）、离子渗氮（等离子体）、盐浴渗氮（QPQ等）。

7. 应用场合不同

渗碳：广泛应用于承受较大冲击载荷、高接触应力、高弯曲应力和需要深层硬化的零件。如：汽车/拖拉机齿轮、轴类、凸轮轴、活塞销、大型轴承套圈等。

渗氮：广泛应用于要求高表面硬度、高耐磨性、高疲劳强度、高精度、低变形、良好耐蚀性或抗咬合性的零件。如：精密机床主轴/丝杠、发动机曲轴/凸轮轴、汽缸套、塑料/铝压铸模具、齿轮（尤其是精密、高速、重载齿轮）、阀杆、阀门、量规、耐磨板等。特别适合形状复杂、热处理后难以精加工或不允许变形的精密零件。

总结对比表：

8.简单来说：需要深层硬化、承受重载冲击的零件（如汽车齿轮）选择渗碳。需要极高硬度、耐磨、耐蚀、抗咬合、变形极小的精密零件（如精密机床主轴、模具）选择渗氮。

Ba Dao Shu Tool Tips Sharing - The Differences between Carburizing and nitriding of Parts

Carburizing and nitriding are both chemical heat treatment processes for metal surfaces, aiming to enhance the hardness, wear resistance, fatigue strength and other properties of parts by altering their surface chemical composition. Their main differences are reflected in the following aspects:

1. Core difference: Different elements are incorporated

Carburizing: The process of penetrating carbon atoms into the surface of parts. The aim is to increase the surface carbon content.

Nitriding: The process of penetrating nitrogen atoms into the surface of a part. The aim is to form nitrides on the surface.

2. Different applicable materials

Carburizing: Mainly applicable to low-carbon steel and low-carbon alloy steel (with a carbon content typically ranging from 0.1% to 0.25%). Because the core needs to maintain a low carbon content to ensure good toughness, while the surface requires a high carbon content to achieve high hardness. Typical materials: 20, 20Cr, 20CrMnTi, etc.

Nitriding: It is mainly applicable to alloy steel, tool steel, stainless steel and cast iron containing strong nitride-forming elements (such as Al, Cr, Mo, V, Ti). These elements can form very hard and stable nitrides with nitrogen. Typical materials: 38CrMoAlA (the most classic), 3Cr2W8V, Cr12, 1Cr18Ni9Ti (austenitic stainless steel), etc. The nitriding effect of ordinary carbon steel is not good.

3. Different processing temperatures

Carburizing: It is usually carried out at a high temperature of 900°C - 950°C (in the austenitic state). This temperature range is designed to ensure that carbon has a sufficiently high diffusion rate in steel.

Nitriding: It is usually carried out at a relatively low temperature of 480°C to 580°C (in the ferrite state). This temperature is lower than the phase transformation point of steel, which can prevent deformation caused by changes in the core structure. At the same time, nitrogen can effectively diffuse and form nitrides with alloying elements. Excessively high temperatures can lead to the coarsening of nitrides and a decrease in hardness.

4. The surface hardness is different from the depth of the hardened layer

Carburizing: The surface hardness is usually within the range of 58-63 HRC. The hardened layer (carburized layer + hardened layer) is relatively deep, usually ranging from 0.5mm to 2.0mm or even deeper, and can be controlled by adjusting the process time.

Nitriding: The surface hardness is extremely high, typically reaching 1000-1200 HV (approximately 67-72 HRC) or even higher, which is brought about by hard nitrides such as AlN, CrN, MoN, and VN. The hardened layer (nitrided layer, mainly compound layer and diffusion layer) is relatively shallow, usually around 0.1mm to 0.6mm. A too deep nitrided layer takes a very long time and is not economically viable.

5. Different performance characteristics

Carburizing: High surface hardness and high wear resistance. The core maintains good toughness and strength (with good toughness and strength). Significantly enhance bending fatigue strength and contact fatigue strength (resistance to pitting corrosion). Strong load-bearing capacity (because the hardened layer is deep).

Nitriding: Extremely high surface hardness and wear resistance. Excellent anti-bite property (anti-scratch, anti-adhesion). Good corrosion resistance (the compound layer, especially the ε phase, can effectively resist corrosion from the atmosphere, water, alkaline solutions, etc.). High thermal hardness (maintaining hardness at higher temperatures). Significantly enhance fatigue strength (especially for parts with high notch sensitivity). Minimal deformation (one of its greatest advantages).

6. Process Characteristics and Deformation

Carburizing: The treatment temperature is high and the time is long (several hours to over ten hours). The part deformation is relatively large (caused by high-temperature heating and quenching). After carburizing, quenching and low-temperature tempering must be carried out to achieve high surface hardness. Common methods include gas carburizing (controlled atmosphere) and vacuum carburizing, etc.

Nitriding: The treatment temperature is low and the time can be very long (several dozen hours to obtain a deeper nitrided layer).

The deformation of the parts is very small (low-temperature treatment, no phase transformation), and it is often used as the final heat treatment process.

After nitriding, there is no need for quenching. The high surface hardness is provided by the nitride itself. Commonly used methods include gas nitriding (ammonia decomposition), ion nitriding (plasma), and salt bath nitriding (QPQ, etc.).

7. Different application scenarios

Carburizing: Widely used in parts that are subject to significant impact loads, high contact stress, high bending stress, and require deep hardening. For example: automotive/tractor gears, shafts, camshafts, piston pins, large bearing rings, etc.

Nitriding: Widely used in parts that require high surface hardness, high wear resistance, high fatigue strength, high precision, low deformation, good corrosion resistance or anti-seizing property. Such as: precision machine tool spindles/lead screws, engine crankshafts/camshafts, cylinder liners, plastic/aluminum die-casting molds, gears (especially precision, high-speed, and heavy-duty gears), valve stems, valves, gauges, wear-resistant plates, etc. It is particularly suitable for precision parts with complex shapes that are difficult to precisely process after heat treatment or do not allow deformation.

Summary and comparison table

Feature Carburizing and Nitriding

Infiltrate elements carbon (C) and nitrogen (N)

Applicable materials: low-carbon steel, low-carbon alloy steel (C≈0.1-0.25%), alloy steel, tool steel, stainless steel, cast iron containing Al, Cr, Mo, V, Ti, etc

Processing temperature: High temperature (900-950°C, austenite zone); low temperature (480-580°C, ferrite zone)

The surface hardness is extremely high (58-63 HRC) and extremely high (1000-1200HV,67-72 HRC).

The hardened layer is relatively deep (0.5-2.0mm) and relatively shallow (0.1-0.6mm).

The strength and toughness of the core depend on the base material and the quenching and tempering state

Extremely high wear resistance

The anti-biting property is generally excellent

Corrosion resistance is not good (subsequent protection is required), especially in the compound layer.

The fatigue strength has been significantly enhanced (bending and contact fatigue), especially notch fatigue.

The heat hardness is generally good

Large deformation (high temperature + quenching) is extremely small (one of the greatest advantages)

Subsequent treatment must be quenching followed by low-temperature tempering without quenching

Typical processes include gas carburizing, vacuum carburizing, gas nitriding, ion nitriding, and salt bath nitriding (QPQ)

Main applications include gears, shafts, camshafts, piston pins, bearings, etc. (heavy load, impact), precision spindles/lead screws, molds, cylinder liners, gears (precision/high-speed), valves, wear-resistant parts (high precision, wear-resistant, corrosion-resistant, anti-seizing)

8. In simple terms: For parts that require deep hardening and can withstand heavy load impacts (such as automotive gears), carburizing is chosen. Nitriding is selected for precision parts that require extremely high hardness, wear resistance, corrosion resistance, anti-seizing, and minimal deformation (such as precision machine tool spindles and molds).

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