Nitriding and carbonitriding copy
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Nitriding and carbonitriding are heat treatment processes that diffuse nitrogen into the surface of a metal to harden it. Carbonitriding additionally incorporates carbon to create a harder case. Both processes increase wear resistance, fatigue life, and surface hardness, while reducing distortion compared to other hardening methods. They are commonly used to treat aircraft, automotive, tool, and industrial parts.
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Nitriding and carbonitriding copy
- 1. Today we will discuss about
- 2. Introduction BASIT ALI KHAN (2012-IM-124) PRESENTED BY
- 3. OUTLINES of our Presentation We have features for every step of the way Introduction to Processes Mechanism/ Procedure Example & Applications ADVANTAGES & DISADVANTAGES
- 4. Introduction
- 5. Introduction Both Processes are Anti-wear Heat treatments. Nitriding & Carbonitriding
- 6. NITRIDING Nitriding is a heat treating process that diffuses nitrogen into the surface of a metal to create a case hardened surface. Nitriding of steels produces less distortion and deformation than either carburizing or conventional hardening.
- 7. NITRIDING These processes are most commonly used on low-carbon, low-alloy steels. However they are also used on medium and high-carbon steels, titanium, aluminum and molybdenum.
- 8. Carbonitriding CARBONITRIDING Carbonitriding is a metallurgical surface modification technique that is used to increase the surface hardness of a metal, thereby reducing wear. In carbonitriding , atoms of carbon and nitrogen diffuse interstitially into the metal, creating barriers to slip, increasing the hardness and modulus near the surface.
- 9. MECHANISMPROCEDURE Carbonitriding is often applied to inexpensive, easily machined low carbon steel to impart the surface properties of more expensive and difficult to work grades of steel. Surface hardness of carbonitrided parts ranges from 55 to 62 HRC. Carbonitriding
- 12. MECHANISM OF NITRIDING NITRIDING. • Case-hardening process. • Solid ferrous alloy. • Diffuse nitrogen. • At some suitable temperature.
- 13. MEHANISM OF NITRIDING gas nitriding . Salt bath nitriding. plasma nitriding.
- 14. MEHANISM OF NITRIDING •Gas Nitriding •Case-Hardening Process •Nitrogen Introduction •Surface of a Solid Ferrous Alloy •Nitrogenous Gas •Ammonia Chemical Reaction •Nitrogen & Iron •Core Properties Not Effected Temperature Range •495 - 565 ºC •Below Tempering Temperature White Layer By-Product •Thin •Hard Iron Nitride
- 17. MEHANISM OF NITRIDING •Salt bath NITRIDING •Thermo-chemical Diffusion Treatment •Hardening Components With Repeatability. •Use salt nitrogen-containing •Salt Bath, at sub-Critical Temperatures. •Higher diffusion nitrogen •Corrosion Protection
- 19. MEHANISM OF NITRIDING •Vacuum Chamber •Pressure = 0.64 Pa •Pre-Heat Cycle •Surface Cleaning •Intense electric field. •Control Gas Flow •N, H, CH4 •Ionization by Voltage •Blue-Violet Glow •Wear Resistant Layer •PLASMA NITRIDING
- 23. Carbonitriding is similar to gas carburization with the addition of ammonia to the carburizing atmosphere, which provides a source of nitrogen.
- 24. Nascent nitrogen forms at the work surface by the dissociation of ammonia in the furnace atmosphere; the nitrogen diffuses into the steel simultaneously with carbon.
- 25. Typically, carbonitriding is carried out at a lower temperature and for a shorter time than is gas carburizing, producing a shallower case than is usual in production carburizing.
- 26. CARBONITRIDING IN FC-35 ATMOSPHERE Ammonia and CO2 flows are maintained constant through out the process during Carbonitriding in the FC35 process. A typical Carbonitriding process cycle using the FC35
- 28. Carbonitriding (around 850 °C / 1550 °F) is carried out at temperatures substantially higher than plain nitriding (around 530 °C / 990 °F) but slightly lower than those used for carburizing (around 950 °C / 1700 °F) and for shorter times. A typical Carbonitriding process cycle using the FC35
- 29. Carbonitriding forms a hard, wear-resistant case, is typically 0.07mm to 0.5mm thick. Maximum case depth is typically restricted to 0.75mm; case depths greater than this take too long to diffuse to be economical. Its carried out in a salt bath or in a furnace gas atmosphere.
- 37. Crank Shafts, Cam shafts, Gears etc.
- 38. Tools & Dies
- 40. It gives high surface hardness. Nitriding increase wear resistance. It increase the tensile strength and yield point. Improves fatigue life by 30% to 100%. It is good for high temperature applications. ADVANTAGES
- 41. It has a greater resistance to softening during Tempering. The carbonitrided case has better wear and temper resistance than a straight carburized case. It is carried out at a lower temperature and for a shorter time than is gas carburizing. Reduced distortion due to lower temperature. ADVANTAGES
- 42. Since nitrided parts are not quenched, this minimizes distortion or cracking. Whereas in a carburized part, hardness begins to fall at about 200°C, a nitrided part retains hardness up to 500°C. No machining is required after nitriding. Some complex parts which are not carburized satisfactorily, can be nitrided without difficulty. ADVANTAGES
- 43. DISADVANTAGES Asymmetric products could buckle due to unequal cooling effects Maximum dimensions are determined by the furnace dimensions Blind holes cannot be treated during plasma - nitriding. Toughness and impact resistance decrease
- 44. DISADVANTAGES It produces shallower cases. It is not possible to obtain higher core hardness and deeper case depths. Only useful for Plain carbon steel or Low alloy Steel. Ammonia can produce harmful effects. Long cycle times (40 to 100 hours).
- 45. DISADVANTAGES The brittle case formed is Brittle. Only special alloy steels (containing Al, Cr and V) can be satisfactorily treated. High cost of the nitriding process. Technical control required. If a nitrided component is accidentally overheated, the surface hardness will be lost completely and the component must be nitrided again.
- 47. THANK YOU !
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