Failure analysis of AISI 316L ball valves by salt bath nitriding

The aim of the current work was to analyse the impact of salt bath nitriding on the behavior of the tribological characteristics and surface microstructures of AISI 316L stainless steels. Nitriding was carried out at 580°C for 10 h. The tribological, structural behavior of the AISI 316L before and after salt bath nitriding was compared. The surface microstructures, tribological characteristics, as well as its surface hardness, were investigated using optical microscopy (OM), X-ray diffractometer (XRD), surface profilometer, pin-on-disk wear tester and microhardness tester. In the current work the experimental results showed that a great surface hardness could be achievable through salt bath nitriding technique because of the formation of the so-called expanded Austenite (S-phase), the nitrogen diffusion region. The surface hardness of AISI 316 stainless steel after nitriding process reached 1100 HV0.025 which was six times the untreated sample hardness. The S-phase is additionally expected to the improvement of wear resistance and decrease the friction coefficient.

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The enhancement effect and kinetics of rare earth assisted salt bath nitriding

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2016.07.189 ◽

2016 ◽

Vol 688 ◽

pp. 350-356 ◽

Cited By ~ 11

Author(s):

Mingyang Dai ◽

Chaoyu Li ◽

Jing Hu

Keyword(s):

Rare Earth ◽

Salt Bath ◽

Enhancement Effect ◽

Kinetics Of ◽

Salt Bath Nitriding

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EFFECT OF SALT BATH NITRIDING TIME ON THE PERFORMANCES OF 304 STAINLESS STEEL

Acta Metallurgica Slovaca ◽

10.36547/ams.26.1.458 ◽

2020 ◽

Vol 26 (1) ◽

pp. 4-6

Author(s):

Xiliang LIU ◽

Changjun MAO ◽

Meihong WU ◽

Wei CAI ◽

Mingyang DAI ◽

...

Keyword(s):

Weight Loss ◽

Stainless Steel ◽

Wear Resistance ◽

Salt Bath ◽

304 Stainless Steel ◽

Micro Hardness ◽

Untreated Sample ◽

Nitriding Time ◽

Optimal Duration ◽

Salt Bath Nitriding

In this study, salt bath nitriding was carried out at 565℃ for various times for 304 stainless steel (304SS). The effect of salt bath nitriding time on the microstructure, micro-hardness and wear resistance was investigated systematically. The results showed a nitriding layer was formed during salt bath nitriding, and the thickness of effective hardening layer is duration dependant. The maximum microhardness value of 1200HV0.01 was obtained at optimal duration of 150min, which was five times higher than that of the untreated sample. And the wear resistance could be significantly improved by salt bath nitriding, the lowest weight loss after wear resistance was obtained while nitriding for 150min, which was one tenth of that of untreated sample.

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THE INFLUENCE OF SALT BATH NITRIDING VARIABLES ON HARDNESS LAYER OF AISI 1045 STEEL

Acta Metallurgica Slovaca ◽

10.12776/ams.v22i3.756 ◽

2016 ◽

Vol 22 (3) ◽

pp. 188

Author(s):

Elhadj Ghelloudj ◽

Hamid Djebaili ◽

Mohamed Tahar Hannachi ◽

Abdenour Saoudi ◽

Bilal Daheche

Keyword(s):

Compound Layer ◽

Salt Bath ◽

Case Depth ◽

Nitriding Process ◽

Hardness Profile ◽

Aisi 1045 Steel ◽

Aisi 1045 ◽

Layer Increase ◽

1045 Steel ◽

Salt Bath Nitriding

<span>The aim of this paper is to study and analyze the effects of a surface controlled salt bath nitriding on the microhardness of AISI 1045 steel. The nitriding process were implemented in salt bath component at ten different times (from 1 h to 10 h) when temperature was constant at (520ºC). The nitriding process repeated of another specimens at the same times but the temperature was (580ºC).The microstructure of surface layers was investigated by optical microscopy. Hardness profiles were measured with low-load hardness testing to determine the growth of the case depth after nitriding. Microhardness testing was carried out on samples to investigate the hardness profile at the transition from the compound to the diffusion layer. The microhardness of surface of nitrided sample at 520ºC and 580ºC was observed in the range of 318–430 HV0.3 and 329–421 HV0.3, respectively. Experimental results showed that the nitrides ε-Fe2-3(N,C) and γ’-Fe4(N,C) present in the compound layer increase the microhardness. It is found that salt bath nitriding parameters (time and temperature) improves the microhardness. </span>

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Troubleshooting

10.31399/asm.tb.pnfn.t65900185 ◽

2003 ◽

pp. 185-191

Keyword(s):

Heat Treatment ◽

Treatment Process ◽

Salt Bath ◽

Heat Treatment Process ◽

Ion Nitriding ◽

Gas Nitriding ◽

Salt Bath Nitriding

Abstract Problems often occur during nitriding, just as with any other heat-treatment process. They can take the form of process problems, steel problems, and machining problems. Troubleshooting is a process of elimination and plain detective work. One must be both observant and systematic during the troubleshooting procedure. This chapter discusses the procedure for troubleshooting problems with gas nitriding, salt bath nitriding, and ion nitriding.

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Preparation of ε-Fe(Si)3N Powder Using a Salt Bath Nitriding Reaction and a Study on the Soft Magnetic Properties of the Powder

Materials ◽

10.3390/ma12020228 ◽

2019 ◽

Vol 12 (2) ◽

pp. 228

Author(s):

Yuhua Xu ◽

Zhenghou Zhu ◽

Hui Zhao ◽

Jia Zhou

Keyword(s):

Magnetic Properties ◽

Temperature Dependence ◽

Saturation Magnetization ◽

Salt Bath ◽

Soft Magnetic Properties ◽

Soft Magnetic ◽

Temperature Range ◽

Nitriding Reaction ◽

Salt Bath Nitriding ◽

Fesi Alloy

In this paper, a single phase ε-Fe(Si)3N powder was successfully synthesized through the salt bath nitriding reaction method. The flaky FeSi alloy powder was used as the iron source, and non-toxic CO(NH2)2 was used as the nitrogen source. The nitridation mechanism, the preparation technology, the soft magnetic properties, and the magnetization temperature dependence of the powder were studied. The research result showed that ε-Fe(Si)3N alloy powders were synthesized in a high temperature nitrification system after the surface of flaky FeSi alloy powders were activated by a high-energy ball mill. The optimum nitriding process was nitridation for 1 h at 550 °C. The ε-Fe(Si)3N powder had good thermal stability at less than 478.8 °C. It was shown that ε-Fe(Si)3N powder has good soft magnetic properties, and the saturation magnetization of the powder was up to 139 emu/g. The saturation magnetization of ε-Fe(Si)3N powder remains basically constant in the temperature range of 300–400 K. In the temperature range of 400–600 K, the saturation magnetization decreases slightly with the increase of temperature, indicating that the magnetic ε-Fe(Si)3N powder has good magnetization temperature dependence.

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Effect of QPQ Salt Bath Oxidation on Corrosion Resistance

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.118.209 ◽

2006 ◽

Vol 118 ◽

pp. 209-214

Author(s):

Yuan Hui Li ◽

De Fu Luo ◽

Shao Xu Wu

Keyword(s):

Corrosion Resistance ◽

Water Solution ◽

Salt Spray ◽

Complex Salt ◽

Salt Bath ◽

Neutral Solution ◽

High Corrosion Resistance ◽

Salt Bath Nitriding ◽

Porous Area ◽

Magnetite Film

The QPQ complex salt bath treatment is a type of surface technology which contains mainly salt bath nitriding and post-oxidizing processes. The effect of QPQ oxidizing temperature and duration on the corrosion resistance of QPQ treated specimens has been explored by immersion tests and salt spray tests in this paper. All the specimens were post-oxidized after being nitrided at 570! for 2 hours. The material used in this study were 1020 steel. In the immersion tests, the specimens were immersed in 3‰ H2O2 and 10% NaCl water solution. In the salt spray tests, specimens were salt spray tested using 5% NaCl neutral solution. From the experimental data, for high corrosion resistance, conclusions can be drawn:(1) appropriate temperature should be selected carefully in post-oxidizing stage .Too low or too high temperature would decrease the corrosion resistance. (2) The best post-oxidizing duration should generate magnetite film in porous area and should not collapse. (3) In second oxidizing stage, the porous area has been partly eliminated, so the duration should be less than the duration of post-oxidizing.

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