Microstructure analysis of plasma nitrided cast/forged CoCrMo alloys

Wang, Qingliang; Shen, Han

doi:10.1016/j.surfcoat.2010.10.031

Cited by 29 publications

(7 citation statements)

References 19 publications

(20 reference statements)

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“…The expanded -phase layer with CrN in the trace level was formed by the plasma intruding at 673 K. This nitrogen-supersaturation process is common to other studies in the literature [14][15][16]. The nitrogen-supersaturated layer thickness, previously reported, was much less than 10 m.…”

Section: Discussionsupporting

confidence: 71%

“…The hardness by applying 1 N reached 1,620 HV1N, while the bare CoCrMo hardness was 400 HV1N. The reported hardness in Wang et al [14] was 800 HV1N. The nitrided layer with intensive textures has much higher hardness than that studied in the literature [15,16].…”

Section: Hardening In Depth Of the Nitrided Cocrmo Disc At 673 Kmentioning

confidence: 81%

“…The nitrided layer thickness reached 50 m after plasma nitriding AISI304 and AISI316 substrates for 14.4 ks at 673 K. This nitrided layer had a fine-grained, two-phase microstructure so that the average and surface hardness reached to 1,200 HV1N and 1,400 HV1N, respectively, in [11][12][13]. In a similar manner to the lowtemperature plasma nitriding of austenitic stainless steels, CoCr and CoCrMo alloys were also nitrogen-supersaturated to have high nitrogen solubility at the vicinity of their surfaces [14][15][16]. In addition to hardening by nitrogen supersaturation, the original high chromium content to the CoCr matrix was preserved to sustain its high corrosion toughness.…”

Section: Introductionmentioning

confidence: 90%

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Massive Nitrogen Supersaturation to CoCrMo alloys for Surface Microstructure Control

Aizawa

2023

Academia Materials Science

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CoCrMo alloys were plasma nitrided at 673 K for 14.4 ks to form a homogeneous nitrided layer with a thickness of 12 m. This nitrogensupersaturated layer had an expanded -phase with fine CrN precipitates. The nitrogen solute distributed homogeneously with its average content of 5 mass% toward the nitriding front end. This nitrided CoCrMo alloy matrix with its average grain size of 20 m was plastically strained by the nitrogen supersaturation to significantly modify its original crystallographic microstructure. This nitrided layer consists of intensely textured grains with the orientation of (111) in the normal direction. The nitrided and textured layer had higher hardness 1,620 HV1N than the original polycrystalline CoCrMo matrix, 400 HV1N. Its average friction coefficient against the SUJ2 ball in dry was 0.4-0.5 under the applied load of 5 N and the sliding speed of 0.1 m/s.

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Section: Discussionsupporting

confidence: 71%

Section: Hardening In Depth Of the Nitrided Cocrmo Disc At 673 Kmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 90%

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Massive Nitrogen Supersaturation to CoCrMo alloys for Surface Microstructure Control

Aizawa

2023

Academia Materials Science

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“…There are at least five different mechanisms by using the surface modification methods to increase the fretting resistance: (1) to induce a residual compressive stress; (2) to decrease the coefficient of friction; (3) to increase the surface hardness; (4) to alter the surface chemistry; (5) to increase the surface roughness [19]. DOI There's plenty of research that aims to predict the behaviour of steel after nitriding treatments, AISI 5140 [20][21][22][23][24][25], AISI 430 [21], AISI 1045 [22], AISI 4340 [23], AISI 410 [24], API X-65 [26], Fe-Cr alloys [27] and examine changes in the resulting structures of treatment nitrided components by plasma nitriding [28,29,32,33], ion nitriding [30,31,34], plasma nitrocarburizing [35] and salt bath nitriding [5]. On the other hand there's many studies interested to study surface roughness [36,37,38,39,40,41], methods of measurement of surface roughness parameters [43,44,45,47] and others [42,46,48].…”

Section: Introductionmentioning

confidence: 99%

Effect of Salt Bath Nitriding on Surface Roughness Behaviour of Aisi 4140 Steel

Ghelloudj

Hannachi

Djebaili

2017

Acta Metall Slovaca

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In the present research, AISI 4140 steel was nitrided in salt bath to study and analyze the behaviour of the surface roughness. The structural surface characterization behaviour of the nitrided steel was compared to the behaviour of the same steel which was untreated. The nitriding process was implemented in the salt bath component at ten different times (from 1 h to 10 h) when the temperature was constant at (580ºC). The influence of nitriding treatment on structural properties of the material was studied by scanning electron microscopy (SEM), microhardness tester and surface profilometer. It was found that salt bath nitriding was effective in improving the surface properties behaviour of this steel. Experimental results showed that the nitrides ε-Fe2-3(N,C) and γ'-Fe4(N,C) present in the compound layer increase the microhardness (406-502 HV0.3), the initial surface roughness values of nitrided samples were higher than those of unnitrided specimens, it also observed that the increasing the nitriding time increases the surface roughness parameters (Ra, Rq and Rz).Keywords: salt bath nitriding, AISI 4140 steel, microhardness, surface roughness IntroductionSurface topography is an important characteristic that determines, among other things, catalytic activity, electrochemical potential, adhesion, friction coefficient, susceptibility to wear and scuffing failure and aesthetic appearance [1][2]. Salt bath nitriding [3,4,5] is one of the most widely used thermo-chemical methods [6,7,8], which produces strong and shallow case with high compressive residual stresses on the surface of steel components such as gears, crankshafts, dies and tools [9,10,11]. Surface roughness of industrial components strongly affects their performance, i.e, many surface properties such as friction [12][13], surface wear [14], fluid flow in rough pipes [15] and the functioning of vacuum seals [16] are strictly dependent on surface roughness. In addition, surface roughness seems to be important in bioengineering for example in the joints of the bones [17]. Quite often small roughness is desired since small roughness reduces wear and energy loss, but when high friction is needed also the roughness should be larger. Hence, the inspection of surface roughness of the work piece is very important to assess the quality of a component. The quality of surface roughness is an important requirement for coated parts [18]. There are at least five different mechanisms by using the surface modification methods to increase the fretting resistance: (1) to induce a residual compressive stress; (2) to decrease the coefficient of friction; (3) to increase the surface hardness; (4) to alter the surface chemistry; (5) to increase the surface roughness [19].

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“…However, the direct contact with the surrounding medium occurs once the destruction or breakage of the passive film. Surface treatment, such as DLC film [10] or nitridation [11], can improve the wear resistance mainly by increasing surface hardness. However, the much resource costing is thus involved.…”

Section: Introductionmentioning

confidence: 99%