Plasma nitriding in complex post-processing of stainless steel parts obtained by additive laser technology

Considered are the prospects of applying complex post-processing for an additive manufactured product with the deposition of a multilayer composite coating [Ti0.2C0.8/a-C]40 at the final stage. It is shown that heat treatment, finish milling, ion-plasma nitriding and burnishing with a sliding diamond indenter of a PH1 steel part obtained by selective laser melting (SLM) before deposition of a thin-film coating provides the coating with a minimum surface roughness Ra = 82-86 nm and a maximum hardness of 25.2 ± 1.4 GPa with an increase in the microhardness of the entire “coating-substrate” system.

Phase relations and thermomechanical properties of (Gd2Zr2O7)1−x(YbSZ)x based thermal barrier coatings (0 ≤ x ≤ 0.98)

Doped Gd2Zr2O7 materials have interesting properties as thermal barrier coatings (TBC) to replace the YSZ topcoats traditionally used. Here we investigate the thermomechanical properties and phase relations of Gd2Zr2O7 (GZO) alloyed with 5 mol% Yb2O3 stabilized ZrO2 (YbSZ) in the composition range (Gd2Zr2O7)1−x(YbSZ)x, 0 ≤ x ≤ 0.98. With increasing YbSZ content, phase transformations from ordered to disordered pyrochlore to fluorite and tetragonal structures were observed. The thermal expansion coefficient (TEC) and Vickers hardness were correlated showing a maximum hardness (~ 11.5 GPa) and minimum TEC at x = 0.82. At 1000 °C, the TEC for the end members, x = 0 and 0.98, were 11.4 and 11.3 × 10–6 K−1, respectively. The fracture toughness, KIC, showed an average value around 1.5 MPa m0.5 for x ≤ 0.93 and increased significantly at x = 0.98 reaching 5.4 MPa m0.5 due to the presence of a ferroelastic phase. For TBC applications, compounds with x = 0.98 show promise due to high TEC and high KIC. Graphic abstract Fig. 5a summarize the most important results in the manuscript. Showing a significant increase in fracture toughness for compositions with x=0.98.

Post Underwater Wet Welding Heat Treatment by Underwater Wet Induction Heating

Wet welding procedures of Class A structural ship steels frequently fail to comply with the American Welding Society (AWS) D3.6M, Underwater Welding Code, in the maximum hardness criterion for the heat-affected zone (HAZ). The maximum hardness accepted in a welded joint is 325 HV for higher-strength steel (yield strength > 350 MPa). In multi-pass welds, this problem occurs frequently and is restricted to the HAZ of the capping passes. The HAZ of the root and filling passes are softened by the reheating promoted by their respective subsequent passes. This paper presents the results of exploratory research into postweld underwater electromagnetic induction heating. The objective of the research was to evaluate the ability of induction heating to soften the specific high-hardness HAZs in underwater conditions. The results showed that this technique could reduce the maximum HAZ hardness of low-carbon structural ship steel welds to values below 325 HV, which is the maximum accepted by AWS for Class A welds. The induction-heated zone reached a maximum depth of about 10 mm, which is considered adequate to treat the HAZ of cap-ping passes in underwater wet welds.

Pengaruh Kuat Arus Las Terhadap Sifat Mekanis dan Struktur Mikro Sambungan Las Besi Tuang Kelabu menggunakan Elektroda Nikel dengan Proses Pengelasan SMAW

This study aims to determine the effect of welding current on the mechanical properties and microstructure of graycast iron welding joints using nickel electrodes with the SMAW welding process. The research method used wasexperimental study, starting with preparing the workpiece, welding process, making test specimens and testing the weldspecimens. The material to be joined is gray cast iron metal with a butt joint of a 60 ° open seam V open angle. The weldingprocess used uses SMAW with a current of 80 Amperes, 85 Amperes and 90 Amperes. The added material used was anENiFe-Cl type CIN 2 electrode with a diameter of 2.6 mm. Hardness testing was carried out using the Vickers method andmicrostructure testing using an optical microscope. The results showed that the maximum hardness value of the parentmetal occurred at the welding current strength of 85 Amperes, which was 192.17 VHN, then the maximum hardness value ofthe HAZ area occurred at the welding current strength of 85 Amperes, which was 203.46 VHN, while the maximumhardness value of the weld metal was 203.46 VHN. metal) occurred at a welding current of 90 Amperes, which was 211.18VHN. The results of the microstructure observation showed that the matrix formed on the parent metal was pearlite withgraphite in the form of flakes. The micro structure formed in the HAZ area was a martensite structure. Meanwhile, themicrostructure of weld metal consists of an austenite matrix with an even distribution of graphite particles.

The technology of thermal cyclic electrolytic plasma hardening of steels

This work describes the technology of thermal cyclic electrolytic plasma hardening, as well as describes the design features of the electrolytic plasma heater. There are presented the results of the research of medium-carbon steel hardness treated by thermal cyclic electrolytic plasma hardening under different conditions. An industrial installation for thermal cyclic electrolytic plasma hardening of materials was developed to carry out thermal cyclic electrolytic plasma hardening of steels in an automated mode. Tempered layers were obtained on the surface of the samples with average thickness values from 0.5 to 10 mm and hardness up to 750 HV. Experimentally that the alternation of switching on the electric potential at a voltage of U1 = 320 V and U2 = 200 V provides heating of the product surface to a depth of 10 mm. In this case, the maximum hardness of the surface layer (750 HV) practically does not depend on the thickness of the hardened layer. The hardness of the hardened layer of the product gradually decreases from the maximum (750 HV) to the hardness of the base (280-300 HV). The developed installation allows to vary the electrophysical parameters within a wide range: to set the voltage, the duration of processing, the time of switching on and off the voltage.

Deep fried wheat chips added with potato peel flour—Effect on quality parameters

The aim of this study was to investigate some physicochemical, bioactive, nutritional, and sensory properties of wheat chips enriched with potato peel flour (PPF) at six different concentrations (0, 2, 4, 6, 8, and 10% w/w). Lipid content of the samples were in the range of 45.57–27.46 g/100 g and lipid content of chips decreased (by 40%) significantly (P < 0.05) with the incorporation of PPF. Minimum and maximum hardness levels were 13.32 kg and 22.64 kg, as determined in the control sample and the chips enriched with 8 g/100 g PPF, respectively. Total phenolic of the chips was in the range of 364.7–1107.2 mgGAE/kg and increased significantly (P < 0.05) with increasing of the PPF. In addition, total dietary fiber content of the samples also increased (by 20%) significantly (P < 0.05) by PPF incorporation while the in vitro glycemic index content of samples decreased (P < 0.05). Sensory evaluation revealed that the chips with PPF (by 10%) were more preferred. In this study, alternative chips were produced using PPF.

The Effect of Co-Deposition of SiC Sub-Micron Particles and Heat Treatment on Wear Behaviour of Ni–P Coatings

The purpose of the study is to assess the influence of SiC particles and heat treatment on the wear behaviour of Ni–P coatings when in contact with a 100Cr6 steel. Addition of reinforcing particles and heat treatment are two common methods to increase Ni–P hardness. Ball-on-disc wear tests coupled with SEM investigations were used to compare as-plated and heat-treated coatings, both pure and composite ones, and to evaluate the wear mechanisms. In the as-plated coatings, the presence of SiC particles determined higher friction coefficient and wear rate than the pure Ni–P coatings, despite the limited increase in hardness, of about 15%. The effect of SiC particles was shown in combination with heat treatment. The maximum hardness in pure Ni–P coating was achieved by heating at 400 °C for 1 h while for composite coatings heating for 2 h at 360 °C was sufficient to obtain the maximum hardness. The difference between the friction coefficient of composite and pure coatings was disclosed by heating at 300 °C for 2 h. In other cases, the coefficient of friction (COF) stabilised at similar values. The wear mechanisms involved were mainly abrasion and tribo-oxidation, with the formation of lubricant Fe oxides produced at the counterpart.

Pengaruh Paduan Arang Aktif Kayu Belian/ulin Dan Katalisator Kerang Ale-Ale Pada Proses Pack Carburizing Terhadap Perubahan Komposisi Dan Nilai Kekerasan Baja Karbon Rendah (Low Carbon steel) St 37

To increase the hardness and wear resistance of low carbon steels (low carbon steel), it is usually done by a hardening process, namely by adding carbon elements. One of these processes is by using the Pack carburizing method. In this study, the pack carburizing process will be carried out on low carbon steel St 37 using activated charcoal media from ironwood combined with ale-ale shells catalyst with a composition of 10%, 20%, 30% 40% and 50%. Furthermore, composition testing and hardness testing were carried out using the Vickers method. The results of this study in the composition test, there was an addition of carbon due to diffusion and an increase in the maximum hardness of the catalyst composition by 30% with a hardness of 572.6 VHN.

Effect of heat treatment on the microstructure and properties of 25Cr2MoVA petroleum casing steel

The 25Cr2MoVA steel was subjected to various heat treatments. We found that the hardness increased when the quenching temperature was in the range of 870 – 910 °C, and then it decreased for the temperature of 910 – 990 °C. The maximum hardness was 553 HV after quenching from 910 °C. Following quenching from 910°C, the 25Cr2Mo-VA steel was tempered in the temperature range of 560 to 750 °C. With an increase in the tempering temperature, the hardness and tensile strength of the material decreased, while the impact toughness increased; the corrosion resistance increased initially and then decreased. The best heat treatment process for the 25Cr2MoVA steel involved quenching form 910 °C and tempering at 650°C for 1 h, the hardness was 362 HV, the tensile strength reached 1 310 MPa, the impact energy reached 149 J, and the material exhibited the best corrosion resistance.

Investigation of Welds and Heat Affected Zones in Weld Surfacing Steel Plates Taking into Account the Bead Sequence

In this paper, the experimental investigation results of the bead sequence input on geometry, structure, and hardness of surfaced layers after multi-pass weld surfacing are analyzed. Three S355 steel plates surfaced by GMAW (Gas Metal Arc Welding) were tested with three different combinations of six beads. The geometric, structural, and hardness analysis was carried out in the cross-section of the plates in the middle of the welded layers. The dimensions of padded layers, fusion and heat-affected zone, as well as the individual padded weld were evaluated. On the basis of metallographic samples, qualitative and quantitative structure analysis was performed. Hardness measurements in surfacing welds and heat-affected zones in the tested cross-sections of the surfacing layers were carried out. A comparative analysis of structure and hardness, taking into account the thermal implications of the bead sequence, allowed for the formulation of conclusions. Comparative studies have shown differences in properties between heat-affected zones (HAZ) for individual surfacing sequences. These differences were mainly in the dimensions of the surfacing layers, the share of structural components, as well as the uniformity of hardness distributions. Finally, the most favorable sequence in terms of structure and hardness distribution, maximum hardness, and range of hardness has been indicated.