Superplastic Boronizing Research Articles

Development of Cutting Tool Through Superplastic Boronizing of Duplex Stainless Steel

In this study, a cutting tool is developed from duplex stainless steel (DSS) using the superplastic boronizing technique. The feasibility of the development process is studied, and the cutting performances of the cutting tool are evaluated and compared with commercially available carbide and high-speed steel (HSS) tools. The superplastically boronized (SPB) cutting tool yielded a dense boronized layer of 50.5 µm with a surface hardness of 3956 HV. A coefficient of friction value of 0.62 is obtained, which is lower than 1.02 and 0.8 of the carbide and HSS tools. When tested on an aluminum 6061 surface under dry condition, the SPB cutting tool is also able to produce turning finishing below 0.4 µm, beyond the travel distance of 3000 m, which is comparable to the carbide tool, but produces much better results than HSS tool. Through superplastic boronizing of DSS, it is possible to produce a high-quality metal-based cutting tool that is comparable to the conventional carbide tool.

Development and Kinetics of TiB2 Layers on the Surface of Titanium Alloy by Superplastic Boronizing

The aim of this work is to explore the possibility of combining boronizing and superplastic deformation on titanium alloy (Ti6Al4V) substrate. Superplastic boronizing (SPB) is carried out at three different temperatures of 1173 K, 1223 K, and 1273 K (900 °C, 950 °C, and 1000 °C), and it is held for four different boronizing times of 1, 2, 3, and 6 hours. TiB2 is the only boride compound identified after the boronizing process. Boronized layer thickness in the range of 44.9 ± 1.1 to 149 ± 1 μm is formed on the surface of Ti6Al4V and the surface hardness values increase with respect of the formation’s degree of the hard boronized layer. Diffusion coefficient values attained for all temperatures are (1.44 ± 0.8) × 10−13, (4.1 ± 1.5) × 10−13, and (8.86 ± 4.1) × 10−13 m2 s−1, respectively and the values are higher as compared to other works referred. The activation energy obtained for this process is 226.17 ± 8.3 kJ mol−1. The results obtained suggest that the SPB process provides a more competent and efficient process for the formation of a boronized layer on the alloy.

Superplastic boronizing of duplex stainless steel under dual compression method

In this work, SPB of duplex stainless steel (DSS) under compression method is studied with the objective to produce ultra hard and thick boronized layer using minimal amount of boron powder and at a much faster boronizing time as compared to the conventional process. SPB is conducted under dual compression methods. In the first method DSS is boronized using a minimal amount of boron powder under a fix pre-strained compression condition throughout the process. The compression strain is controlled in such a way that plastic deformation is restricted at the surface asperities of the substrate in contact with the boron powder. In the second method, the boronized specimen taken from the first mode is compressed superplastically up to a certain compressive strain under a certain strain rate condition. The process in the second method is conducted without the present of boron powder. As compared with the conventional boronizing process, through this SPB under dual compression methods, a much harder and thicker boronized layer thickness is able to be produced using a minimal amount of boron powder.

Influence of Strain Rate and Strain on the Surface Properties in Superplastically Boronized Duplex Stainless Steel (DSS)

It was reported that superplastic boronizing process (SPB) provides a much faster boronizing rate than the conventional boronizing process (CB). This process was conducted on duplex stainless steel (DSS) which exhibit superplasticity. The study concentrated on the effect of strain rate and compression strain on SPB. The process was conducted under four different strain rates and three diferent strains condition. Boronizing was successfully conducted with the best result obtained under the high strain rate range of 5 x 10-5 s-1 to 1 x 10-3 s-1 which is associated with the superplastic region. Through SPB, movement of atoms into the specimen was highly accelerated by the grain boundary sliding process leading to a formation of thick and hard boronized layer in extraordinarily short period of time.

Effect of Powder Particle Sizes on the Development of Ultra Hard Surface through Superplastic Boronizing of Duplex Stainless Steel

In this work, a further study on boronizing using compression method called superplastic boronizing (SPB) was conducted. This process was conducted on duplex stainless steel (DSS) that exhibited superplasticity. Efforts were being put in obtaining ultra hard surface through SPB by focusing on the boron powder particle size. The microstructure, hardness, and layer thickness of the boronized materials were investigated. Comparison using as-received DSS with coarse microstructure also was performed. The overall results from the study showed that the SPB process can produced a very hard surface of close to 4000 HV and significantly improved the surface properties of the DSS.

Effect of Powder Particle Sizes on the Development of Ultra Hard Surface Through Superplastic Boronizing of Duplex Stainless Steel

Effect of Powder Particle Sizes on the Development of Ultra Hard Surface Through Superplastic Boronizing of Duplex Stainless Steel

Compression Method for Superplastic Boronizing of DSS

Superplastic boronizing (SPB) is a new surface hardening technique utilizing the ultra high plasticity phenomenon in metals in carrying out boronizing process. In boronizing, boron atoms are diffused into the metal substrate to form a hard boride layer. In this research, a new compression method for the SPB process was introduced. A clamp with an initial compressive load of about 1960 N was used. Thermo-mechanical treated duplex stainless steel (DSS) with fine grain microstructure which can show superplastic behavior at high temperatures was used as the superplastic material. SPB experiments were conducted at temperatures between 1123 and 1223 K for durations of 1 - 6 hours. The boronized specimens demonstrated thin, smooth and compact morphology of boride layer. The boride layer thickness was within ±10 0m - ±46.2 0m. On the boride layer, only the favorable single phase of Fe2B was detected. High value of surface hardness was observed in the range of ±847 HV - ±2914 HV. The overall results from the study show that the SPB process can significantly improve the surface properties of DSS.

Superplastic boronizing of a low alloy steel — microstructural aspects

The formation and mechanisms of the texture growth of boride phases during superplastic boronizing were studied in comparison with conventional boronizing. The texture degree was quantitatively determined by using X-ray diffraction with Lotgering method. The microstructures and distributions of the alloy elements were studied by using SEM and electron probe microanalysis. Microhardness tests across the boride layers were also performed. The results indicated that the superplastic boronizing retarded the formation of the high boron containing boride phases and reduced the growth texture of the borides. Compared with the conventional boronizing, the FeB growth texture was eliminated and Fe 2B growth texture was reduced significantly with the superplastic boronizing. The superplastic boronizing processes also suppressed the formation of the Si-rich zones which otherwise would form between the boride grains. The microhardness of the boride layer processed by the superplastic boronizing was more uniform than that produced by the conventional boronizing.

Improving the mechanical properties of boronized layers by superplastic boronizing

Superplastic boronizing is a new processing technology that combines boronizing with superplastic deformation. This process not only has a much faster boronizing rate compared with the conventional boronizing method, but also produces boronized layers with improved mechanical properties. The present project studies the mechanical properties of a low-alloy steel (0.9C1Si1CrFe) after superplastic boronizing treatment. The results indicate that superplastic boronizing has improved the fracture strength of the specimens by 8%, the toughness by 18% and the maximum flexure by 15%, compared with the conventional boronizing process. Microstructural and microcompositional changes were observed which are believed to effect the mechanical-property improvement. Superplastic boronizing has wide potential applications in the surface modification on steels, and it can be used to study the mechanism of superplastic deformation.

Isothermal superplastic boronizing of high carbon and low alloy steels

Superplasticity has been developed rapidly since the 1960`s. Superplasticity and superplastic deformation technique of steel and ferrous alloys offer a new method of forming complex parts for industrial applications, such as dies and gears. On the other hand, boronizing has long been used to improve the surface properties of dies and tools because boride has high hardness, good wear resistance, and good corrosion and oxidation resistance. Superplastic boronizing, a new technique, is the processes that combines boronizing with superplastic deformation. Because two processes become one, energy and time can be saved. In the present paper, the superplastic boronizing processes for commercial 0.9C-1Si-1Cr-Fe and 1C-1Cr-Fe steels are described first. Then, the microstructure and properties of specimens produced by using superplastic and conventional boronizing are compared. Finally, a physical model for superplastic boronizing processes is suggested.

Isothermal superplastic boronizing of high carbon and low alloy steels

Isothermal superplastic boronizing of high carbon and low alloy steels