AISI D2 Tool Steel Research Articles

Effect of tempering temperature and subzero treatment on microstructures, retained austenite, and hardness of AISI D2 tool steel

The presence of retained austenite in the hardening process of tool steel often causes the lower hardness compared to the hardness requirements and poor dimensional stability in the tool steel. The purpose of the present research is to determine the relationships between the tempering process with and without cryogenic treatment to the hardness and retained austenite amount of as-hardened D2 tool steel. The austenitizing temperature was 1020 °C, the tempering temperatures have variations of 180 °C, 280 °C, 380 °C, 480 °C, and 580 °C, and the subzero treatment has a temperature of −172 °C, followed by tempering at 180 °C, 380 °C, and 580 °C. This study aims to determine the appropriate treatment to obtain a minimum retained austenite percentage to prevent and mitigate the failure of AISI D2 tool steel in the industrial application process. An optical microscope with image processing software (Image-J analysis), as well as Brinell and Vickers hardness testing, is the characterization method used in this work. In general, plate martensite, bainite, retained austenite, and primary and secondary carbides are the phases contained in the microstructure. Tempering temperatures have the effect of increasing the secondary carbide precipitation and decreasing the retained austenite content (γr 3,671%–2,769%). However, the cryogenic treatment can provide a more efficient martensitic phase transformation process and minimal retained austenite content (γr 2,257%–1,199%). The increase in tempering temperature causes a decrease in hardness at a temperature of 180 °C–380 °C. On the other hand, the secondary hardening and phase transformation phenomena cause an increase in the hardness of the as-tempered sample at a temperature of 480 °C, before the sample reexperiences a significant decrease in hardness at a temperature of 580 °C due to diffusion that decreases the carbon content.

Effect of deep cryogenic processing cycles on surface roughness, dimensional stability and microstructure of high carbon high chromium tool steel for cutting tool and dies applications

Abstract The main objective of this investigation is to analyze the influence of DCT cycles on microstructural evolution, surface roughness, hardness and dimensional stability of AISI D2 tool steel for cutting tools and dies applications. The cryogenic quenching was done using gaseous nitrogen. The AISI D2 tool steel was subjected to two DCT cycle: DCT-I (Hardening + DCT + tempering) and DCT-II (Hardening + tempering + DCT). The dimensional stability of AISI D2 tool steel was evaluated using standard Navy C-ring test. The coordinate measuring machine (CMM) was employed for the precise measurement of Navy C-ring subjected to different DCT cycle. The surface roughness was evaluated with R a (arithmetic mean roughness) and R t (total height of roughness profile) values using surface roughness tester. The microstructural features were analyzed using optical (OM) and scanning electron microscopy (SEM). The electrical resistivity and hardness of treated samples were measured using micro-Ohm meter and Vickers microhardness tester. Results showed that AISI D2 tool steel treated with DCT-I cycle exhibited greater surface finish, hardness and dimensional stability compared to DCT-II cycle. It is mainly attributed to the greater precipitation of finer carbides and balancing of tensile-compressive residual stresses.

Measurement and Analysis of Magnetic Properties in IS 2062 Steel and AISI D2 Tool Steel Via Non-destructive Testing

Measurement and Analysis of Magnetic Properties in IS 2062 Steel and AISI D2 Tool Steel Via Non-destructive Testing

Improvement of Frictional Property of AISI D2 Tool Steel Surface against JIS SPFC 980Y Advanced High-Strength Steel by Using Laser Texturing Process

Surface friction in metal forming processes can be reduced by creating lubricant reservoirs at the interface between surfaces in contact, and a laser texturing process can be employed to produce the micro-dimples that act as the reservoirs on the surfaces. However, the role of the laser texturing parameters in the friction reduction of tool steel surfaces has still received very little attention. Therefore, this study aims to reduce the friction of the AISI D2 tool steel surface on which a nanosecond pulse laser was applied to create an array of micro-lubricant pockets for trapping lubricant. The effects of laser power, irradiation duration, and spacing distance between pockets on the pocket diameter, size of the heat-affected zone, surface friction, and wettability were investigated in this work. The average laser power in the range from 5 to 10 W and laser irradiation duration of 0.02 to 0.10 s were applied. The results showed that the increase in laser power and irradiation duration enlarged the pocket diameter and heat-affected zone. The largest pocket diameter of 40 µm was achievable by using 10 W laser power together with 0.10 s irradiation time. The pin-on-disc method was employed to determine the friction coefficient of the tool steel, where JIS SPFC 980Y advanced high-strength steel was used as a disc. The friction coefficient of laser-textured with different spacing distances of 150, 200, and 250 µm versus untextured surfaces was compared and found to vary depending on the applied normal load. The laser-textured surface having a pocket spacing distance of 150 µm and pocket density of 5.6%, offered the lowest friction coefficient of 0.097 on average for all tested loads, whereas the average friction coefficient of the untextured surface was 0.117. In addition, the wettability of textured surfaces was insignificantly changed compared to that of untextured ones, so the micro-lubricant pockets did not cause oleophobicity affecting the performance of lubrication. Well-defined micro-pockets using the most appropriate laser parameters, i.e., 10 W laser power with 0.10 s irradiation duration and 150 µm spacing distance, successfully reduced the sliding friction of contacting couples between the laser-textured tool steel and advanced high-strength steel surfaces. The low surface friction induced by the laser-fabricated micro-lubricant pockets has been feasible for the forming tool and die applications where the energy consumed in their operations can be minimized.

A novel powder-metallurgical eco-friendly recycling process for tool steel grinding sludge

This work comprehensively investigates the reuse of AISI D2 tool steel grinding sludge as secondary raw material into a powder metallurgical process route. The tool steel grinding sludge initially contains about 15 mass% of silicon carbide and aluminium oxide abrasive particles as well as residual cooling lubricant emulsion consisting of water and oil leading to an increased carbon content of 2.56 mass%. A three-stage decontamination procedure of the grinding sludge is performed, including drying, removing non-metallic abrasive particles via magnetic separation, and recovering the cooling lubricant oil by supercritical carbon dioxide extraction. Subsequently, the prepared grinding metal chips are densified by a novel energy efficient short-time sintering technique called electric discharge sintering. The carbon content of the sludge could be reduced to 1.71 mass%. However, it was found that remaining contaminations lead to a change in the alloying composition of the recycled material, which influences the tempering behavior. Increased carbon and silicon levels promoted a high retained austenite fraction after quenching of more than 67 vol%. By adopting the heat treatment, the hardness of the recycled samples could be adjusted to a level similar to that of the cast reference material in quenched and tempered condition. Reducing the retained austenite content to 2.3% by tempering led to a hardness of roughly 700 HV1.However, the recycled material showed less than 40% of the compressive strength of the cast reference material. On the one hand, the lower compressive strength can be attributed to the inadequate removal of oxidic abrasive particles during the recycling process and their poor integration into the metal matrix of the compacted specimens. In addition, oxidized layers on the chip surfaces counteract metallurgical bonding between the chips during electric discharge sintering.

Influence of nano-minimum quantity lubrication with MoS2 and CuO nanoparticles on cutting forces and surface roughness during grinding of AISI D2 steel

Environmental side effects of machining lubricants are the main reasons for the progressive development of utilizing the minimum quantity lubrication (MQL) method instead of conventional methods. Owing to the high specific energy of cutting and generation of more heat in grinding, the MQL technique has a lower efficiency than conventional methods. However, by adding nanoparticles to the base oil, the lubrication efficiency in grinding can be enhanced. In this research, grinding of cold work tool steel AISI D2 was studied using a MQL technique by adding MoS2 and CuO nanoparticles to two types of vegetable-based oils: colza and soybean with different concentration percentages, and their effects were examined on the cutting forces (normal and tangential forces) and surface roughness. The results indicated that the values of normal force and tangential forces diminished by 19 and 35 % when using CuO nano powder in soybean base oil with a concentration of 4 % and MoS2 nano powder in soybean base oil with a concentration of 2 %, respectively. Furthermore, when using CuO nano powder in colza base oil and with a concentration of 2 %, the surface roughness had a significant reduction of 77 % in comparison with pure oil as a grinding fluid.

Effectiveness of using liquid nitrogen cryogen in grinding to enhance the grinding performance of hard steel

Grinding generates a lot of heat in the grinding zone area during operation. Therefore, it is important to keep the temperature under control by using various cutting fluids to get a good ground surface quality. The existence of a stiff air layer surrounding the abrasive wheel is known to waste most of the cutting fluid supply in the interface area between the abrasive wheel and workpiece. Due to the high grinding speed, stiff air layers prevent cutting fluids from entering the interface area. Hence, to enhance the grinding performance, cryogenic cooling has been introduced to improve the penetration into the stiff air layer. The current work investigates the grindability of the ground surface of AISI D2 tool steel under different environments: dry, wet, and cryogenic, regarding grinding forces (i.e. tangential and normal force), specific grinding energy, and surface characterisation. This paper also proposed a method to evaluate image-based Abbott–Firestone curve (bearing area curve) parameters to characterise the ground surface topography. Significant reductions in grinding forces (64%–67% and 44%–50% in Ft, 54%–58% and 34%–39% in Fn), low specific grinding energy (64%–67% and 44%–50%), decrease in surface roughness (46%–51% and 30%–36% in Ra, 37%–41% and 31%–35% in Rz), improved 2D and 3D roughness profiles and higher bearing area ratio (89.54%) were observed at 40 µm downfeed in cryogenic cooling environments compared to dry and wet environments, respectively. Thus, observations show the importance of cryogenic cooling across the experimental domain.

Experimental investigation of the low-temperature oil-on-water cooling and lubrication in turning the hardened AISI D2 steel

In this paper, the influence of the cutting speed, feed, and the depth of cut on the cutting force, surface roughness, cutting temperature, and tool wear were experimentally investigated under the low-temperature oil-on-water (LTOoW) cooling and lubrication condition in turning the hardened tool steel AISI D2 (60 ± 1HRC) with the PCBN cutting tool. The results showed that the three-component cutting forces are FY > FZ > FX. The influence of the cutting speed on the cutting temperature is slightly more visible compared to the feed and depth of cut. In this experiment, a satisfactory surface roughness value of 0.54 µm can be obtained, gaining the effect of the turning instead of the grinding. The flank wear values of the PCBN tool are 142 µm and 148 µm at the cutting speeds of 55 and 140 m/min, respectively; however, the flank wear abruptly increases to 668 µm at a 495 m/min, which has a very serious impact on the tool life. The abrasive wear is considered to be a predominant wear mechanism on the flank wear of the PCBN tool. The rake face is dominated by crater wear due to the high temperature, high pressure, high stress, and high friction at the chip-tool interface. Compared with dry hard turning (DHT) condition, the lower surface roughness value, lower cutting temperature, and longer tool life can be obtained at LTOoW.

Experimental investigation on cutting force during end milling of AISI D2 tool steel using AlCrN coated tool

Experimental investigation on cutting force during end milling of AISI D2 tool steel using AlCrN coated tool

Investigation on the effect of grinding wheel for grinding of AISI D3 tool steel under different conditions

The surface finish of ground samples is highly influenced by the grinding parameters, grinding conditions and the type of grinding wheel. This paper emphasizes on the effect of various grinding factors such as the grinding conditions, the type of grinding wheel and operating process parameters like depth of cut and table speed on the surface roughness of the ground samples. Two types of grinding wheels alumina (Al2O3) and cubic boron nitride (CBN) were used for grinding AISI D3 tool steel under dry and wet conditions. The material removal rate and surface roughness were evaluated for all the ground samples. The results showed that wet grinding outperformed dry grinding and provided a better surface finish while using both grinding wheels. Machine Learning was implemented to optimize the grinding parameters. Multi-objective optimization using genetic algorithm was done and a Pareto frontier chart was made to help determine what values for the input parameters would achieve the required outputs such as material removal rate and surface roughness. Two different approaches Genetic Algorithm and Principle Component Analysis were then compared for multi-objective optimization. The type of grinding wheel used had a dominant effect on the surface roughness of ground samples while the depth of cut had a lesser effect.

Microstructure and tensile properties of bulk AISI D2 tool steel fabricated by direct energy deposition

This study investigated the microstructure and tensile properties of AISI D2 tool steel manufactured by direct energy deposition (DED). The effect of standard post-heat treatment on the mechanical properties and deformation behavior of DED AISI D2 was also examined. The as-built AISI D2 manufactured through the DED process showed the eutectic structure in the interdendrite area in addition to dendrites about 4–5 μm wide. After heat treatment, the carbides in eutectic lamellar structure were transformed into the network and needle type secondary carbides. The DED-built material was interestingly composed of austenite, which transformed into martensite after heat treatment. Hardness value for DED-built material was 486.2 ± 10.6 HV, while for heat-treated material the value was 720.1 ± 10.0 HV. Furthermore, post heat treatment led to tremendous increases in yield strength (784 ± 7.7 MPa to 1480 ± 43.0 MPa) and tensile strength (1054 ± 2 MPa to 1794 ± 69.0 MPa). The hardness value, yield and tensile strengths for DED-built AISI D2 were similar to those of heat-treated conventional wrought AISI D2. In addition, brittle fractures were observed in the tensile fracture surfaces regardless of whether heat treatment was applied. In particular, tensile deformed specimen before heat treatment showed deformation-induced martensite transformation in the areas close to the eutectic structures, while after heat treatment interdendritic cracking as well as transdendritic cracking within the matrix were mainly detected. Based on the above results, the deformation behavior and fracture mechanism of AISI D2 manufactured by direct energy deposition were also discussed.

Effect of nano-minimum quantity lubrication on cutting temperature and surface roughness of milling AISI D3 tool steel

Machining is the manufacturing process used to create components that are the right size and shape. For machining processes, numerous cooling methods are employed. Surface finish of workpiece is affected by heat generated at tool workpiece interface because of friction. The machining technologies include conventional cooling, minimum quantity lubrication, cryogenic cooling, and nanofluid cooling. Because of its excellent qualities, AISI D3 is appropriate for creating blanking and shaping tools. It has high strength, good hardenability, and resistance to wear. The major aim of this study is to see how a tiny amount of lubricant combined with TiO2 nanofluids affects the cutting temperature and surface roughness when milling AISI D3 material. The results suggest that using nanoparticles in combination with lubricant reduces cutting temperature and improves surface roughness. Because the cutting fluid's thermal conductivity has increased, adding TiO2 to MQL results in cutting temperatures of 215.6 °C, 207.1 °C, 199.2 °C, and 195.1 °C for 0.3 %, 0.5 %, 0.7 %, and 0.9 % TiO2, respectively. Surface roughness (Ra) values for 0.3 %, 0.5 %, 0.7 %, and 0.9 % TiO2 in MQL are 0.501, 0.498, 0.481, and 0.455, respectively. A 0.9 % TiO2 nanoparticle concentration is believed to be superior for lower cutting temperatures and better surface quality.

Residual stresses and surface topography investigation of AISI D3 tool steel under of ultrasonic vibration assisted wire-EDM

Residual stresses and surface topography investigation of AISI D3 tool steel under of ultrasonic vibration assisted wire-EDM

Barkhausen Noise Signal Analysis of IS 2062 Steel and AISI D2 Tool Steel with Different Range of Magnetizing Frequency and Intensity

Barkhausen Noise Signal Analysis of IS 2062 Steel and AISI D2 Tool Steel with Different Range of Magnetizing Frequency and Intensity

Identification of ductile fracture design curve for hardened quasi-brittle AISI-D2 tool steel to predict shearing tool failure

Tool deformation and fracture during the shearing of ultra-high-strength steel has become a severe problem. Finite element (FE) simulations can help to solve this problem by evaluating improved tool edge designs, but they require the strain/stress range in which no fracture occurs. This study accordingly identified these properties for conventional and improved AISI-D2 tool steels by shearing them in sheet form using harder tools. First, the work-hardening parameters were fitted so that the FE simulation agreed with the measured punching force vs. stroke curves fitted using the Swift and Voce laws for the conventional and improved steels, respectively, at plastic strain levels exceeding 0.1. The plastic strain ε¯p vs. historically averaged stress triaxiality η¯ plots were derived from each element in the FE simulation at the punch stroke corresponding to fracture. The safe zone against ductile fracture was evaluated as a set of ε¯p — η¯ plots, and the exponential curves through the realms of these safe zones were drawn as the ductile fracture design curves. This evaluation suggested a drastically large fracture strain in the negative η¯ region compared with the fracture strain obtained using high-pressure tensile tests also conducted in this study. The effectiveness of the proposed method was confirmed as it clearly indicated the superiority of the improved AISI-D2 steel material.

Fatigue behaviour of laser shock peened AISI D2 tool steel

Laser shock peening (LSP) is an advanced surface enhancement technique capable of imparting beneficial compressive residual stresses, thereby improving metal parts’ fatigue resistance and crack propagation resistance. This study presents the fatigue behaviour of AISI D2 tool steel samples subjected to LSP with a power density of 15 GW/cm2 and a double laser scanning sequence. The effect of LSP on quasi-static tensile properties was also addressed. The fatigue crack propagation was suppressed in LSP-treated samples when tested at ΔK = 10 MPam. The fatigue strength of treated samples was 32.9% higher compared to untreated samples. The LSP-treated samples have shown a larger fatigue fracture surface area than the as-received (AR) sample. In addition, the tendency to form secondary cracks in the fatigue fracture paths decreased due to LSP treatment. LSP treatment can effectively improve the fatigue resistance and crack propagation behaviour of AISI D2 steel. These improvements are due to significant compressive residual stresses in a superficial layer of the material. The present study provides a reference for improving the mechanical properties of AISI D2 steel by laser shock peening.

Effect of laser pulse power on solidification cracking susceptibility in surface processing of a high carbon high chromium tool steel

High carbon, high chromium tool steels are deep hardening steels widely used for cold forming dies. A 400 W Nd:YAG laser was employed to melt the surface of the AISI D2 tool steel with 5 and 6 ms single pulses of laser at 4–10 J energy levels. The microstructural study showed that complete dissolution of large primary carbides occurred during melting, but the cooling rate was too fast to form any primary carbide. Increasing the laser energy (peak power) led to a coarser dendritic microstructure and a reduction in solidification cracking intensity. The analyses indicate that the coarser dendritic structure has promoted the backfilling effect. However, despite having a coarser dendritic structure, the material laser processed with a preheat of 300 °C showed the most severe crack intensity due to the provision of sufficient time in cooling for the formation of a network of brittle carbides in the inter-dendritic regions. The HAZ was found to be sound although reaching a hardness of 750 HV. • A fine columnar dendritic microstructure was formed by laser remelting, which became coarser with increased laser peak power. • Facilitation of the backfilling effect in higher laser peak powers reduced the intensity of solidification cracks.. • The formation of the inter-dendritic carbide phase in the preheated sample increased the solidification cracking intensity.

The influence of DED process parameters and heat-treatment cycle on the microstructure and hardness of AISI D2 tool steel

The impact of both the laser directed energy deposition (DED) process parameters and post-deposition heat-treatment cycles on the microstructural characteristics and hardness are evaluated for cladding AISI D2 tool steel onto annealed AISI D2 substrates. The influences of powder feed rate, and laser scanning speed were assessed. After laser deposition, the DED samples were subjected to various tempering heat-treatment cycles. The microstructural and compositional characteristics of both the ‘as-printed’ and heat-treated DED processed samples were investigated using scanning electron microscopy with energy dispersive X-ray spectroscopy, confocal laser scanning microscopy, and X-ray diffraction. The indentation and scratch hardness responses were assessed to evaluate the effects of various heat-treatment schedules, with comparison made to wrought D2. It was demonstrated that the microstructure of the DED processed samples had a dendritic morphology with columnar grains. Moreover, the hardness values of the DED fabricated parts were found to be higher than an annealed wrought D2, but lower than the quenched D2. Subsequent tempering of the DED printed parts resulted in a final hardness, essentially equivalent to the as-quenched level.

A comparative study on surface topography and microhardness of laser polished-hardened AISI D2 tool steel

Although a laser beam with a small diameter (< 1 mm) can significantly improve surface morphology, the polishing efficiency is very low, and the improvement of surface hardness is negligible. In this work, a novel laser polishing-hardening (LPH) method with integration and high efficiency for the treatment of AISI D2 tool steel using a large-size laser beam (Φ2.8 mm) was proposed, and the effects of laser hardening (LH), laser polishing (LP), and LPH treatments on the surface topography and microhardness were examined. The results show that the LH method had a negligible effect on the surface roughness of the treated sample, while the surface roughness Ra of LP and LPH specimens was reduced by 74.6% and 80.9%, respectively, indicating that the milled surface topography had been significantly improved, especially LPH was more effective in reducing the roughness. Besides, the polishing efficiency of LPH was 10 times that of the LP approach. In terms of hardness improvement, the near-surface microhardness of LH and LPH samples increased by 1.5 times and 1.3 times, respectively, and the effective hardened zone (EHZ) depth was 0.42 mm and 0.24 mm, respectively, demonstrating that these two laser processing methods had a beneficial effect on the cross-section microhardness of D2 tool steel, while the increase of LP on the microhardness was insignificant. The comprehensive analysis of the surface morphology and microhardness of the LPH specimen indicates that LPH was a feasible laser surface treatment method for D2 tool steel. On the premise of ensuring a high surface finish, the polishing efficiency can be remarkably improved, and the subsurface microhardness and EHZ depth of processed specimen can be also significantly increased, which provided a feasible idea for the application of laser surface treatment technology in industrial mold production.

Effect of Post-Heat Treatment on the Impact Toughness and Crack Propagation Mechanism of AISI D2 Tool Steel Manufactured by Direct Energy Deposition

Effect of Post-Heat Treatment on the Impact Toughness and Crack Propagation Mechanism of AISI D2 Tool Steel Manufactured by Direct Energy Deposition