Steel Forgings Research Articles

Metallurgical integrity for economic production of quality steel forgings for advanced applications

Forging imparts tensile and torsional strength, without compromising on toughness, impact strength, and fatigue resistance. Therefore forgings can withstand shock loads and cyclically varying stresses in dynamically stressed components even in adverse service environments. Forging process can accommodate intricate shapes in various sizes and configurations. Irrespective of the category of materials used in forging, there are several underlying critical principles of complex metallurgy. Quality surveillance at every stage from selection of raw material up to the finishing stage is warranted to realize the full potential of expensive materials used and expensively processed and to avoid untoward premature surprise failures. In recent years, forgings in Super alloys, Titanium alloys, Aluminium alloys and Copper alloys have also come into vogue in Aerospace, Nuclear and Advanced Power Plant Applications. However the focus of this paper is limited to advanced alloy Steel Forgings.

Heat Treatment Effect on Microstructure Evolution in a 7% Cr Steel for Forging

Well-defined heat-treatment guidelines are required to achieve the target mechanical properties in high-chromium steels for forgings. Moreover, for this class of materials, the microstructure evolution during heat treatment is not clearly understood. Thus, it is particularly important to assess the steel microstructure evolution during heat treatment, in order to promote the best microstructure. This will ascertain the safe use for long-term service. In this paper, different heat treatments are considered, and their effect on a 7% Cr steel for forging is reported. Results show that, following the high intrinsic steel hardenability, significative differences were not found versus the cooling-step treatment, although prior austenite grain size was significantly different. Moreover, retained austenite (RA) content is lower in double-tempered specimens after heat treatments at higher temperatures.

Evolution of interfacial characteristics and mechanical properties for 316LN stainless steel joints manufactured by hot-compression bonding

Abstract In this study, we report a method to manufacture heavy stainless steel forgings using a newly-developed multilayer hot-compression bonding method. In particular, the interfacial healing mechanism and mechanical properties of hot-compression bonding joints under various deformation and holding conditions were systematically investigated. The results indicate that the bonding interface can be hardly healed when holding at 900 °C and 1000 °C since the interfacial oxides are difficult to decompose at the low temperatures, resulting in poor tensile properties of the bonding joints. As holding temperature increases to 1100 °C, the interfacial oxides are partially decomposed, and therefore the interface bonding effect improves with the partial restoration of tensile properties. Especially, after holding at a higher temperature, i.e., 1200 °C for 18 h, the tensile properties of the bonding joint with deformation strain of up to 35 % can be fully recovered to the level of the base material, owing to the complete decomposition of broken interfacial oxides. Based on the optimal deformation and holding conditions for interface bonding, a heavy plate with excellent mechanical properties was successfully manufactured using the multilayer hot-compression bonding method.

Enhancing mechanical properties of a V + Ti microalloyed bainitic forging steel via tailoring microstructure through controlled forging

To obtain a refined and homogenized microstructure as well as enhanced combination of strength and toughness, the influence of controlled forging on the microstructure and mechanical properties of a Mn–Cr-type bainitic forging steel microalloyed with V + Ti elements was explored. Microstructural characterization shows that the final microstructure of the as-forged steel changed from primarily granular bainite (GB) to primarily lower lath-bainite (LLB) through controlled forging of mainly finish-forging temperature and post-forging cooling rate. The result of physical–chemical phase analysis shows that almost all the added Ti is in the (V,Ti)(C,N) precipitates, while only ~ 7% of the added V is in the precipitates, and there is only a slight increase in the amount of the (V,Ti)(C,N) precipitates with changing forging condition, and their precipitation strengthening is ~ 40 MPa. The tensile properties except the total elongation increase significantly from the GB sample to the LLB sample, and the latter exhibits identical or even higher mechanical properties than conventional quenched and tempered 42CrMo steel except the yield strength. Instrumental impact tests revealed that the crack initiation energy, propagation energy and the ability of arresting crack growth of the LLB sample are significantly higher than those of the GB sample. The reduction and/or even elimination of large blocky M/A, the increase in high-angle boundaries fraction and microstructure refinement are primarily responsible for this enhancement of doubled impact toughness. It is thus suggested that suitable controlled forging is a promising strategy to regulate and control the microstructure and mechanical properties of bainitic forging steel.

Valley Forge Steel: Strategy, Risk and Reward? A Graduate Case in Strategy and Management Accounting Web Appendix

Valley Forge Steel: Strategy, Risk and Reward? A Graduate Case in Strategy and Management Accounting Web Appendix

Valley Forge Steel: Strategy, Risk and Reward? A Graduate Case in Strategy and Management Accounting

Valley Forge Steel: Strategy, Risk and Reward? A Graduate Case in Strategy and Management Accounting

Energy-Saving Hot Open Die Forging Process of Heavy Steel Forgings on an Industrial Hydraulic Forging Press

The study deals with the energy-saving process of hot open die elongation forging of heavy steel forgings on an 80 MN industrial hydraulic forging press. Three innovative energy-saving power supply solutions useful for industrial hydraulic forging presses were analyzsed. The energy-saving power supply of hydraulic forging presses consists in reducing electricity consumption by the electric motor driving the pumps, reducing the noise emitted by pumps and reducing leaks in hydraulic piston cylinders. The predicted forging force as a function of heavy steel forging heights for various deformation temperatures and strain rates was determined. A simulation model of the 80 MN hydraulic forging press is presented, which is useful for determining the time-varying parameters during the forging process. An energy-saving control for the hydraulic forging press based on the forging process parameters’ prediction has been developed. Real-time model predictive control (MPC) was developed based on multiple inputs multiple outputs (MIMO), and global predictive control (GPC). The GPC has been implemented in the control system of an 80 MN industrial hydraulic forging press. The main advantage of this control system is the repeatability of the forging process and minimization of the size deviation of heavy large steel forgings

Characterisation of heterogeneous microstructure in large forged products using nonlinear ultrasonic method

ABSTRACTA comparative study between the ultrasonic attenuation and the nonlinearity is presented for the characterisation of microstructure in large dimension forgings. Results are provided for two austenitic stainless steel forgings of AISI type 304L with a diameter 200 mm, where microscopic observations reveal abnormal grain growth near the surface of one of the forgings. Frequency dependence of the nonlinearity parameter is used to discern variations in grain size in these forgings more precisely than attenuation measurements. The distribution of grain size is shown to have a significant influence on the nonlinearity parameter. Relative changes in the nonlinearity parameter with applied frequency were correlative with the microstructural variations in both the forgings.

Effect of Composition, Microstructure and Hardness after Heat Treatment on Machinability of Steel Forgings

Machining is a major process performed on the forged steels. Any change in composition or heat treatment of these steels changes their microstructure as well as properties. Knowing the limited focus on understanding the machinability of forging steels, this study focuses on comparison of dry machinability of ferritic-pearlitic, quench-tempered and bainitic steels under different cutting conditions with a variation in its composition and heat treatment performed on them. The machinability in the dry condition is assessed in terms of cutting and thrust forces, machining temperature, tool abrasion wear on the flank face of tools and chip segmentation. In ferritic-pearlitic steels, prominent mode of chip segment formation is Mode-II fracture (shearing), whereas in the quench-tempered steels, it changes from Mode-I (tearing) to Mode-II (shearing) as the sulfur content increases. In the case of bainitic steels, Mode-I fracture is often prominent. The ferritic-pearlitic and quench-tempered steels depict a reduction in cutting forces in between 5 and 12% and machining temperature in between 12 and 20% due to addition of sulfur even though its strength is higher due to higher vanadium content.

Finite Element Prediction of Temperature Variation of Material and Dies in Aluminum Forging

Investigation into behaviors of aluminum alloy to be metal formed at the room temperature is conducted in this study. An index is used to evaluate the sensitivity of temperature, that is, index of relative normalized temperature rise to steel called normalized temperature rise index per steel which helps researchers to obtain some insight on new materials based on experiences of steel forging. An investigation to an aluminum alloy shows that the index is quite high, implying that temperature effect as well as rate-dependence effect on the forming processes of aluminum alloy at the room temperature cannot be neglected. Some details of thermomechanical predictions of a relatively high-speed automatic multi-stage forging process of a yoke with highly deformed region are given to reveal the importance of temperature and/or strain rate even in cold forging of aluminum alloy parts with high speed and high strain. All manuscripts must be in English, also the table and figure texts, otherwise we cannot publish your paper. Please keep a second copy of your manuscript in your office. When receiving the paper, we assume that the corresponding authors grant us the copyright to use the paper for the book or journal in question. Should authors use tables or figures from other Publications, they must ask the corresponding publishers to grant them the right to publish this material in their paper. Use italic for emphasizing a word or phrase. Do not use boldface typing or capital letters except for section headings (cf. remarks on section headings, below).

Low and Medium Carbon Advanced High-Strength Forging Steels for Automotive Applications

This paper presents the microstructural and mechanical properties of low and medium carbon advanced high-strength forging steels developed based on the third generation advanced high-strength sheet steels, in conjunction with those of conventional high-strength forging steels. Hot-forging followed by an isothermal transformation process considerably improved the mechanical properties of the forging steels. The improvement mechanisms of the mechanical properties were summarized by relating to the matrix structure, the strain-induced transformation of metastable retained austenite, and/or a mixture of martensite and austenite.

Analysis of degradation processes on shot sleeves made from new Si-Mo cast iron in aluminium high pressure die casting – A case study

Analysis of damages on shot sleeve after 21.500 shots of Al in high pressure die casting machine was carried out. The shot sleeve was made from modified high Silicon Si-Mo cast iron (high silicon-SiMo – CGI shot sleeve material) instead of the common used hot forged tool steel. New material exhibits improved thermal conductivity and acceptable mechanical properties. The progress of the damages is revealed and explained in this study. Relative early formation of longer cracks on the sharp shaped spots of graphite particles and decrease in adhesion between grain boundaries have been identified. Cracks from sharp shaped spots of graphite particles have locally progressed further and linking with other cracks in neighborhood, i.e. also with cracks formed on base of adhesion decreasing between grain boundaries, that resulted in material spalling. This can be attributed to the fatigue nature of thermal (mechanical) loads as a consequence of the mutual effects of thermal stresses (gradient) on the surface layer and the different thermal dilatation properties between graphite particles and matrix material, and the occurrence of stress concentration on the sharp shaped spots of the graphite particles. This approach, i.e. production of shot sleeve by casting, allows to make the price of the unit more economical compared to the existing forged one, made from H11 or H13 grade tool steel.

Effect of vanadium on microstructure and mechanical properties of bainitic forging steel

This investigation attempts to thoroughly explore the effect of microalloying element V on the microstructural characteristics and mechanical properties of 20Mn2SiCrS bainitic forging steel. The results show that the cooling rate range of bainitic transformation was broadened with a 0.13% V addition and mainly a granular bainite microstructure was obtained after post-forging continuous cooling. The addition of V could refine the martensite/austenite (M/A) constituent and inhibit the formation of pro-eutectoid ferrite. Physical-chemical phase analysis revealed that only ~8.5% of the added V was in the V(C,N) precipitate in the as-forged condition, which resulted in relatively small precipitation strengthening (~40 MPa) compared with that in ferritic-pearlitic medium carbon forging steel. The addition of V can enhance the overall mechanical properties of the steel and it is concluded that the primary role of V in the as-forged bainitic forging steel is mainly to promote the formation of bainite and to refine the microstructure especially the M/A constituents as well as to resist softening of the M/A during the post-forging continuous cooling or during subsequent tempering when tempering treatment is necessary.

Integrated modelling of hot forging of low-alloyed steels for an ICME workflow

One of the key aspects of integrated computational materials engineering approach is the integrated modelling of process chains that capture the essential microstructure physics and predict the final properties. In the current work, such an integrated modelling approach is attempted for analyzing the hot forging process for low-alloyed steels. Traditionally, hot forging process is designed with primary focus on the deformation step, with less attention paid to the incorporation of microstructure information flow between its sub-steps of heating, deformation and cooling. Such a siloed approach restricts its integration with other manufacturing processes, and also with design and material selection stages. To address the issue, in this work, a FEM based thermo-mechanical modelling framework, integrating composition dependent microstructure evolution models for heating, deformation and cooling sub-steps, is implemented for hot forging of low-alloyed steels. The evolution of key microstructural features at each sub-step is tracked and fed to the following step. The integrated modelling framework is then used to study the effect of process parameters and macrosegregation in the billet on the distribution of final microstructure and properties obtained for a sample steel upsetting process. Key observations made in the studies are discussed. Ways of representation of the distribution of microstructure and properties across the forged part, that can enable better decision making in the larger perspective of downstream processing and final use, are highlighted. Consequently, the utility of the integrated modelling approach to aid the development of improved process and product design capabilities for hot forged products is established.

Finite element simulation of X20CrMoV121 steel billet forging process using the Deform 3D software

In this article, a three-dimensional finite element analysis using Deform 3D software has been employed to investigate the plastic deformation behavior during forging of X20CrMoV121 steel. The focus was on the influence of forging temperature on the strain, stress and particle flow velocity distribution during the forging process. From the results, it has been shown that the forging process results in inhomogeneous plastic deformation, hence inhomogeneous strain, stress, and particle flow velocity distribution. As the temperature increased from 800 to 1100 °C, the forging loads and the deformation resistance were observed to decrease with an increase. For each temperature, the load increased rapidly with the stroke and then the increase slowed. This behavior was related to the coefficient of friction at the tool sample interface. It was also shown that the maximum effective stress/strain decreased as the forging temperature increased to 1100 °C. It is suggested that 3D finite element simulation by Deform® 3D software is an efficient method for predicting metal flow behavior during the forging process.

ANN-AGCS for the prediction of temperature distribution and required energy in hot forging process using finite element analysis

Abstract This work calculates the flow of stress of deforming metal as a function of temperature, strain and strain rate using a hybrid adaptive genetic algorithm and cuckoo search (ANN-AGCS) model. The flow behavior of material and the temperature variations in hot upsetting process are predicted by using the finite element analysis. To record the hot deformation performance through the force displacement. In this model to perform a hot non isothermal forging of a low carbon steel. A good decision is done between the predicted data and the measured results.

Thermomechanical treatment of Ti and Ti-V microalloyed steel forgings

Thermomechanical treatment of Ti and Ti-V microalloyed steel forgings

Hydrogen embrittlement of a microalloyed bainitic forging steel

The hydrogen embrittlement (HE) of a novel microalloyed bainitic forging steel with a strength level of 1100 MPa was evaluated using electrochemical charging and slow strain rate tensile test method with notched round bar specimens. The results show that the susceptibility to HE of the as-forged bainitic forging steel is notably higher than that of the quenched and tempered (Q&T) steel at same strength level, which is ascribed primarily to the presence of a relatively high amount of large blocky martensite/austenite (M/A) constituents of the former. It was found that low-temperature tempering treatment at 200 °C could significantly alleviate the susceptibility to HE by a relative decrease of ~ 35% of the as-forged bainitic forging steel at no expense of strength and ductility, though its resistance to HE is still a little lower than that of the Q&T steel. Thus, it is suggested that efforts concerning refining of the large blocky M/A through optimizing chemical composition and processing route could help to further alleviate the susceptibility to HE of the tested bainitic forging steel.

Sasol reveals cost overruns, again

Once again, the petrochemical complex Sasol is building in Lake Charles, Louisiana, faces cost overruns. The company says the plant will cost between $12.6 billion and $12.9 billion, up from the $11.6 billion to $11.8 billion it estimated in February. When the project got the go-ahead in 2014, it was supposed to cost $8.1 billion. Sasol faced construction problems such as defective carbon steel forgings for the new ethylene cracker. The firm says the project is 96% complete. A polyethylene plant has started up, an ethylene oxide plant is ready to open, and the cracker will start up in July.

Research on forming characteristic of pulsed selective laser melting

To investigate the forming characteristic and obtain a greater process control of the pulsed selective laser melting (P-SLM), the single melting point and single-track and multi-layer block experiments were conducted to investigate the influence of various process parameters on the forming process of P-SLM. A rapid method for the optimization of parameters based on molten pool characterizations is developed. Furthermore, the relationships between the two key process parameters (exposure time, point distance) and the geometric characteristics of single tracks are investigated by linear regression analysis. The research on the surface morphology and the overlapping rate of single-track experiments shows that the value of P-SLM scanning speed is determined by the diameter of single melting point. With relatively high forming efficiency, the highest value of density can be up to 99.99% when the process parameter of exposure time is 80 μs, the point distance is 48 μm, and the hatch space is 80 μm. The yield strength, tensile strength, and elongation of the best sample are 533 Mpa, 647 Mpa, and 40%, respectively, which are higher than that of 316L stainless steel forgings standard (ASTM A473-13).