Microstructure and Properties of the 308LSi Austenitic Steel Produced by Plasma-MIG Deposition Welding with Layer-by-Layer Peening

This paper investigates the effect of cold working via layer-by-layer peening on the microstructure and properties of a 308LSi steel workpiece produced by the wire deposition welding with a consumable electrode following the principle of 3D printing. The microstructure, phase composition and mechanical properties of the metal are studied before and after the workpiece synthesis. In the microstructure of the workpieces produced by peening, there is, in addition to austenite, a small quantity of fine-dispersed carbides and residual δ-ferrite in the interdendritic spaces. It is demonstrated that the use of layer-by-layer cold working in the process of deposition welding enables eliminating transcrystallization of the deposited metal, promotes an increase in the microstructure’s degree of dispersion and a more uniform distribution of fine-dispersed carbides in the volume of the dendrites. It is found that these structural features of the deposited metal in the additive manufacturing of a workpiece with layer-by-layer peening lead to an enhancement of the strength characteristics as compared to the material produced by the conventional wire deposition welding. Meanwhile, the level of the ductility characteristics remains high.

Thick Si-doped DLC coatings with high load bearing capacity on cold working tool steels by PECVD

For improving the wear resistance, thick silicon doped hydrogenated amorphous carbon (a-SiC:H) coatings were deposited on cold working tool steels by Plasma Enhanced Chemical Vapor Deposition (PECVD) technology. The increase of the acetylene (C2H2) flow rate distinctly tuned the microstructure of a-SiC:H coatings, including an increase in the coating thickness (>15 μm), a decrease in the silicon content, a greater sp2/sp3 ratio and higher degree of graphitization. The highest hardness of 19.61 GPa and the greatest critical load of 50.7 N were obtained. The coating showed low wear rates against different friction pairs and presented excellent abrasive wear resistance at high applied load and the wear rates decreased with increasing loads, which exhibited an outstanding application prospect in cold working tool steels.

Fatigue life estimation of clinched joints from wrought aluminium alloy with Local Strain Approach considering cold working of joining process

Mechanical clinching is an ef- ficient join- ing tech- nique fre- quently used in the au- tomotive industry to join sub- assemblies of the car body. Dur- ing me- chanical clinching, the ma- terial in the joint is cold worked altering the cyclic material proper- ties and affecting the per- formance of the joint under cyclic loading. The pa- per presents an approach for fatigue life es- timation of clinched joints us- ing the Local Strain Approach. Numer- ical sim- ulation is utilized to retrieve local stresses and strains in the crit- ical re- gion. Ex- perimen- tal inves- tigation is presented to vali- date the crack ini- tiation lo- cation and an assess- ment of the fa- tigue life estima- tion is car- ried out.

Manufacturing of Tool Steels by PBF-EB

Additive manufacturing (AM) of metals is stimulating the tool making industry. Moreover, besides the production of lost forms, AM processes are now being used to directly generate tools, molds or parts, leading to massive time savings. In the case of material development for AM, the challenge is to operate with carbon-containing iron-based materials distinguished by high strength and hardness, as well as high corrosion resistance and thermal conductivity. Often, those materials are susceptible to crack formation during processing. Using Electron Beam Powder Bed Fusion (PBF-EB), the challenge of crack formation can be overcome by using high process temperatures in the range 800–900 °C. In this paper, results on the processing of a cold-working tool steel (X65MoCrWV3-2) and a hot-working steel (X37CrMoV5-1) will be presented. These include the processing window, processing strategies to minimize the density of cracks and properties with respect to microstructure and hardness.

The Same Drift Monodiameter Completion System in Solving Drilling and Well Infrastructure Challenges

The public domain contains many work efforts that document the advantages of expandable drilling and completions systems within the industry (Filippov 1999, Lohoefer 2000). The ability to place a solid steel liner or patch into a well and transform it by cold working to a larger diameter provides an opportunity to drill deeper while maintaining sufficient wellbore diameter. The use of expandable technology has led to the development of a formable and retractable-segmented cone. The cone supports an expandable system capable of passing through the drift of a base casing that can then result in an expansion providing the equivalent drift diameter. The technology allows the placement of additional liner points in a well that can extend liner lengths as well as isolate sections of open hole that were previously impossible to isolate due to wellbore geometry restriction. There are no limitations on the number of open hole patches installed in a given well which are helpful when wells experience multiple drilling hazards. Each patch can pass through a previously installed patch. The idea of monodiameter expandable liners began in the early 2000s (Dupal 2002, Dean 2003). This paper presents the technical challenges, solutions, and testing of a novel monodiameter system that expands 11-3/4 in. 47 lb/ft pipe which can result in a post-expansion drift diameter of 12-1/4 in. Finite element analysis helped transform the concept from the theoretical system to field execution. The work efforts show the successful testing of the monobore system at surface, and the resulting field trials demonstrate the ability of the technology to fulfil the installation objectives. In addition, the success of the methodology has led to the development of additional monobore system sizes.

Problems Associated with Heat Treated Parts

This article introduces some of the general sources of heat treating problems with particular emphasis on problems caused by the actual heat treating process and the significant thermal and transformation stresses within a heat treated part. It addresses the design and material factors that cause a part to fail during heat treatment. The article discusses the problems associated with heating and furnaces, quenching media, quenching stresses, hardenability, tempering, carburizing, carbonitriding, and nitriding as well as potential stainless steel problems and problems associated with nonferrous heat treatments. The processes involved in cold working of certain ferrous and nonferrous alloys are also covered.

Failures of Tools and Dies

This article discusses failure mechanisms in tool and die materials that are very important to nearly all manufacturing processes. It is primarily devoted to failures of tool steels used in cold working and hot working applications. The processes involved in the analysis of tool and die failures are also covered. In addition, the article focuses on a number of factors that are responsible for tool and die failures, including mechanical design, grade selection, steel quality, machining processes, heat treatment operation, and tool and die setup.