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A company produces truck wheel covers as spare parts for the local market. The production of these parts is based on a progressive die performing consecutive forming and selective cutting stages throughout the initial circular steel sheet. The failure occurred to the final stage of manufacturing, as the die marks, by mold-printing, the assembly configuration of the wheel cover onto the wheel rim. The paper presents a thorough failure analysis of the broken tool. The investigation includes preliminary examination, hardness measurements and chemical analysis. In depth microscopic examination was carried out using stereoscope and optical and electron microscopy. The failure mechanism was investigated from macroscopic and microscopic perspective and conclusions regarding the crack initiation and propagation were conducted and analyzed. The causes that led to the total fracture were discussed. The design of the tool and improper surface roughness are considered to be the main causes of the failure. Some complementary recommendations were proposed so to enhance the production rate of the specific tool.

The present study is focused on the failure of a die used in plastic injection moulding. The die was made from AISI H13 steel and was intended for the production of plastic cups used for the outer closure of cylindrical aluminium cans in coffee packaging. The appearance of the die provides a clear picture of degradations. Extended corrosion damage on various areas of the metallic part and a wide crack can be observed by the naked eye. Hardness measurements and chemical analysis eliminated the probability of faulty material selection or improper heat treatment. Visual inspection, macro-examination and microscopic observations of representative failed parts revealed that the failure was caused by corrosion that led to the total cracking of the die. The design deficiency and improper cooling conditions generated a complex fatigue-corrosion cracking mechanism that lead to the damage of the die after half of it’s predicted service life.

Tire recycling includes three steps: cutting strips, turning strips into small pieces, and shredding pieces into powder. The bases of the first stage machine’s cutting blades usually broke down provoking extensive down times. The paper is focused on the microscopic examination of the failed part. Historical data were collected, hardness measurements were carried out and chemical analysis was performed. The fracture surfaces and the cross section structure of the tool were in depth investigated by light and scanning electron microscopy. The fracture mechanism and the type of the fractures were discussed. The principal causes that led to the premature failure of the base are exposed. Considering the absence of similar failure analysis case studies in bibliography, the study may be useful for industries using similar cutting machinery.

The failure of a cutting tool intended for the production of car racks was investigated. The tool consisted of two parts, the mould and the counter-die. The die, made of AISI O1 steel and designed for cutting metal sheets up to 2 mm thick, failed during the final grinding process, before performing any production service. Recorded history was collected, with data concerning the material selection, the manufacturing conditions and the final heat treatment. The die was inspected visually and than photographed. Hardness measurements and chemical analysis were performed in order to identification the tool material. A representative sample was subjected to magnetic-particle inspection for the emergence of surface cracks. Specimens were examinated by optical and electron microscopy (SEM). The type of failure and the principal factors that caused it are studied, and some suggestions are presented, in order to avoid similar failures.

Nitriding is usually applied to alloyed steels with the scope of increasing their surface hardness and wear resistance. Warm working has been found to produce a fine-grained microstructure, which makes possible further treatment of low carbon steels. In combination with a low temperature thermochemical treatment, such as nitriding, warm working can be used to produce machine parts with a though core and with a hard, wear resistant surface layer. This paper presents a study of mechanical and structural properties of AISI 1015 carbon steel nitrided after warm rolling. The rolling was performed in the following conditions: temperature 670–550°C, rolling speed 1.39 s-1 and deformation ratio 36.4%. After rolling, the samples were reheated to 550°C for a duration varying from a few minutes to 10 hours. The microstructural changes were assessed by light microscopy and quantitative microscopy analysis. Warm rolled samples were ion nitrided at 510–520°C in dissociated ammonia. The microstructure was analyzed by scanning electron microscopy and the mechanical properties were evaluated by tensile testing, surface hardness and friction coefficient measurements. Prior application of warm rolling makes possible (in the sense that is a viable solution) the ion nitriding of low carbon steels in order to produce machine parts with improved mechanical properties in the core (due to warm rolling) and longer service life (due to ion nitriding).

This paper studies the fracture surfaces of an aluminium hot extrusion die that broke down during operation. The die was constructed, from H13 steel and was intended for the production of 60,000 Kg of aluminium profile. The male part fractured during operation after the production of 500 Kg profile. Initially, the machine and thermal treatments that were applied for construction of the die were collected and studied. The die was carefully inspected visually with a stereoscope. The fracture surfaces, some cracks, and the structure that was not affected by the failure, were investigated by optical microscopy. The thickness, quality and homogeneity of the nitrated layers were inspected. Additional information concerning the fracture was obtained by examining a primary crack using a scanning electron microscope and chemical analysis of the material was made using EDX attachment. The paper reports on some interesting observations relating to the fractured component, the type of the fractures, and the quality of the heat treatments, and presents some of the probable causes that led to the premature failure of the die.

Construction carbon steels represent an important steel class due to the large quantity in which it is produced. Generally, these steels are delivered in as‐rolled or normalized condition heaving a ferrite‐pearlite microstructure. For a given chemical composition, the mechanical characteristics of this microstructure are largely influenced by the grain size. Rolling is the deformation process which is most widely used for grain size refinement. Situated in the intermediate temperature range, warm‐rolling presents certain advantages as compared to classical hot‐ or cold‐working processes.The paper presents a study on the microstructure and mechanical properties of Ck15 carbon steel samples warm‐rolled. After deformation, the microstructure was investigated by light microscopy. Hardness measurements were made on the section parallel to the rolling direction. The mechanical properties of the steel after warm‐rolling were assessed by tensile and impact tests. Additional information concerning the fracture beh...