White Phosphate Coatings Obtained on Steel from Modified Cold Phosphating Solutions

The article presents a method for obtaining white phosphate coatings on steel by cold method. The deposition of protective phosphate coatings was carried out from solutions based on the preparation “Majef”, consisting of manganese and iron phosphates. To obtain phosphate films of white color, it is proposed to introduce zinc and calcium nitrates into phosphating solutions at the rate of 25–30 g/L. The surface of phosphate coatings was studied using the SolverP47-PRO atomic force microscope images, and the average grain size was determined. The structural and phase composition of phosphate coatings was been studied using X-ray diffraction analysis. The protective properties of phosphate coatings were estimated by corrosion rate indicators calculated from corrosion diagrams. Fine-crystalline uniform coatings were obtained from modified phosphating solutions at room temperature on steel. The white color of phosphate coatings is due to the increased content of phosphophyllite, hopeite, and parascholzite in their structural and phase composition. By applying protective phosphate coatings of white color on a steel product, corrosion can be slowed down by 4–4.5 times. However, white phosphate coatings are inferior in protective properties to unpainted coatings. The index of change in the mass of samples with white phosphate coatings because of corrosion is 0.371–0.41 g/(m2·h), and with unpainted coatings is 0.128 g/(m2·h).

Study of hardness and morphology of carbide coatings obtained on complex shaped steel items by electro-spark alloying

The work investigated the possibility of forming carbide coatings by electrospark alloying on steel products of complex shape. It has been established that electrospark alloying at an AC current of 1.0 to 4.5 A makes it possible to form coatings of hard carbide alloy VK6 and T15K6 characterized by microhardness up to 11.5 GPa and by hardness HRA 86.6 and 81.5 with the nitial hardness of the steel product HRA 80.3.

Research of deformation compensation method in laser metal deposition process of 316L stainless steel product

It is exists the problem of big product manufacturing with minimal dimensions tolerances. To solve this problem it is necessary to compensate the deformations influence. In researching of method, it became clear that deformation degree has changed and depended on size and form of part. However, the amount of deformation degree to dimension of part is still independent of size. This fact has observed after production of axis-symmetrical parts. The simple axis-symmetrical part was built up. The dimensions of part was measured, and the compensation coefficient was calculated. The dimensions of part was scaled on this coefficient for compensation of shrinkage effect. After that the experiment was repeated.

Defects of the hardened layer at laser exposure

Purpose. It is necessary to investigate the influence of non-metallic inclusions on the formation of defects during laser processing. The aim of the work was to study the defects of the hardened layer of steels under laser action, associated with the presence of non-metallic inclusions. Methods. The materials for investigation were commercial steels containing different non-metallic inclusions. The specimens of different steels with preliminary polished surface were exposed to laser beaming on the installations GOS-30M and GUANTUM-16. The research methods were applied - petrography, X-ray microscopy (MS-46 Cameca) and optical microscopy (Neophot-21) to study defects and identify of inclusions. Results. It has been established that various types of defects appear on the surface and in the surface layer of steel under laser action, which are not connected and are associated with non-metallic inclusions. It is shown that non-metallic inclusions are the reason for the appearance of various kinds of defects in the hardened layer of steel products during laser processing (cracks, cavities, violation of the geometry of the hardened layer). The reasons for the appearance of defects associated with the presence of inclusions of various types are discussed. Scientific novelty. A classification of defects in the hardened layer is presented. The nature and features of the formation of defects, associated with the appearance of high-speed thermal stresses, structural inhomogeneity, as well as melting, thermal destruction and evaporation of inclusions emerging to the surface and located within the hardened layer, have been established. It is noted that the detected defects are ready-made centers of destruction of a steel product or part under conditions of static and dynamic loads, as well as contact stresses. Practical significance. It is shown that the unsatisfactory quality of the hardened layer associated with the presence of various kinds of defects near nonmetallic inclusions contributes to a decrease in the mechanical and operational characteristics of a steel product. The use of the obtained results will make it possible to develop technologies for laser processing of steels with regulated quality parameters of the hardened layer, which will prevent the formation of various kinds of defects. Keywords: steel; laser treatment; defects; cracks; hardened layer; non-metallic inclusions

ANALISIS PRODUKTIVITAS WAKTU BONGKAR STEEL PRODUCT ANTARA SHIP CRANE DAN GANTRY LIFTING CRANE (GLC) PADA MV. VTC PHOENIX (PT. DAISY MUTIARA SAMUDRA)

Laporan tugas akhir tersebut bertujuan untuk menganalisis produktivitas waktu bongkar steel product antara ship crane dan gantry lifting crane (GLC) pada mv. vtc phoenix (PT. Daisy Mutiara Samudra) yang lebih efektif diantara kedua alat tersebut. Sekaligus sebagai persyaratan kelulusan dari program studi Diploma III Transportasi Universitas Negeri Jakarta. Dalam penyusunan tugas laporan akhir ini dengan mengumpulkan data dalam bentuk primer dan sekunder. Data primer berupa wawancara serta observasi obyek ship crane dan gantry lifting crane. Data sekunder berupa data rekap manifest dan standar operasional prosedur. Waktu yang dibutuhkan untuk membongkar coils menggunakan GLC yaitu 8 jam 23 menit dan waktu yang dibutuhkan untuk membongkar coils menggunakan ship crane yaitu 10 jam. Dapat disimpulakan bahwa alat yang paling efektif dalam bongkar coils ialah GLC, karena mempunyai kapasitas angkut yang besar.

PENGARUH PROSES QUENCHING DENGAN MEDIA PENDINGIN AIR DAN OLI TERHADAP KEKERASAN BAJA DAN STRUKTUR MIKRO BAJA S45C

Perlakuan panas merupakan salah satu alternatif untuk meningkatkan kualitas suatu produk baja, pada saat mengoperasikan excavator di pertambangan tidak menutup kemungkinan komponen yang rusak atau aus harus segera diganti karena akan menghambat kinerja alat berat tersebut, tidak jarang akibatnya. untuk ketersediaan spare part original sedikit atau harus dipesan terlebih dahulu, untuk mengatasi lamanya waktu penggantian tentunya pihak perusahaan akan mencari komponen non original yang banyak beredar dipasaran tentunya dari segi kualitas atau waktu pemakaian. menjadi lebih pendek dari komponen aslinya. Untuk meningkatkan kualitas komponen tersebut maka dilakukan proses heat treatment (quenching) untuk meningkatkan kualitas komponen tersebut. Perlakuan panas dilakukan mulai dari memanaskan spesimen hingga suhu yang sesuai divariasikan (800 °C, 850 °C dan 900 °C) kemudian ditahan di dalam oven selama 2 jam dan kemudian didinginkan secara cepat menggunakan air dan minyak, jenis pendinginan ini akan berpengaruh kekerasan dan mikro. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh temperatur quenching dan jenis pendinginan terhadap kekerasan dan mikrostruktur. Heat treatment is an alternative to improve the quality of a steel product, when operating an excavator in mining does not rule out the possibility of damaged or worn components which must be replaced immediately because it will hamper the performance of the heavy equipment, not infrequently due to the availability of spare the original part is a little or must be ordered in advance, to overcome the lengthy replacement time of course the company will look for non-original components that are circulating in the market of course in terms of quality or usage time to be shorter than the original components. To improve the quality of these components, a heat treatment (quenching) process is carried out to improve the quality of the components. Heat treatment carried out starting from heating the specimens to the appropriate temperature varied (800 °C, 850 °C and 900 °C) then held in the oven for 2 hours and then cooled quickly using water and oil, this type of cooling will affect the hardness and microstructure. The purpose of this study was to determine the effect of quenching temperature and type of cooling on hardness and microstructure.