Influence of induction hardening parameters on the GS30Mn5 weld properties

This study examines parameters of post-weld heat treatment on the test specimens made of cast steel GS30Mn5. The welding is performed with shielded metal arc welding (SMAW) process. The aim is to obtain the surface without illicit cracks, with hardness ranging from 320 up to 400 HB. After induction heating, the specimens are cooled alternately with air and water. Decreased speed of quenching results in avoiding the occurrence of illicit splashes, while the hardness is maintained within the prescribed limits

The possibility of tribopair lifetime extending by welding of quenched and tempered stainless steel with quenched and tempered carbon steel

In the conditions of tribocorrosion wear, extending of parts lifetime could be achieved by using stainless steel,which is hardened to sufficiently high hardness. In the tribosystem bolt/ bushing shell/link plate of the bucket elevator transporter conveyor machine, the previously quenched and tempered martensitic stainless steel for bolts is hardened at ≈47 HRC and welded with the quenched and tempered high yield carbon steel for bolts. Additional material, based on Cr-Ni-Mo (18/8/6) is used. The microstructure and hardness of welded samples are tested. On the tensile tester, resistance of the welded joint is tested with a simulated experiment. Dimensional control of worn tribosystem elements was performed after six months of service

Quasiparticle spectra and excitons of organic molecules deposited on substrates: G0W0-BSE approach applied to benzene on graphene and metallic substrates

We present an alternative methodology for calculating the quasi-particle energy, energy loss, and optical spectra of a molecule deposited on graphene or a metallic substrate. To test the accuracy of the method it is first applied to the isolated benzene (C6H6) molecule. The quasiparticle energy levels and especially the energies of the benzene excitons (triplet, singlet, optically active and inactive) are in very good agreement with available experimental results. It is shown that the vicinity of the various substrates (pristine/doped graphene or (jellium) metal surface) reduces the quasiparticle HOMO-LUMO gap by an amount that slightly depends on the substrate type. This is consistent with the simple image theory predictions. It is even shown that the substrate does not change the energy of the excitons in the isolated molecule. We prove (in terms of simple image theory) that energies of the excitons are indeed influenced by two mechanisms which cancel each other. We demonstrate that the benzene singlet optically active (E1u) exciton couples to real electronic excitations in the substrate. This causes it substantial decay, such as {\Gamma} = 174 meV for pristine graphene and {\Gamma} = 362 meV for metal surfaces as the substrate. However, we find that doping graphene does not influence the E1u exciton decay rate.Comment: 16 pages, 14 figure

Influence of induction hardening parameters on the GS30Mn5 weld properties

This study examines parameters of post-weld heat treatment on the test specimens made of cast steel GS30Mn5. The welding is performed with shielded metal arc welding (SMAW) process. The aim is to obtain the surface without illicit cracks, with hardness ranging from 320 up to 400 HB. After induction heating, the specimens are cooled alternately with air and water. Decreased speed of quenching results in avoiding the occurrence of illicit splashes, while the hardness is maintained within the prescribed limits

Investigation of Causes of Scrap Occurrence in Thread Cutting on Steel Sleeves for Motorcar Industry

This paper studies causes of scrap occurrence, wear and breakage of cutters during thread cutting of steel sleeves poured in Al die castings of motor car engine components. It was concluded that the reason for occurrence of problems with thread cutting of sleeves most probably should be attributed to the fact whether hardness value reaches 200 HB or over 250 HB. The most probable reason for over wear and consequently to breakage of cutters and scrap occurrence, although castings display top quality, lies in the fact that the internal diameter of sleeves frequently falls down under minimally allowed tolerances for threaded sleeves

Istraživanje utjecaja pripreme površine osnovnog materijala na svojstva toplinski naštrcanog sloja

Using specimens, a research was conducted to determine the influence of the base material surface preparation for 42CrMo4 on the final coating, prior to actual thermal spraying. During thermal spraying, an Al-Ni-alloy was used as an interlayer before the actual coating with Cr-Mo-Ni. The surface hardness and the hardness distribution across the thickness of the sprayed coating were measured and the structure of respective sprayed coatings was photographed. A comparison of experimental results enabled the identification of the particular material preparation method with an optimal ratio of the satisfactory coating thickness and its hardness.Na uzorcima je istraživan utjecaj kvalitete pripreme površine osnovnog materijala 42CrMo4 prije naštrcavanja na svojstva toplinski plinski naštrcanog sloja. Pri naštrcavanju je kao međusloj korištena legura Al-Ni, dok je za završni sloj korištena legura Cr-Mo-Ni. Izvršena su ispitivanja površinske tvrdoće, toka tvrdoće po debljini naštrcanog sloja, te odgovarajuća snimanja struktura naštrcanih slojeva. Usporedbom rezultata ispitivanja utvrđena je priprema površine osnovnog materijala kod koje se postiže prihvatljiva debljina naštrcanog sloja uz postizanje zadovoljavajućih tvrdoća u naštrcanom sloju

Dependence of Al bronze surfaced layers on the postweld thermomechanical treatment

The research investigated properties of aluminum bronze welded to structural steel St 52-3 N. Surface material CuAl-A3 was welded in one and two layers. There were dimension, metallographic examination of structures and hardness measured before and after heat treatment and after pressurization of tested specimens. It was determined that the specimens achieved the best performance by welding two layers of surface material, by postweld heat treatment and by “hammering“

Tribocorrosion wear of austenitic and martensitic steels

This paper explores the impact of tribocorrosion wear caused by an aggressive acidic media. Tests were conducted on samples made of stainless steel AISI 316L, 304L and 440C. Austenitic steels were tested in their nitrided state and martensitic in quenched and tempered and then induction hardened state. Electrochemical corrosion resistance testing and analysis of the microstructure and hardness in the cross section was carried out on samples of selected steels. To test the possibility of applying surface modification of selected materials in conditions of use, tests were conducted on samples/parts in a worm press for final pressing

Istraživanje utjecaja pripreme površine osnovnog materijala na svojstva toplinski naštrcanog sloja

Using specimens, a research was conducted to determine the influence of the base material surface preparation for 42CrMo4 on the final coating, prior to actual thermal spraying. During thermal spraying, an Al-Ni-alloy was used as an interlayer before the actual coating with Cr-Mo-Ni. The surface hardness and the hardness distribution across the thickness of the sprayed coating were measured and the structure of respective sprayed coatings was photographed. A comparison of experimental results enabled the identification of the particular material preparation method with an optimal ratio of the satisfactory coating thickness and its hardness.Na uzorcima je istraživan utjecaj kvalitete pripreme površine osnovnog materijala 42CrMo4 prije naštrcavanja na svojstva toplinski plinski naštrcanog sloja. Pri naštrcavanju je kao međusloj korištena legura Al-Ni, dok je za završni sloj korištena legura Cr-Mo-Ni. Izvršena su ispitivanja površinske tvrdoće, toka tvrdoće po debljini naštrcanog sloja, te odgovarajuća snimanja struktura naštrcanih slojeva. Usporedbom rezultata ispitivanja utvrđena je priprema površine osnovnog materijala kod koje se postiže prihvatljiva debljina naštrcanog sloja uz postizanje zadovoljavajućih tvrdoća u naštrcanom sloju

Research into possibilities of reducing the X155CrVMo12-1 tool steel fragility

This research varies the parameters of austenitization and quenching of the tool steel X155CrVMo12-1. It also focuses on investigation of the structure, hardness and impact energy. It was determined that the cracks were generally intercrystalline, with carbide deposition. It was observed that quenching at the temperature interval from ≈ 700 °C to ≈ 600 °C, at a speed greater than 15 °C/s, achieved higher impact energy with about the same hardness. It was concluded that prevention of carbide coalescence had influence on the reduction of steel fragility