With this article, the authors present a number of technological characteristics determined for a dual-phase steel with 0.09% C and 1.90% Mn. This steel was obtained through intercritical quenching: heating at 740, 780 and 820 °C, maintaining for 30 minutes and then cooling in water, oil, oil in magnetic field of direct current (DC) and oil in ultrasonic field. It was determined the degree of cold upsetting, the ultimate tensile strength of the resistance butt welded joints and the cutting property based on the study of cutting forces and surface roughness; it was analyzed the influence of heat treatment parameters (heating temperature, quenching medium) and ferrite-martensite structure on these characteristics.

In this article, the authors have analysed the influence of quenching temperature (TQ) on the mechanical properties of a dual-phase steel with 0.094 % C and 0.53% Mn. In order to obtain a ferrite-martensite structure, specimens of this material have been the subjected to intercritical quenching that consisted of heating at 750, 770, 790, 810 and 830 °C, maintaining for 30 minutes and cooling in water. These specimens have then been subjected to metallographic analysis and tensile test in order to determine the volume fraction of martensite (VM) in the structure, ultimate tensile strength (Rm), the 0.2% offset yield strength (Rp0.2), the total elongation (A5) and the Rp0.2/Rm ratio.

In this article, the authors present the cooling influence in ultrasonic field on the mechanical properties of a dual-phase steel with 0.09% C and 1.90% Mn obtained by intercritical quenching. The heat treatment consisted of heating to 740°C, maintaining for 30 minutes and then cooling in water and water in ultrasonic field. Mechanical properties have been highlighted through universal hardness testing; were determined: Martens hardness (HM), Martens hardness from the slope of the increasing force/indentation depth curve (HM S ), indentation hardness (H IT ), elastic indentation modulus (E IT ), indentation creep (C IT ), elastic (η IT ) and plastic (η plast ) parts of the

In this article, the authors have analysed the influence of quenching temperature (TQ) on the microstructure of a dual-phase steel with a low carbon and manganese content (0,094 % C and 0,53 % Mn). The ferrite-martensite structures, typical of the dual-phase steels, has been obtained by intercritical quenching that consisted of heating at temperatures (TQ) ranging between 750 °C and 830 °C, maintaining for 30 minutes and cooling in water. After carrying out intercritical heat treatments, samples have been subjected to metallographic analysis through which the volume fraction of martensite (VM), the volume fraction of ferrite (VF), the carbon content of the martensite (CM), the morphology and distribution of these phases have been determined, and then, the influence of quenching temperature (TQ) has been established.

This paper presents the influences of quenching technologies (classical, with cooling in magnetic field, cryogenic, with cooling in the ultrasonic field) on the dimensional stability in time and the contact fatigue behaviour of some elements of ball bearings made from 100Cr6 (RUL 1) steel. From the analysis of the experimental data obtained it has resulted that the use of ultrasound for martensitic quenching of these steels ensures changes to the properties favorable to elements of ball bearings and may represent an effective way of increasing the quality of bearings; the technology is relatively simple, it does not require substantial constructive changes in the quenching machines and no further investment of large values.