A New Alloying Concept for Low-Density Steels

Abstract

This paper introduces a new alloying concept for low-density steels. Based on model calculations, samples—or “heats”—with 0.7 wt% C, 1.45 wt% Si, 2 wt% Cr, 0.5 wt% Ni, and an aluminium content varying from 5 to 7 wt% are prepared. The alloys are designed to obtain steel with reduced density and increased corrosion resistance suitable for products subjected to high dynamic stress during operation. Their density is in the range from 7.2 g cm−3 to 6.96 g cm−3. Basic thermophysical measurements are carried out on all the heats to determine the critical points of each phase transformation in the solid state, supported by metallographic analysis on SEM and LM or the EDS analysis of each phase. It is observed that even at very high austenitisation temperatures of 1100 °C, it is not possible to change the two-phase structure of ferrite and austenite. A substantial part of the austenite is transformed into martensite during cooling at 50 °C s−1. The carbide kappa phase is segregated at lower cooling rates (around 2.5 °C s−1).

Influence of processing parameters of medium manganese steel with 5 % Mn on development of mechanical properties

“…For the experimental program, high-strength medium manganese steel with a carbon content of 0.2%, manganese 5% and aluminium 3 wt% was chosen (Table 1). Manganese as an austenite stabilizing element significantly reduces the fraction of ferrite because it shifts the transformation of austenite to ferrite in the CCT diagram to the right [1,7,9]. Manganese also causes together with silicon strengthening of the solid solution and retard carbide precipitation [2,10].…”

Effect of Refined Spheroidizated Structure on Mechanical Properties of Spring Steel 51CrV4

“…To accomplish this, they may seek new and alternative materials, e.g. springs with possible weight reduction [1] or quenched spring steel with the contribution of Cu precipitation hardening [2]. But also optimize or even completely change the manufacturing technology [3][4][5].…”

Mechanical Properties of High Carbon Low-Density Steels

“…However, the stability of ferrite is undesirable for the future modification of mechanical properties by heat treatment. It is, therefore, necessary to compensate for the high alumina content with austenite-forming elements, such as Mn and C. In this way, a fully austenitic structure can be achieved, at least, at higher temperatures, thus achieving suitable sub-conditions for heat treatment [ 3 , 15 ].…”

“…Our concept assumes the high thermal stability of the structure combined with heat treatment. Another benefit will be higher corrosion resistance, which is inherently typical for aluminium alloy steels [ 15 ].…”

“…In our paper, two types of steels are presented, which are based on the alloying concepts presented in [ 15 , 16 , 17 ] and modified so that their heat treatment can be carried out efficiently to achieve the required strength and deformation characteristics. The aim is to achieve a yield strength to ultimate strength ratio of max.…”