Formation of Structure and Properties of 30HGSN2A Steel at Technological Stages of Manufacture of Heavy-Loaded Parts

2021 ◽  
Vol 316 ◽  
pp. 324-332
Author(s):  
V.S. Muratov ◽  
N.S. Yakimov

The cases of premature failure of the barrel of liquid damper, made of complex alloyed high-strength 30HGSN2A steel, are analyzed. The options failure and the causes of their occurrence are established. Fatigue failure of the barrels during an operation is due to the failure of the chrome coating of the rod and the appearance of scorings on the surface of the barrel. Cases of failure of the barrels during official tests are associated with the reduced hardenability and an increased tendency to decarburize steel in the bottom of the barrel, due to the increased nitrogen content here (due to segregation). The influence treatment conditions on the structure and properties of steel are investigated. Modes of dehydration and final heat treatment of the products to eliminate their premature failures are recommended. The proposed conditions, in particular, include increasing the dehydration temperature to 200-230 oС, reducing the exposure time at the hardening temperature and reducing the tempering temperature, using vacuum heating.

Author(s):  
V.S. Muratov ◽  
N.S. Yakimov

The causes of premature failure of liquid dampers made of high-strength steel 30KhGSN2A and used on vehicles are studied. Recommendations are developed on adjusting the modes of fi nishing heat treatment of barrels and surface treatment of rods, providing improved microstructure and the required level of steel properties, as well as reliable operation of the dampers.


2021 ◽  
Vol 410 ◽  
pp. 221-226
Author(s):  
Mikhail V. Maisuradze ◽  
Maxim A. Ryzhkov ◽  
Dmitriy I. Lebedev

The features of microstructure and mechanical properties of the aerospace high strength steel were studied after the implementation of various heat treatment modes: conventional oil quenching and tempering, quenching-partitioning, austempering. The dependence of the mechanical properties on the tempering temperature was determined. The basic patterns of the formation of mechanical properties during the implementation of isothermal heat treatment were considered. The optimal heat treatment conditions for the studied steel were established.


Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 647 ◽  
Author(s):  
Bingrong Zhang ◽  
Lingkun Zhang ◽  
Zhiming Wang ◽  
Anjiang Gao

In order to obtain high-strength and high-ductility Al–Si–Cu–Mg alloys, the present research is focused on optimizing the composition of soluble phases, the structure and morphology of insoluble phases, and artificial ageing processes. The results show that the best matches, 0.4 wt% Mg and 1.2 wt% Cu in the Al–9Si alloy, avoided the toxic effect of the blocky Al2Cu on the mechanical properties of the alloy. The addition of 0.6 wt% Zn modified the morphology of eutectic Si from coarse particles to fine fibrous particles and the texture of Fe-rich phases from acicular β-Fe to blocky π-Fe in the Al–9Si–1.2Cu–0.4Mg-based alloy. With the optimization of the heat treatment parameters, the spherical eutectic Si and the fully fused β-Fe dramatically improved the ultimate tensile strength and elongation to fracture. Compared with the Al–9Si–1.2Cu–0.4Mg-based alloy, the 0.6 wt% Zn modified alloy not only increased the ultimate tensile strength and elongation to fracture of peak ageing but also reduced the time of peak ageing. The following improved combination of higher tensile strength and higher elongation was achieved for 0.6 wt% Zn modified alloy by double-stage ageing: 100 °C × 3 h + 180 °C × 7 h, with mechanical properties of ultimate tensile strength (UTS) of ~371 MPa, yield strength (YS) of ~291 MPa, and elongation to fracture (E%) of ~5.6%.


2021 ◽  
Vol 410 ◽  
pp. 197-202
Author(s):  
Pavel P. Poleckov ◽  
Olga A. Nikitenko ◽  
Alla S. Kuznetsova

This study considers the influence of various heat treatment conditions on the change of steel microstructure parameters, mechanical properties and cold resistance at a temperature of-60 °C. The common behavior of these properties is considered depending on the heating temperature used for quenching and subsequent tempering. Based on the obtained results, heat treatment conditions are proposed that provide a combination of a guaranteed yield point σ0.2 ≥600 N/mm2 with a low-temperature impact toughness KCV-60 ≥50 J/cm2 and plasticity δ5 ≥17%. The obtained research results are intended for industrial use at the mill "5000" site of MMK PJSC.


2018 ◽  
Vol 284 ◽  
pp. 351-356 ◽  
Author(s):  
Mikhail V. Maisuradze ◽  
Maksim A. Ryzhkov

The high strength aerospace steel alloyed with Cr, Mn, Si, Ni, W and Mo was studied. The austenite transformations under continuous cooling conditions were investigated using the dilatometer analysis at the cooling rates 0.1...30 °C/s. The mechanical properties of the studied steel were determined after the conventional quenching and tempering heat treatment. The dependences of the mechanical properties on the tempering temperature were obtained. The novel quenching and partitioning heat treatment was applied to the steel under consideration. The microstructure and the mechanical properties were studied after three different modes of the quenching and partitioning (QP) treatment: single-stage QP, two-stage QP and single-stage QP with subsequent tempering (QPT).


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