Maraging steel

About: Maraging steel is a research topic. Over the lifetime, 1728 publications have been published within this topic receiving 19886 citations. The topic is also known as: martensitic ageing steel.

The variant selection in the transformation from austenite to martensite in samples of maraging-350 steel

Abstract: Experiments have been conducted to study the variant selection phenomenon in the transformation from austenite to martensite in maraging-350 steel. The transformation of austenite to martensite in maraging steels occurs at temperatures below 300 °C depending on the alloy chemical composition. The transformation to martensite in these steels occurs regardless of the cooling rate. In these steels, the reverted austenite presents the same crystallographic texture of the mother austenite. Samples of maraging-350 were austenitized at 860 °C inside a furnace attached to a tension test machine and then cooled in the furnace until the temperature of 600 °C and 400 °C. At these temperatures samples were deformed by compression with 10% reduction in height. After deformation the applied force was removed and samples were cooled to room temperature in air. A second group of samples was subjected to the same austenitization and cooled until 300 °C when it was applied a compressive stress with magnitude below the yield strength. With the force applied, the samples were air cooled to room temperature. EBSD analysis was performed in cross-section of samples to determine the influence of plastic deformation before the transformation and also the influence of a stress in the elastic regime in the selection of variants of martensite. Measured pole figures were compared with calculated ones using the phenomenological martensite transformation concept associated with Patel–Cohen model.

Effect of conventional and subzero treating on the mechanical properties of aged martensitic Fe–12 wt.% Ni–X wt.% Mn alloys

Abstract: Fe–Ni–Mn maraging alloys are suffering from sever embrittlement after aging Mechanism of the embrittelement has not been well understood yet Segregation of Mn atoms or formation of Austenite particles at prior Austenite grain boundaries (PAGBs) have been reported as embrittelement mechanisms while it remains controversial now For better understanding of embrittelement behavior, effect of subzero treating after aging, double aging and modification of alloy composition on the mechanical properties and fracture behavior were investigated Alloys of chemical compositions Fe–119 wt% Ni–63 wt% Mn and Fe–105 wt% Ni–58 wt% Mo–3 wt% Mn were studied Double solution annealing was performed at 1223 and 1093 K for 36 ks followed by water quenching After aging at 723 K for 09 ks (under aging) and 1728 ks (over aging), tensile properties of specimens heat treated conventionally and cryogenically were measured Double aging was done at 623 K for 36 ks followed by a step aging at 753, 783 and 803 K Aging behavior and tensile properties of Fe–105 wt% Ni–58 wt% Mo–3 wt% Mn were investigated after aging at 773 K Results showed that alloy modification yields reasonable tensile properties while subzero treatment and double aging couldn’t improve tensile properties An insight toward more investigation of the embrittelement mechanism was made on the basis of this study

Assisted crack growth in maraging steel welds by gaseous hydrogen

Abstract: — The effects of environmental hydrogen content on fatigue crack growth rates (FCGRs) in T-250 maraging steel plates and laser welds were investigated. The influence of ageing treatments on fatigue characteristics of the alloy was also studied. Experimental results revealed that the accelerated FCGRs in the presence of hydrogen were always associated with changes in fracture modes that appear in compact-tension specimens. Even for overaged specimens with excellent resistance to gaseous hydrogen embrittlement, such an acceleration of crack growth in hydrogen could not be avoided. The crack path of underaged specimens in hydrogen was found mainly along prior austenite boundaries for steel plates and along coarse columnar boundaries for welds. In gaseous hydrogen, peak-aged welds exhibited intergranular and quasi-cleavage mixed fracture modes, compared to mainly quasi-clevage for similar aged steel plates. Hence, the enhancement of crack growth in hydrogen was more pronounced for the welds. Overaged welds showed higher FCGRs than the same aged steel plates only in hydrogen and for ΔK values greater than 20MPa√m.

Role of Chromium on Mechanical Properties of Fe - Mn - Ni - Mo - Ti Maraging Steels

Abstract: This experiment investigated the role of chromium in the mechanical properties of Fe-5Mn-9Ni-5Mo-1.5Ti maraging steels containing up to 3% chromium. Remarkable age-hardening responses were observed in the Fe-5Mn-9Ni-5Mo-1.5Ti and Cr-bcaring alloys. A ductile-brittle-ductile transition occurred in the Cr-bearing alloys during isothermal aging below 510°C. This was due to the segregation of titanium and manganese to prior austenite grain boundaries and their subsequent desegregation into the matrix. The addition of chromium to the base alloy considerably improved its ductility after aging at 520°C. From microstructure and AES analyses, it is suggested that chromium addition augments the volume fractions of (Fe,Mn)2Mo and η-Ni3Ti precipitates in the Fe-5Mn-9Ni-5Mo-Cr alloys, which act as sinks of manganese and titanium in the matrices. This resulted in the reduction of the alloying elements concentration in the matrix, which is followed by the reduction in the segregation level of the elements at prior austenite grain boundaries, and consequently enhanced intergranular fracture strength. The optimum combination of strength and ductility was obtained in the Fe-5Mn-9Ni-5Mo-3Cr-l.5Ti alloy aged at 520°C for 2 hr. and was σ0 2=1721 MPa, σLS=1756 MPa. and e,= 10.2%.

Transformation of reverted austenite in a maraging steel under external loading: an in-situ X-ray diffraction study using high-energy synchrotron radiation

Abstract: Reverted austenite strongly influences the mechanical properties of maraging steels. Therefore, X-ray diffraction using high-energy synchrotron radiation was applied for in-situ studying of the reverse martensitic phase transformation under external load in a PH 13-8 Mo maraging steel. The volume fraction of austenite, the domain size of the crystallites, and the lattice parameters were determined as function of strain for differently aged samples. It is shown that the reverted austenite is not mechanically stable under external load. Scanning of the fractured sample along the axial direction shows that the volume fraction of the austenite and the domain sizes strongly depend on the distance from the point of fracture initiation.