Effect of heat treatment on the welded joint of X70 steel joined to duplex stainless steel by gas tungsten arc welding

Abstract

The objective of this work is to study the microstructure and the texture evolution in welded joint of X70 steel with duplex stainless steel joined by gas tungsten arc welding (GTAW) process and heat treated at 200 °C and 600 °C. Then, the microstructural evolutions are correlated to their hardness mechanical property. The characterization techniques used are optical microscopy, scanning electron microscopy, EDS, Vickers microhardness, tensile tests, X-ray diffraction, and electron backscatter diffraction (EBSD) technique. Two heat affected zones were observed in welded joint with different microstructures. Heat affected zone on the X70 steel side and another on the duplex stainless steel side. A solidification microstructure was observed in the fusion zone such elongated ferritic grains and a growth direction < 100 > was found. The most microstructural transformations were observed in the vicinity of the interface which connects the heat affected zone to the fusion zone either on the X70 steel side or on the duplex stainless steel side. The effect of heat treatment on the hardness of the welded joint was noticed in the side of the duplex stainless steel. The fusion zone is the hardest zone of the welded joint (309.4 Hv) and which is not affected by the applied heat. X-ray diffraction analysis did not reveal the formation of new phases after the heat treatments applied to the welded joint. The tensile tests have shown that the welded joint treated at 200 C presents the highest value of ultimate tensile strength (667 MPa).

Effects of Passivation with Cu and W on the Corrosion Properties of Super Duplex Stainless Steel PRE 42

“…XPS analysis revealed the factors influencing the passivation layer, and the results presented in Figure 11 and Table 5 reveal that the W 4+ reactant played a pivotal role [40]. In EN 1.4410, the passivation layer primarily comprises Cr 2+ , whereas that of EN 1.4501 is reinforced with a double layer attributed to W 4+ [13,19]. The relatively slower reactivity of W 4+ compared to the galvanic corrosion within the passivation layer enhanced its strengthening effect.…”

“…However, the high alloy content of SDSS makes controlling its microstructure and chemical composition challenging. Cu and W have demonstrated superior corrosion resistance compared with other austenitic stainless steels, and their effects on SDSSs are similar to those on austenitic stainless steels [12][13][14]. EN 1.4501 is prepared by adding Cu and W to EN 1.4410.…”

Study of Electroless Nickel Plating on Super Duplex Stainless Steel for Lithium-Ion Battery Cases: Electrochemical Behaviour and Effects of Plating Time

“…Conversely, N, with its smaller atomic size, acts as an interstitial element, enhancing the passive layer as a strengthening agent. PRE = 1 wt.% Cr + 3.3 wt.% Mo + 16 wt.% N (1) To precipitate secondary phases, while preventing the high-temperature cracking caused by phase transformation, solution heat treatment was conducted at 1100 • C [34,[47][48][49]. Table 1 (row (b)) lists the contents of the austenite and ferrite phases in SAF2507 after solution heat treatment.…”

Effect of Secondary Phase on Electroless Ni Plating Behaviour of Super Duplex Stainless Steel SAF2507 for Advanced Li-Ion Battery Case

“…However, no research has focused on Ni plating. L. trinh and O. Beziou have studied SAF2507 welding [ 3 , 45 ]. With the recent surge in SDSS demand, numerous studies are underway.…”