Solidification behaviour and microstructure of welding transition zone using low-transformation-temperature welding consumables

Abstract

The solidification behaviour and microstructure of welding transition zone between lowtransformation-temperature deposited metals and high-strength low-alloy steels were investigated. It was found that the steep composition gradient provided driving forces for the diffusion of carbon from base metal to weld metal, leading to the hardened and softened regions near fusion boundary. In weld metal near fusion boundary, there were retained δ-ferrites when the base metal dilution rate below 35% and Cr eq /Ni eq value larger than 2.62. Compared with martensite, the mixed microstructures of martensite + δ-ferrite obtained less strain localisation, dislocation density and more percentages of large misorientation, which were more liable to resist microcrack initiation and propagation during deformation.

Microstructure and mechanical properties of stainless steel clad plate welding joints by different welding processes

“…The Cr eq and Ni eq of the weld metals are listed in Table 4. When Cr eq /Ni eq < 1.37, austenite is taken as the initial solidified phase corresponding to A mode; when 1.37 ≤ Cr eq /Ni eq ≤ 1.48, the room temperature microstructure is mainly composed of austenite + martensite + ferrite (AF mode); when 1.48 ≤ Cr eq /Ni eq ≤ 2, the room temperature microstructure contains austenite + ferrite, corresponding to FA mode; when Cr eq /Ni eq > 2, only ferrite exists at room temperature (F Mode) [24, 25]. The Cr eq /Ni eq values of SSWM and the TLWM are located in the two-phase region (austenite + ferrite), and the δ-ferrite content is approximately in the range from 5 to 12%.…”

Surface- and volume-based investigation on influences of different Varestraint testing parameters and chemical compositions on solidification cracking in LTT filler metals

“…In particular, the proof that compressive residual stresses are formed [3,4], the investigation of the mechanisms of stress formation [5,6], and the effect on the fatigue strength [7,8] have been the subject of many research projects. Recent publications also deal with extended topics such as microstructure and the associated mechanical properties [9][10][11][12][13], the behaviour during multilayer welding [14][15][16][17][18], and the application of LTT in beam welding [19].…”

A Numerical Approach to Analyze Detail Mechanical Characteristic at the Crack Tip of SCC in Dissimilar Metal Welded Joints

“…Nickel base alloys, such as alloy 152/52M, alloy 182/82, and alloy 309L/308L, have been widely used as weld metals to connect the pipe nozzle and safety end of the primary circuit of the nuclear pressure vessel [1][2][3][4][5]. However, several studies have demonstrated that the distribution of microstructure and material mechanical properties in the heat-affected zone (HAZ) and dilution zone (DZ) of the welded joint has become much complex during the welding progress [6][7][8][9][10][11]. Meanwhile, the complicated mechanical characteristic at the crack tip caused by the heterogeneous material properties is one of the main factors for stress corrosion cracking (SCC) of dissimilar metal welded joints (DMWJs) [12].…”