Evaluation of Solidification Cracking Susceptibility for Austenitic Stainless Steel during Laser Trans-Varestraint Test Using Two-dimensional Temperature Measurement

Abstract

Laser beam welding at high speeds enhances solidification cracking susceptibility, and brittleness temperature range must be measured under a high cooling rate to quantitatively evaluate the influence of welding speed upon the susceptibility. This work investigated the influence of welding speed upon the solidification cracking susceptibility of type 310S stainless steel using the laser Trans-Varestraint test. A multi-sensor camera based on two-color thermometry measured two-dimensional temperature distribution around the molten pool to obtain the temperature range along different solidification crack directions, and the applicability and accuracy of the two-dimensional temperature distribution technique for measuring temperature range of cracks was investigated. The brittleness temperature range was measured precisely with this method; it was nearly constant around 102°C at welding speeds from 0.2 to 2.0 m/min. The results demonstrated the effect of the welding speed from 0.2 to 2.0 m/min upon the solidification cracking susceptibility was very small.

Quantitative evaluation of augmented strain at the weld metal during the Trans-Varestraint test

“…Therefore, it is desirable to avoid hot cracking on the material surface when measuring the strain via in-situ observation during the Trans-Varestraint test. According to a previous study [7][8][9]13] on hot cracking, solidification cracking occurs between the solidification starting temperature and solidification completion temperature. In other words, solidification cracking is less likely to occur in the case of a small solidliquid coexistence temperature range.…”

“…The Varestraint test, proposed by Savage in 1965 [1], has been used for evaluating the susceptibility of weld hot cracking. Since then, many researchers have reported the evaluation result of weld hot cracking susceptibility using the Varestraint test [2][3][4][5][6][7][8][9]. Several approaches in the Varestraint test have been reported for evaluating the type of crack.…”

Relationship between Alloy Element and Weld Solidification Cracking Susceptibility of Austenitic Stainless Steel

“…This value is almost the same as the BTR in the type 310S stainless steel, which is generally used as fully austenitic stainless steel. 16) The BTR of 2Ti is 266.9°C, 2Nb is 150.1°C, and 2Zr is 194.1°C. The value of 2Ti is the highest and approximately three times that of 24Cr-26Ni.…”

Prediction of Residual Liquid Distribution of Austenitic Stainless Steel during Laser Beam Welding Using Multi-Phase Field Modeling

“…Figure 2(b) shows an image of the 2D temperature distribution along this target crack, which is expressed as a line. The temperature gradient along this crack is measured using only one 2D temperature distribution image, 1) as is shown in Fig. 2(c).…”