Effects of the Welding Heat Cycles on the Hardness and Microstructures of 308 Type Stainless Steel Weld Metal
1983 Volume 52 Issue 1 Pages 37-45
Details
1983 Volume 52 Issue 1 Pages 37-45
Changes of the metallurgical and mechanical properties, in the root pass weld metals accompanied with the repeated welding heat cycles of the multi-layer submerged arc welding, are studied. The obtained results are as follows.
1) The first and the second time welding heat cycle do not increase the hardness for the root pass weld-metal, and the hardnesses increase from Hv150 to Hv190 between the third and the sixth time welding heat cycle.
2) Cooling rates down to 500°C for the first time and the second welding heat cycle are 24°C/s and 5.9°C/s, cooling rate decreases till 1.5°C/s for the sixth welding heat cycle.
3) Precipitates are formed in the S ferrite along d ferrite-austenite boundaries, and the precipitates grow up to about 1000th in size.
4) Fine precipitates, which diameter are hundreds A, are formed in the austenite matrix, and the disloca-tions in the austenite matrix are fixed by these fine precipitates.
5) Dislocation densities in the austemte matrix are increased from 108/cm2 to 2×109/cm2 by the released strain accompanied with the six times repeated welding heat cycles.
