The impact of excessively high dehydrogenation temperatures on welds
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The cylinder is made of 14Cr1MoR steel; the thickness of the steel plate is δ=20 mm. It features longitudinal welds, with preheating to 150°C before welding, and hydrogen removal heat treatment after welding. Flame heating is used for dehydrogenation, with the process requirement being 300°C for 1.5 hours. However, the flame intensity was too high; it quickly heated up the weld area and the 200 mm surrounding area to a red heat, with the temperature likely reaching around 700°C. It is unknown what impact this has on weld quality and the base material of the equipment.
The last edit to this post was made by mefanfine on 2015-8-9 at 22:45. Here are some of my simple thoughts: it might affect the brittleness of the material after tempering, as well as the coarse grain structure of the welds; if cladding is applied on the inner side, it could have an impact on the stainless steel layer. Additionally, it’s best to use a thermometer to measure the temperature accurately. Lol, on a side note, how high is the flame intensity? Usually, it’s easy for the flame to lack sufficient strength, but in your case…
After welding, the weld area should be post-heated to 200°C; a normal post-heating time of 16 hours is sufficient.
Won’t this ruin the heat treatment condition of the material? . .
This post was last edited by 15837357920 on 2015-8-11 14:46. If it reaches 700 degrees, the state of the material is compromised. It is generally believed that temperatures above 480 degrees have an impact on the properties of the material. However, stress-relief annealing immediately after welding is allowed as a substitute for hydrogen removal; check whether what you are doing can be considered stress-relief annealing. 700 degrees is already close to the A1 line; the tissue begins to change. It’s best to determine this temperature; if it’s higher than 730 and exceeds A1, it is likely not suitable. If it is below 700, it is considered a tempering or stress-relief annealing. It depends on whether your weld assessment supports it. It’s not easy to determine just like this.