Post-Weld Heat Treatment

Problem 4 — HLHT: the double dividend of PWHT, and a thought-provoking twist (the A533B high-load-ratio finale)

The finale of the four problems on the A533B-1 welded plate: same temperature and regime as Problem 3 (HLAW) — −30 ℃, high load ratio — but with post-weld heat treatment (PWHT). This article works through HLHT to show the double dividend of PWHT — it both relaxes the residual field (K_I^S 46→5) and restores toughness by an order of magnitude (K_mat 62→321) — and how this drives K_r down from 3.94 to 0.60; plus a thought-provoking twist: even with smaller residuals and higher toughness, HLHT fails at a slightly lower load than HLAW.

Problem 2 — LLHT: PWHT Relaxes Residual Stress by an Order of Magnitude, Same Temperature and Region for a Head-to-Head

Second of four problems on the A533B-1 welded plate: same temperature as Problem 1 LLAW (−120 ℃), same region, same measured residual-stress profile — the only variable is that post-weld heat treatment (PWHT) was applied. Here we run LLHT in mechCalc's BS 7910 Clause 7 fracture-assessment calculator and watch a counter-intuitive result: its primary SIF is actually higher than LLAW, yet the assessment point lands lower, because the residual K_I^S drops from 46 to 5.

BS 7910 FAD Assessment: What Residual Stress Does, Seen Through a FITNET Case

A set of large welded A533B-1 steel plates tested in four-point bending to fracture, built to answer a question engineers keep asking: where exactly does welding residual stress push the assessment point on the Failure Assessment Diagram (FAD)? We first lay out the background and the shared method, then break the four specimens (LLAW / LLHT / HLAW / HLHT) into four problems, give the FAD inputs and results for each, and compare each result with the original literature, to see what residual stress and post-weld heat treatment each contribute.