Study on Dynamic Mechanical Properties of Low-Alloy, High-Strength Steel Weld Metal at High Temperatures

TL;DR

This study examines how high temperatures affect the strength and durability of a specific type of steel weld metal, finding that heat treatments can significantly alter its mechanical properties.

Contribution

The paper introduces a steady-state temperature distribution model for weld metal and evaluates the effects of heat treatment on mechanical properties at high temperatures.

Findings

The weld seam is the weakest part of the welded joint, with strength decreasing as temperature increases.

Heat treatment at high temperatures significantly changes the weld tensile strength of Q960E steel.

Solid solution + aging treatment improves the mechanical properties of the heat-affected zone.

Abstract

To investigate the dynamic mechanical properties of low-alloy, high-strength steel weld metal at high temperatures, the temperature distribution equation and boundary conditions of weld metal during welding were determined. A steady-state temperature distribution model of weld metal heat loss was constructed by combining the heat loss equation and the heat source loss equation. Subsequently, a weld with Q960E high-strength steel extruded plate was used as the base material to investigate the dynamic mechanical properties of the weld metal at high temperatures. The experimental results show that the weld seam is the weakest region of the whole welded joint, and with the increase in temperature, the yield strength and tensile strength of the welded joints decrease. Heat treatment technology at high temperatures can significantly change the weld tensile strength of Q960E high-strength steel, and solid solution + aging treatment can optimize the mechanical properties of the heat-affected zone. We observed the short-term persistence of high-temperature metal at 600 °C/199 MPa and 650 °C/118 MPa; except for one 118 MPa short-term endurance test at high temperature, most samples qualified. With the increase in annealing temperature from 830 °C, the yield strength and tensile strength of the samples decreased significantly, and elongation after break increased dramatically.

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