Weldability of High Tensile Manganese-Silicon Structural Steels

Summary

Abstract

A development research of weldable high tensile manganese silicon structural steels with tensile strengths of 52 to 60 kg/mm² and with a satisfactory notch toughness, were investigated by the 6th Reseach Committee of the Shipbuilding Research Association of Japan.
Test steels were of nine production heats with the silicon contents varied from 0.1 to 0.6 percents to determine its optimum range. Eithteen kinds of tests ; namely, notch sensitivity tests, bead-bend tests, cracking tests, heat-treatment tests, and etc., were used to evaluate the weldability of test steels, and the correlations among these tests were also studied.
From these studies, the composition limits and necessary properties to be adapted to weldable high tensile manganese silicon structural steels with thichnesses less than 20 mm were determined as follows ;
(a) Chemical composition (Ladle analysis) :
C ≤ 0.18% S ≤ 0.03%
Mn ≤ 1.25% Cu ≤ 0.30%
Si ≤ 0.55% Ni ≤ 0.25%
P ≤ 0.03% Cr ≤ 0.10%
(b) Mechanical properties :
Yield strength ≥ 32 kg/mm²
Tensile strength = 52 to 60 kg/mm²
Elongation (8″) ≥ 20 %
(c) Weldability tests :
i) V-Charpy test
Impact value (at 0°C) ≥ 3.5 kgm/cm²
ii) Austrian test (Kommerell type, longitudinal bead bend test) Max. bend angle ( ≤20°C) ≥120°, and Bend angle at first crack (≤20°C) ≥ 60°Note- Austrian test is only required for plate thichness, 18 to 20 mm, inclusive.