Hardness Profiles of Quenched Steel Heat Affected Zones

Abstract

This paper reports the effects of chemical composition on the hardness of the heat affected zone of re-austenitized and water quenched steels. Heat affected zone peak temperatures in the range 300–1350 °C were simulated using a Gleeble 3800 simulator using thermal cycles appropriate to welds with cooling times between 800 and 500 °C of 12s. The maximum softening relative to the base material occurred in the intercritical and subcritical heat affected zones at the peak temperatures of 700 or 800 °C. Usually softening was greatest when the peak temperature was 700 °C. Linear regression analysis showed that carbon, and to some extent manganese and nickel, are detrimental at the peak temperature of 700 °C, but beneficial at the peak temperature of 800 °C in respect to softening relative to the base material, whereas niobium and especially molybdenum are beneficial at both temperatures. The beneficial effects of molybdenum alloying are seen down to peak temperatures of 400 °C whereas the effect of niobium microalloying is not statistically significant at peak temperatures lower than 700 °C. The softening in the intercritical, fine-grained and coarse grained heat affected zones are discussed and the effects of the alloying elements on the hardness of the subcritical heat affected zone are compared with their known effects on martensite hardness during conventional tempering.

Mechanical Properties in the Physically Simulated Heat-Affected Zones of 500 MPa Offshore Steel for Arctic Conditions

“…By adjusting the parameters, it is also possible to simulate relatively easily different heat inputs. In recent years physical simulation of HAZ has been used successfully in various studies [1][2][3][4]. Therefore, aim of the present study is to compare the mechanical properties, especially impact toughness, of different physically simulated HAZ to each others and to the base material that was not exposed to the heat input.…”

Low-temperature toughness properties of 500 MPa offshore steels and their simulated coarse-grained heat-affected zones

“…By adjusting the thermal cycle parameters, it is possible to simulate various types of welding methods with varying heat inputs and cooling rates. HAZ physical simulation has been used successfully in this way for many years [19][20][21][22].…”

HAZ Characterization of Automotive DP Steels by Physical Simulation

“…1a-b respectively. Due to the time-consuming procedure of determining and testing the HAZ of real welded samples, HAZ physical simulation provides an attractive alternative by enabling the reliable simulation, characterization and testing of different HAZ subzones [32,33,34]. The hardness and microstructure of the specimens were then tested and analysed using Vicker's hardness test and optical microscope respectively.…”