A Microstructural and Damage Investigation into the Low Temperature Drop Weight Tear Test (DWTT) Behavior of an HSLA Steel

点击翻译按钮获取中文摘要

Stelco Canada is one of the top steel producers in North America, which operates the most modern greenfieldintegrated steel making facility on the continent. Recently re-established as an independent Canadiancompany, Stelco employs more than 2,200 personnel and produces a variety of steels for the automotive,energy and construction sectors.Recently, Stelco produced a hot rolled coil of a High Strength Low Alloy (HSLA) steel for a customer thatintended to use the material to construct vehicle impact barriers (guard rails). The material needed to meet ademanding Drop Weight Tear Test (DWTT) specification at low temperatures. The coil was produced using acoiling temperature of 550 degC, but did not meet the DWTT specification and resulted in a loss for Stelco. Asecond coil was produced using a coiling temperature to 500 degC, which met the DWTT specification, butwith mixed results. The effect of the coiling temperature on the (i) microstructure (ii) low temperature DWTTperformance and (iii) sporadic DWTT results for this grade of HSLA steel is not well understood, and formsthe basis of the proposed research. High resolution optical and field emission scanning electron microscopywill be used to quantify the effect of coiling temperature on the microstructure and damage evolution for theDWTT tested HSLA materials. The results will provide Stelco insight into the effect of coiling temperature onlow temperature DWTT performance of HSLA (and similar) steel grades and benefit the company by reducingcustomer coil rejections.Another problem faced by Stelco is associated with the DWTT test itself and how testing parameters (couponthickness, notch type, test energy and shear measurement) affect the results. A parametric DWTT study will beconducted at Stelco's R&D facility to better understand the test and standardize their testing procedure.