船用低合金高强钢止裂温度相关性研究

为研究不同温度场条件下所测止裂温度的相关性，针对4种批号船用低合金高强钢，分别开展等温型双重拉伸试验和梯度温度型（以下简称“梯温型”）双重拉伸试验，测得了等温型止裂温度和梯温型止裂温度。结果表明，在同一主拉伸应力水平下，梯温型止裂温度值均高于等温型止裂温度值，两者差值与主拉伸应力近似呈线性增长关系、与板厚近似呈二次函数关系。从能量角度对等温型和梯温型双重拉伸试验过程进行分析，确定了影响等温型止裂温度和梯温型止裂温度相关性的主要因素为主拉伸应力、无塑性转变温度和板厚，同时初步给出了相关性表达式。4种批号钢板的试验结果表明，所建立的表达式能够较好地表征板厚不大于80 mm的船用低合金高强钢的等温型止裂温度和梯温型止裂温度的相关性。

Correlation Analysis on Crack Arrest Temperature of Low Alloy High Strength Hull Steels

Isothermal and temperature-gradient double tension tests have been conducted on 4 lots of low alloy high strength hull steels to study the correlation between crack arrest temperatures obtained in different temperature fields. Test results indicate that under the same main tensile stress, the value of temperature-gradient crack arrest temperature is higher than that of isothermal crack arrest temperature. The difference of these two temperatures increases linearly with the increase of main tensile stress and shows an approximately quadratic function relationship with the plate thickness. Test procedures of isothermal and temperature-gradient double tension tests have been analyzed from the perspective of energy balance and the main influencing factors including main tensile stress, nil-ductility transition temperature and plate thickness, on which basis, a correlation expression is proposed and its validity is identified by test data of low alloy high strength hull steels with thickness no more than 80 mm.