本计划旨在研究适用于九种海洋结构用低碳微合金钢可焊性的常规碳当量公式的有效性，包括确定CGHAZ硬度作为800°C至500°C冷却时间的函数，测量冷却时间/冷却速率作为焊接条件的函数，验证计算方法，通过三种不同的方法对热影响区微观结构和氢辅助开裂进行分类，即:Battelle下封头开裂，UT- 改进的氢敏感性和植入物开裂试验。测试的钢材为:HSLA-80-1、HSLA-80-2、HSLA-80M、HSLA-100、HSLA-130、HY-130、DQ-125、DQ-8O和AC-50。六种钢HSLA-80-1、HSLA-80-2、HSLA-80M、HSLA-100、HSLA-130和DQ-8O含有铜（>1 wt.%），并通过ε-铜沉淀得到强化。DQ-8O、DQ-125和AC-50的生产采用了现代热机械控制加工（TMCP），而海军HSLA钢则采用淬火和时效品种。该项目开始时进行的文献回顾揭示了TMCP和“新”钢的清洁度通过提供更多铁素体形核位置降低钢淬透性的效果。 因此，适用于常规钢的碳当量公式通常高估了TMCP钢的淬透性。

This program to investigate the validity of conventional carbon equivalent formulas applicable to the weldability of nine low-carbon micro-alloyed steels for marine structures included in its scope the determination of CGHAZ hardness as a function of cooling time from 800° to 500°C, measurement of cooling times/cooling rate as a function of welding conditions, validation of calculation methods, the categorization of HAZ microstructures and hydrogen assisted cracking by three different methods namely: the Battelle Underbead Cracking, UT-Modified Hydrogen Sensitivity and Implant Cracking tests. The steels tested were: HSLA-80-1, HSLA-80-2, HSLA-80M, HSLA-100, HSLA-130, HY-130, DQ-125, DQ-8O, and AC-50.Six steels, HSLA-80-1, HSLA-80-2, HSLA-80M, HSLA-100, HSLA-130, and DQ-8O, contain copper (>1 wt.%) and were strengthened by the precipitation of epsilon-copper. Modern thermomechanical controlled processing (TMCP) was employed in the production of DQ-8O, DQ-125 and AC-50, whereas the Navy HSLA steels were of quenched and aged variety. The literature review conducted at the inception of this program revealed the effects of TMCP and cleanliness of the "new" steels in reducing the hardenability of steels by providing more sites for ferrite nucleation. Therefore, the carbon equivalent formulas applicable to the conventional steels generally overestimate the hardenability of the TMCP steels.