Abstract The mechanical properties of steels are strongly influenced by microstructure and texture developed during thermomechanical processing. Here, different annealing treatments have been performed on pipeline steel at inter-critical temperatures. The aim of this study is to relate hydrogen embrittlement behavior to the microstructural characteristics obtained through one-step, and two-step annealing treatments. Similar grain orientation distributions were observed after the initial hot rolling and the two-step annealing procedures. However, in the later process a dual-phase (i.e. ferrite-martensite) structure was formed; unlike in the starting material where only segregated patches of martensite were observed within a ferritic microstructure. The one-step treated steel was comprised of relatively large and primarily ferrite grains. As a result, the preliminary processing revealed the highest strength, with reduced ductility. The one-step treatment lowered strength and ductility. Although the two-step treated steel showed the lowest strength, it was the most ductile with improved resistance to hydrogen embrittlement. The tempering operation introduced in the two-step process created minimal strain and tempered martensite inside the steel. This reduced the tendency for hydrogen damage. A direct relationship was established between high tensile strength and increased embrittlement risks. Lowering the strength and hardness through double heat treatment cycles delayed the onset of cracking after pre-hydrogen charging.

中文翻译：

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后处理退火处理对API 5L X70管线钢组织发展和氢脆的影响

摘要 钢的力学性能受热机械加工过程中形成的显微​​组织和织构的影响很大。在这里，在临界温度下对管线钢进行了不同的退火处理。本研究的目的是将氢脆行为与通过一步和两步退火处理获得的微观结构特征联系起来。在初始热轧和两步退火程序后观察到类似的晶粒取向分布。然而，在后面的过程中形成了双相（即铁素体-马氏体）结构；不同于在起始材料中，在铁素体显微组织中仅观察到分离的马氏体斑块。一步处理的钢由相对较大的主要是铁素体晶粒组成。因此，初步加工显示出最高强度，但延展性降低。一步处理降低了强度和延展性。尽管经过两步处理的钢显示出最低的强度，但它的延展性最好，并且具有更高的抗氢脆性。在两步工艺中引入的回火操作在钢内部产生了最小的应变和回火马氏体。这降低了氢损伤的趋势。在高抗拉强度和增加的脆化风险之间建立了直接关系。通过两次热处理循环降低强度和硬度延迟了预充氢后开裂的发生。尽管经过两步处理的钢显示出最低的强度，但它的延展性最好，并且具有更高的抗氢脆性。在两步工艺中引入的回火操作在钢内部产生了最小的应变和回火马氏体。这降低了氢损伤的趋势。在高抗拉强度和增加的脆化风险之间建立了直接关系。通过两次热处理循环降低强度和硬度延迟了预充氢后开裂的发生。尽管经过两步处理的钢显示出最低的强度，但它的延展性最好，并且具有更高的抗氢脆性。在两步工艺中引入的回火操作在钢内部产生了最小的应变和回火马氏体。这降低了氢损伤的趋势。在高抗拉强度和增加的脆化风险之间建立了直接关系。通过两次热处理循环降低强度和硬度延迟了预充氢后开裂的发生。在高抗拉强度和增加的脆化风险之间建立了直接关系。通过两次热处理循环降低强度和硬度延迟了预充氢后开裂的发生。在高抗拉强度和增加的脆化风险之间建立了直接关系。通过两次热处理循环降低强度和硬度延迟了预充氢后开裂的发生。