We construct the thermokinetic diagrams of austenite decomposition and analyze the influence of the rate of cooling of specimens simulating the metal of the heat-affected zone (HAZ) on the structure and durability of Quardian-500 and Armstal-500 high-strength steels. The regularities of the influence of carbon on the structure formation in the HAZ metal are determined for these steels and the susceptibility to brittle fracture is estimated. It is shown that, in Quardian-500 steel with a carbon content of 0.26%, a predominantly martensitic structure with a hardness of 4850–4890 MPa is formed in the zone of overheating for cooling rates of 20–30°C/sec, whereas in Armstal-500 steel with a carbon content of 0.29%, the transformation of overcooled austenite in the HAZ of simulating specimens occurs at cooling rates of 7–30°C/sec and is accompanied by the formation of martensitic structure with a hardness of 5160–5390 MPa, which improves the static strength of the products.

中文翻译：

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高强装甲钢焊接接头热影响区金属的结构变化

我们构建了奥氏体分解的热动力学图，并分析了模拟热影响区 (HAZ) 金属试样的冷却速率对 Quadian-500 和 Armstal-500 高强度钢的结构和耐久性的影响。确定了这些钢的碳对 HAZ 金属结构形成的影响规律，并估计了脆性断裂的敏感性。结果表明，在含碳量为 0.26% 的 Quardian-500 钢中，在冷却速度为 20-30°C/sec 的过热区形成硬度为 4850-4890 MPa 的主要马氏体组织，而在含碳量为 0.29% 的 Armstal-500 钢中，