完全硬化区由细小针状马氏体、残余奥氏体和少量点状碳化物组成，过渡区由马氏体和回火索氏体（珠光体）组成；
The completely hardening region is composed of fine acicular martensites, residual austenites and a few dot-like carbonides and the transition region is made up of martensites and sorbites (pearlite).
结果表明，在连接杆焊缝附近的热影响区中存在大量针状马氏体组织，在低应力的作用下，导致材料发生脆性断裂。
The result shows that the fracture mode is low stress brittle fracture. The fracture is mainly caused by needle type martensite in the heat affected zone of the weld joint.
钢的组织主要由针状铁素体和马氏体两相组成。
Mainly its metallographic structure consists of acicular ferrite and martensite.
结果表明：试验钢的组织由细小岛状马氏体与针状铁素体为主构成，马氏体体积分数为27．6%。
The results showed that the microstructure of the steel was mainly composed of fine island-like martensite and acicular ferrite, with a 27.6% of martensite volume fraction.
其中针状铁素体之间细小的马氏体的存在与数量对钢的抗拉强度和低温冲击韧性起关键作用。
The existence and amount of small isolated martensite between the acicular ferrite play an important role in determining the tensile strength and low temperature impact toughness of the steels.
熔化区和固态相变区硬化相组织极为细小，马氏体呈微细针状，具有孪晶亚结构。
It is found that the structure of the hardened phase in melting and transformation zone is very tiny, the martensite appears to be tiny acicular and possesses twin substructure.
熔化区和固态相变区硬化相组织极为细小，马氏体呈微细针状，具有孪晶亚结构。
It is found that the structure of the hardened phase in melting and transformation zone is very tiny, the martensite appears to be tiny acicular and possesses twin substructure.
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