| Due to the high carbon equivalent, high-strength wear-resistant steel NM360 which is widely used on excavating machinery always tends to welding crack during the manufacturing process. Heat affected zone (HAZ) is the weakest part in the welding joint. Most problems existing in HAZ such as harden quenching, cold crack, local brittleness as well as reheat crack are all related to the structure transformation and its products in HAZ material. In the present work, the impact ductility of NM360's HAZ under different cooling rate has been studied by using physical simulation method. And the impact ductility evolution mechanism has also been investigated according to the continuous cooling transformation (CCT) diagram which is taken from simulation. Microstructure, hardness, tendency of hardenability and possibility of generating cold crack of NM360's HAZ also can be predicted by CCT diagram. This study can provide useful data and lay experimental foundation for the research of weldability as well as the HAZ performance for NM360 steel. |
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