低合金高强钢大热输入焊接热影响区组织性能

Microstructure and properties of high heat input welding HAZ of high strengthen steel

利用MMS—200热力模拟试验机研究了610 MPa级低合金高强度钢不同热输入焊接热影响区粗晶区（coarse grain high affected zone,CGHAZ）的组织和性能.结果表明,随着热输入的增加,试验钢CGHAZ组织逐渐粗大,低温冲击吸收功下降,但在80~100 kJ/cm的大热输入冲击下,热影响区仍能够保持良好的低温韧性,只有在120 kJ/cm的大热输入下,韧性显著下降.钢中弥散分布着大量细小TiN粒子（在焊接热循环中抑制原奥氏体长大、作为形核点促进针状铁素体形成）,是保证钢板具有良好的抗大热输入焊接性能的主要原因.

The microstructure and mechanical properties of coarse grain heat-affected zone(CGHAZ) of 610 MPa high strengthen steel which were treated under series high weld heat input by MMS-200 thermal simulation machine were studied.The results show that the test steel has good ability to resist thermal shock of 80-100 kJ/cm welding heat input,even after 120 kJ/cm welding heat input,the low-temperature toughness of heat-affected zone still keeps high level.With the increasing of welding heat input,the microstructure of CGHAZ gradually becomes more coarse and the toughness gradually worse;there are many fine and dispersed second-phase particle of TiN in test steel,which can prevent growth of primitive austenite,promote phase transformation of ferrite as nucleus and make the steel to resist thermal shock of high welding heat input.