摘要:
The present invention provides an abrasion resistant steel having a hardness of HB400 to HB520, having little change of hardness during long term use, and superior in toughness, characterized by containing, by mass %, C: 0.21% to 0.30%, Si: 0.30 to 1.00%, Mn: 0.32 to 0.70%, P: 0.02% or less, S: 0.01% or less, Cr: 0.1 to 2.0%, Mo: 0.1 to 1.0%, B: 0.0003 to 0.0030%, Al: 0.01 to 0.1%, and N: 0.01% or less, further containing one or more of V: 0.01 to 0.1%, Nb: 0.005 to 0.05%, Ti: 0.005 to 0.03%, Ca: 0.0005 to 0.05%, Mg: 0.0005 to 0.05%, and REM: 0.001 to 0.1%, having a balance of Fe, and furthermore having an ingredient with an M value defined by the following formula (1) of −10 to 16: M=26×[Si]−40×[Mn]−3×[Cr]+36×[Mo]+63×[V] (1)
摘要:
A propagation speed of a fatigue crack in a HAZ is restricted, and a fatigue strength of an as-welded joint can be improved, by limiting an area ratio of a ferrite micro-structure in the HAZ of the welded joint to 20 to 100% and the balance to one of a bainite, a martensite, a pearlite and a residual austenite micro-structure, or limiting a carbon equivalent of a steel plate used for the welded joint to not greater than 0.275.
摘要:
The present invention relates to a high tensile welded steel plate consisting essentially of, by weight, C: 0.03 to 0.20%, Si: 0.6 to 2.0%, Mn: 0.6 to 2.0%, Al: 0.01 to 0.08%, B: not more than 0.0020%, and N: 0.002 to 0.008% and optionally at least one element selected from Cu, Mo, Ni, Cr, Nb, V, Ti, Ca, and REM with the balance consisting of Fe and unavoidable impurities, and a process for producing a high tensile welded steel plate, usually comprising the steps of: subjecting a slab comprising the above chemical compositions to hot rolling or alternatively hot rolling followed by controlled rolling. The present invention enables fatigue cracking of the as-welded steel, in its heat-affected zone, to be prevented and, at the same time, the propagation of the crack to be prevented or inhibited.