镍-铬-钼合金铸钢冲击值偏低原因分析

P&H28A镍-铬-钼合金铸钢件电铲杠杆在取样进行常温冲击试验时,最小冲击值仅为7 J。通过对冲击残样分别进行金相检验、化学检验、断口及能谱分析,找出了造成冲击值偏低的原因。结果表明:在热处理未消除的沿原始粗大晶界上形成的网状碳化物破坏了基体的连续性,严重地降低了钢的冲击韧性。其次,冲击试样V型口存在较大的显微空隙也对冲击值降低起到促进作用。

Reason Analysis for Rather Low Impact Value of Ni-Cr-Mo Alloy Steel Casting

Shovel lever,a kind of Ni-Cr-Mo alloy steel casting with material standard PH28A is performed impact test at ambinent temperature when sampling,and the minimum impact value is only 7 J.Residual samples of the impact test was performed metallographic examination,chemical testing,fracture and energy spectrum analysis to identify the reasons for the low impact value.The results showed that network carbide formed along with original coarse grain boundary without being eliminated in heat treatment processing destroyed the continuity of basal body,which seriously reduced the impact toughness of steel.Secondly,superior microscopic gaps existing V-notch of the impact sample also facilitated to impact value debasement.