Effect of laser heat treatment on hole expansion performance of ultra-high strength steel
For two kinds of ultra-high strength steels,DP1180 and MS1500,the laser heat treatment was carried out for tensile specimens with different laser process parameters,and the mechanical properties of the laser heat treatment specimens were obtained by uniaxial ten-sile experiments based on digital image correlation(DIC)technology and microhardness tests,and the optimal laser heat treatment process parameters were determined.Laser heat treatment and hole expansion experiments were carried out for hole expansion specimens based on the optimal process parameters,and the effects of laser heat treatment on the hole expansion performance of the two kinds of ul-tra-high strength steels were studied.The results show that the hole expansion performance of the two kinds of ultra-high strength steels are improved,the hole expansion rate of DP1180 after laser heat treatment with laser power of 700 W and scanning speed of 5 mm·s-1 is in-creased by about 25.4%compared with that of the base material.The hole expansion rate of MS1500 after laser heat treatment with laser power of 625 W and scanning speed of 5 mm·s-1 is increased by about 34.4%compared with that of the base material.
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