Experimental investigation of the formability of ultrahigh-strength sheet material using local heat treatment

Abstract

In this study, the effects of local heat treatment temperature on the V-bending formability of Martensitic 1200 steel, was investigated experimentally. In the first stage of the study, local heating temperatures were determined according to the stress-strain curves obtained as a result of the hot tensile test. Other experimental parameters included temperature (room temperature -RT/25, 300, 400 and 500°C), die-punch angle (30, 60, 90 and 120°) and punch holding time (0 and 10 s). The heating procedure in the bending operation was carried out locally only in the bending zone with the temperature controlled heating rod. The hardness values were found as 5.19% HV at the forming temperatures of RT-300°C, 2.31% HV at 300-400°C and 1.85% HV at 400-500°C. Due to the coarseness of the carbides in the microstructure, softening of the sheet material was observed up to 400°C. The slight increase in the flexure observed in the sheet materials bent at 500°C was caused by secondary precipitation hardening.

The effects of laser-assisted heat treatment on warm formability of dual-phase materials

“…It is known that the martensite ratios and hardness of DP steel materials, which contain martensite and ferrite phases in their microstructure, are reduced when they are heated compared to their room temperature conditions, in general [13,14]. Similar to this known situation, it was observed that the martensite ratios and hardness values of the DP800 samples decreased with the increase of the laser power used compared to the RT conditions.…”

“…It has been observed that the rate of ferrite in the material increases with the increase in temperature in locally applied heat treatments when various studies in the literature are examined. In this way, it has been observed that the amount of springback could be reduced and the formability feature could be increased [6][7][8][9][10][11][12][13][14][15][16][17][18]. During the forming of high-strength sheet metal materials at room temperature, dimensional forming errors which are called springback may also occur in addition to difficulties such as crack formation and breakage.…”

Experimental and numerical investigation of the springback behaviour of CP800 sheet after the V-bending process

“…Several researchers [16][17][18] have stated that the springback of sheet material is associated with tangential stresses. Looking again at the studies [19][20][21][22], an increase in holding time is shown to reduce the elastic return of the material, thus reducing the springback. In the present study, it was useful to consider the effect of holding time together with punch radius and die angle.…”

Experimental, Statistical, and Analytical Evaluation of The Springback Behavior of Martensitic 1400 Sheet in V-Bending

“…2). Only local heating was applied [18]. The warm forming process is often used to reduce springback in metal forming [19,20].…”