Structural Steels. Effect of Boron on Toughness of Quenched Steel with Various Carbon Contents.

Abstract

The effect of boron addition was investigated on the toughness of quenched steels whose carbon content extends from 0.2 to 0.8 percent. The results are as follows. (1) Impact values of boron added steels are higher than boron-free steels' over the above carbon range. (2) Boron increases effectively both crack initiation and propagation energies. (3) Typically in the case of 0.8% carbon, the dominant fracture mode is transgranular in the boron added steel, while it is intergranular in the boron-free. It suggests that the boron excludes phosphorous segregating at the grain boundaries and consequently it strengthens the grain boundaries.

Boron in Heat‐Treatable Steels: A Review

“…Through-hardening heat-treatable steels Enhance hardenability, thereby improve mechanical properties 0.0004-0.0070 [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Case-hardening steels Enhance hardenability, improve toughness 0.0010-0.0030 [23][24][25][26][27] Press-hardening steels Enhance hardenability so as to attain ultrahigh ultimate tensile strengths (UTS) 0.0020 [28] Wire rod steels Reduce strain aging due to nitrogen, thus reduce work hardening, improve ductility, formability, torsional ductility 0.0010-0.0060 [29][30][31][32] Cold-upsetting/cold-forging steels Improve toughness at low temperatures (À60 to À80 C) 0.0020-0.0040 [33][34][35] Ferritic stainless steel Improve surface quality of stainless strips 0.0005-0.0050 [36,37] Austenitic stainless steel Improve high-temperature strength 0.0100 [38,39] High strength interstitial-free steels Avoid secondary work embrittlement 0.0003-0.0040 [40][41][42][43][44] Creep-resistant steels Improve creep strength 0.0010-0.0140 [45][46]…”

Thermodynamic Analysis of the Fe–Nb–B Ternary System

“…Furthermore, the effect of B is to improve the impact properties of steels. 1) This is explained by the fact that B segregates at the grain boundary of steel before elements such as P do, which can degrade the impact value. In addition, B enhances the ductility of hot steel, and this is thought to be due to the precipitation of Fe 23 (B,C) 6 in the matrix.…”