Effect of boron on the hardenability of high-purity alloys and commercial steels

Abstract

A st ud y was made of t he action of boron in relation to the hardenability of high-purity alloys varying in carbon content. The effectiveness of boron in enhancing the harden ability of t hese alloys and certain steels is believed to be due to its action in retarding the rate of nucleation of ferri te and carbide while in soli d solution in austenite. The hardenabi li ty of t he boron-treated a ll oys, as determined in terms of the cri tical coolin g rate of small specimens a usteniti zed at a ,vide range of temperatures, varied with t he prior history and with the carbon content. The hardenabili ty of a commer cial boron-treated steel, as determined by the end-quench test, was also sensitive to prior thermal t reatments. Boron was lost in t he decarburized zone of commercial steels, and i ts rate of diffusion apparently is of t he same order of magni tude as that of car bon. The heat t reatment of specim en s of t he alloys and tcel s to produce a boron const it uent and the microstructures of t h e alloys as cast and as h o mo~e ni ze d are described .

Boron in Heat‐Treatable Steels: A Review

“…Deboronization is an important aspect to be considered in boron‐alloyed steels, as using high temperatures during heat treatments can result in partial or complete loss of boron in the surface region . Boron loss from the surface into depths of up to 0.5 mm at temperatures above 900 °C for 2 h has been attributed to oxidation effects .…”

“…Boron loss from the surface into depths of up to 0.5 mm at temperatures above 900 °C for 2 h has been attributed to oxidation effects . Moreover, Digges et al reported about a loss of boron in the decarburized zone of steels, which can be explained by the fact that the diffusion rate is comparable to that of carbon.…”

“…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]…”

“…Deboronization is an important aspect to be considered in boronalloyed steels, as using high temperatures during heat treatments can result in partial or complete loss of boron in the surface region. [7,179] Boron loss from the surface into depths of up to 0.5 mm at temperatures above 900 C for 2 h has been attributed to oxidation effects. [117] Moreover, Digges et al [7] reported about a loss of boron in the decarburized zone of steels, which can be explained by the fact that the diffusion rate is comparable to that of carbon.…”

Produção e caracterização de barras laminadas do aço ao boro DIN 39MnCrB6-2

“…Aumento de 500 X. Ataque: Picral-4%. [29] . Figura 21 -Amostra de dimensões 12x12x55 mm de aço com baixo teor de carbono (AISI 4010), temperado e revenido (950°C-30min, têmpera em óleo + revenimentos 625°C-60min).…”